db.collection.update()

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Definition定义

db.collection.update(query, update, options)

mongo Shell Method方法

This page documents the mongo shell method, and does not refer to the MongoDB Node.js driver (or any other driver) method. 此页面记录了mongoShell方法，未提及MongoDB Node.js驱动程序（或任何其他驱动程序）方法。For corresponding MongoDB driver API, refer to your specific MongoDB driver documentation instead.有关相应的MongoDB驱动程序API，请参阅特定的MongoDB驱动程序文档。

Modifies an existing document or documents in a collection. 修改集合中的一个或多个现有文档。The method can modify specific fields of an existing document or documents or replace an existing document entirely, depending on the update parameter.该方法可以修改现有文档的特定字段，也可以完全替换现有文档，具体取决于更新参数。

By default, the db.collection.update() method updates a single document. 默认情况下，db.collection.update()方法更新单个文档。Include the option multi: true to update all documents that match the query criteria.包括选项multi:true以更新与查询条件匹配的所有文档。

Syntax语法

The db.collection.update() method has the following form:db.collection.update()方法具有以下形式：

db.collection.update(
   <query>,
   <update>,
   {
     upsert: <boolean>,
     multi: <boolean>,
     writeConcern: <document>,
     collation: <document>,
     arrayFilters: [ <filterdocument1>, ... ],
     hint:  <document|string>        // Available starting in MongoDB 4.2
   }
)

Parameters参数

The db.collection.update() method takes the following parameters:db.collection.update()方法采用以下参数：

Parameter参数Type类型Description描述
query document

The selection criteria for the update. 更新的选择标准。The same query selectors as in the find() method are available.可用与find()方法中相同的查询选择器。

When you execute an update() with upsert:true and the query matches no existing document, MongoDB will refuse to insert a new document if the query specifies conditions on the _id field using dot notation.当执行upsert:true的update()时，如果查询使用点表示法在_id字段上指定条件，则MongoDB将拒绝插入新文档。

update document or pipeline

The modifications to apply. 要应用的修改。Can be one of the following:可以是以下选项之一：

Update document更新文档

Contains only update operator expressions.仅包含更新运算符表达式。

Replacement document替换文档

Contains only <field1>: <value1> pairs.仅包含<field1>: <value1>对。

Aggregation pipeline聚合管道 (Starting in MongoDB 4.2从MongoDB 4.2开始)

Contains only the following aggregation stages:仅包含以下聚合阶段：

For details and examples, see Examples.有关详细信息和示例，请参阅示例。

upsert boolean

Optional. 可选。If set to true, creates a new document when no document matches the query criteria. 如果设置为true，则在没有文档与查询条件匹配时创建新文档。The default value is false, which does not insert a new document when no match is found.默认值为false，当未找到匹配项时，不会插入新文档。

multi boolean

Optional. 可选。If set to true, updates multiple documents that meet the query criteria. 如果设置为true，则更新满足query条件的多个文档。If set to false, updates one document. 如果设置为false，则更新一个文档。The default value is false. 默认值为false。For additional information, see Update Multiple Documents Examples.有关更多信息，请参阅更新多个文档示例。

writeConcern document

Optional. 可选。A document expressing the write concern. 表达写关注的文档。Omit to use the default write concern w: 1.忽略使用默认的写关注点w:1。

Do not explicitly set the write concern for the operation if run in a transaction. 如果在事务中运行，请不要显式设置操作的写入关注点。To use write concern with transactions, see Transactions and Write Concern.要将写关注点用于事务，请参阅事务和写关注点。

For an example using writeConcern, see Override Default Write Concern.有关使用writeConcern的示例，请参阅覆盖默认写入关注点。

collation document

Optional.可选。

Collation allows users to specify language-specific rules for string comparison, such as rules for lettercase and accent marks.排序规则允许用户为字符串比较指定特定于语言的规则，例如字母大小写和重音符号的规则。

For an example using collation, see Specify Collation.有关使用collation的示例，请参阅指定排序规则。

New in version 3.4.版本3.4中的新功能。

arrayFilters array

Optional. 可选。An array of filter documents that determine which array elements to modify for an update operation on an array field.筛选文档的数组，用于确定要为数组字段上的更新操作修改哪些数组元素。

In the update document, use the $[<identifier>] to define an identifier to update only those array elements that match the corresponding filter document in the arrayFilters.在更新文档中，使用$[<identifier>]定义一个标识符，以便仅更新与arrayFilters中相应的筛选文档匹配的那些数组元素。

Note

You cannot have an array filter document for an identifier if the identifier is not included in the update document.如果标识符未包含在更新文档中，则不能为标识符创建数组筛选器文档。

For examples, see Specify arrayFilters for Array Update Operations.有关示例，请参阅为数组更新操作指定阵列过滤器。

New in version 3.6.版本3.6中的新功能。

hint Document or string文档或字符串

Optional. 可选。A document or string that specifies the index to use to support the query predicate.指定用于支持查询谓词的索引的文档或字符串。

The option can take an index specification document or the index name string.该选项可以采用索引规范文档或索引名称字符串。

If you specify an index that does not exist, the operation errors.如果指定的索引不存在，则操作将出错。

For an example, see Specify hint for Update Operations.有关示例，请参阅指定更新操作提示。

New in version 4.2.版本4.2中的新功能。

Returns返回

The method returns a WriteResult document that contains the status of the operation.该方法返回包含操作状态的WriteResult文档。

Access Control访问控制

On deployments running with authorization, the user must have access that includes the following privileges:在使用authorization运行的部署上，用户必须具有包括以下权限的访问权限：

The built-in role readWrite provides the required privileges.提供所需的权限的内置角色readWrite。

Behavior行为

Sharded Collections分片集合

To use db.collection.update() with multi: false on a sharded collection, you must include an exact match on the _id field or target a single shard (such as by including the shard key).若要在分片集合中使用db.collection.update()配合multi:false，则必须在_id字段中包含完全匹配的内容，或将单个分片作为目标（例如通过包含分片键）。

When the db.collection.update() performs update operations (and not document replacement operations), db.collection.update() can target multiple shards.当db.collection.update()执行更新操作（而不是文档替换操作），db.collection.update()可以针对多个分片。

See also参阅

findAndModify()

Replace Document Operations on a Sharded Collection替换切分集合上的文档操作

Starting in MongoDB 4.2, replace document operations attempt to target a single shard, first by using the query filter. 从MongoDB 4.2开始，替换文档操作尝试以单个分片为目标，首先使用查询过滤器。If the operation cannot target a single shard by the query filter, it then attempts to target by the replacement document.如果操作无法通过查询筛选器以单个分片为目标，则它将尝试通过替换文档以单个分片为目标。

In earlier versions, the operation attempts to target using the replacement document.在早期版本中，该操作尝试使用替换文档作为目标。

upsert on a Sharded Collection分片集合上的upsert

For a db.collection.update() operation that includes upsert: true and is on a sharded collection, you must include the full shard key in the filter:对于包含upsert: true且位于分片集合上的db.collection.update()操作，必须在筛选器中包含完整的分片键：

  • For an update operation.用于更新操作。
  • For a replace document operation (starting in MongoDB 4.2).用于替换文档操作（从MongoDB 4.2开始）。

However, starting in version 4.4, documents in a sharded collection can be missing the shard key fields. 但是，从版本4.4开始，分片集合中的文档可能会缺少分片键字段。To target a document that is missing the shard key, you can use the null equality match in conjunction with another filter condition (such as on the _id field). 要将缺少shard键的文档作为目标，可以将null相等匹配与另一个筛选条件（例如在_id字段上）结合使用。For example:例如：

{ _id: <value>, <shardkeyfield>: null } // _id of the document missing shard key

Shard Key Modification分片密钥修改

Starting in MongoDB 4.2, you can update a document’s shard key value unless the shard key field is the immutable _id field. 从MongoDB 4.2开始，您可以更新文档的分片键值，除非分片键字段是不可变的_id字段。Before MongoDB 4.2, a document’s shard key field value is immutable.在MongoDB 4.2之前，文档的分片键字段值是不可变的。

To modify the existing shard key value with db.collection.update():要使用db.collection.update()修改现有切分键值，请执行以下操作：

  • You must run on a mongos. 您必须在mongos上运行。Do not issue the operation directly on the shard.不要直接在分片上发出操作。
  • You must run either in a transaction or as a retryable write.您必须在事务中运行，或作为可重试写入运行。
  • You must specify multi: false.必须指定multi:false。
  • You must include an equality query filter on the full shard key.必须在完整分片键上包含相等查询筛选器。

Tip

Since a missing key value is returned as part of a null equality match, to avoid updating a null-valued key, include additional query conditions (such as on the _id field) as appropriate.由于缺少的键值是作为空相等匹配的一部分返回的，为了避免更新空值键值，请酌情包括其他查询条件（例如在_id字段上）。

See also upsert on a Sharded Collection.另请参见在分片集合上upsert。

Missing Shard Key缺少分片键

Starting in version 4.4, documents in a sharded collection can be missing the shard key fields. 从4.4版开始，切分集合中的文档可能会缺少切分键字段。To use db.collection.update() to set the document’s missing shard key, you must run on a mongos. 使用db.collection.update()以设置文档缺少的碎片密钥，必须在mongos上运行。Do not issue the operation directly on the shard.不要直接在分片上发布操作。

In addition, the following requirements also apply:此外，以下要求也适用：

 Requirements要求
To set to null
  • Can specify multi: true.可以指定multi:true。
  • Requires equality filter on the full shard key if upsert:true.如果upsert:true，则需要对完整分片键进行相等筛选。
To set to a non-null value设置为非null值
  • Must be performed either inside a transaction or as a retryable write.必须在事务内部或作为可重试写入执行。
  • Must specify multi: false.必须指定multi:false。
  • Requires equality filter on the full shard key if either:如果出现以下情况之一，则需要对完整分片键进行相等筛选：
    • upsert: true, or，或者
    • if using a replacement document and the new shard key value belongs to a different shard.如果使用替换文档，则新的分片键值属于不同的分片。

Tip

Since a missing key value is returned as part of a null equality match, to avoid updating a null-valued key, include additional query conditions (such as on the _id field) as appropriate.由于缺少的键值是作为空相等匹配的一部分返回的，为了避免更新空值键值，请酌情包括其他查询条件（例如在_id字段上）。

See also:参阅：

Transactions事务

db.collection.update() can be used inside multi-document transactions.db.collection.update()可以在多文档事务中使用。

Important重要的

In most cases, multi-document transaction incurs a greater performance cost over single document writes, and the availability of multi-document transactions should not be a replacement for effective schema design. 在大多数情况下，与单文档写入相比，多文档事务会带来更大的性能成本，而多文档事务的可用性不应取代有效的模式设计。For many scenarios, the denormalized data model (embedded documents and arrays) will continue to be optimal for your data and use cases. 对于许多场景，非规范化数据模型（嵌入式文档和数组）将继续适合您的数据和用例。That is, for many scenarios, modeling your data appropriately will minimize the need for multi-document transactions.也就是说，对于许多场景，适当地建模数据将最大限度地减少对多文档事务的需求。

For additional transactions usage considerations (such as runtime limit and oplog size limit), see also Production Considerations.有关其他事务使用注意事项（如运行时限制和oplog大小限制），请参阅生产注意事项。

Upsert within Transactions在事务中插入

Starting in MongoDB 4.4 with feature compatibility version (fcv) "4.4", you can create collections and indexes inside a multi-document transaction if the transaction is not a cross-shard write transaction.从功能兼容版本（fcv）"4.4"的MongoDB 4.4开始，如果事务不是跨切分写入事务，则可以在多文档事务中创建集合和索引。

As such, for the feature compatibility version (fcv) is "4.4" or greater, db.collection.update() with upsert: true can be run against an existing collection or a non-existing collection. 因此，对于功能兼容性版本（fcv）为"4.4"或更高的版本，db.collection.update()配合upsert:true可以针对现有集合或不存在的集合运行。If run against a non-existing collection, the operation creates the collection.如果针对不存在的集合运行，该操作将创建该集合。

If the feature compatibility version (fcv) is "4.2" or less, the operation must be against an existing collection.如果功能兼容版本（fcv）为“4.2”或更低，则操作必须针对现有集合。

See also参阅

Create Collections and Indexes In a Transaction在事务中创建集合和索引

Write Concerns and Transactions撰写关注事项和交易记录

Do not explicitly set the write concern for the operation if run in a transaction. 如果在事务中运行，请不要显式设置操作的写入关注点。To use write concern with transactions, see Transactions and Write Concern.要将写关注点用于事务，请参阅事务和写关注点。

Examples示例

From the mongo shell, create a books collection which contains the following documents. 从mongo shell创建一个包含以下文档的books集合。This command first removes all previously existing documents from the books collection:此命令首先从books集合中删除所有以前存在的文档：

db.books.remove({});

db.books.insertMany([
  {
    "_id" : 1,
    "item" : "TBD",
    "stock" : 0,
    "info" : { "publisher" : "1111", "pages" : 430 },
    "tags" : [ "technology", "computer" ],
    "ratings" : [ { "by" : "ijk", "rating" : 4 }, { "by" : "lmn", "rating" : 5 } ],
    "reorder" : false
   },
   {
    "_id" : 2,
    "item" : "XYZ123",
    "stock" : 15,
    "info" : { "publisher" : "5555", "pages" : 150 },
    "tags" : [ ],
    "ratings" : [ { "by" : "xyz", "rating" : 5 } ],
    "reorder" : false
   }
]);

If the <update> document contains update operator modifiers, such as those using the $set modifier, then:如果<update>文档包含update运算符修饰符，例如使用$set修饰符的修饰符，则：

  • The <update> document must contain only update operator expressions.<update>文档必须仅包含更新运算符表达式。
  • The db.collection.update() method updates only the corresponding fields in the document.db.collection.update()方法只更新文档中相应的字段。
    • To update an embedded document or an array as a whole, specify the replacement value for the field.要整体更新嵌入的文档或数组，请指定字段的替换值。
    • To update particular fields in an embedded document or in an array, use dot notation to specify the field.要更新嵌入文档或数组中的特定字段，请使用点符号指定字段。

You can use the web shell below to insert the sample documents and execute the example update operation:您可以使用下面的web shell插入示例文档并执行示例更新操作：

db.books.update(
   { _id: 1 },
   {
     $inc: { stock: 5 },
     $set: {
       item: "ABC123",
       "info.publisher": "2222",
       tags: [ "software" ],
       "ratings.1": { by: "xyz", rating: 3 }
     }
   }
)

In this operation:在此操作中：

  • The <query> parameter of { _id: 1 } specifies which document to update,<query>参数{_id:1}指定要更新的文档，
  • the $inc operator increments the stock field, and$inc运算符增加stock字段，并且
  • the $set operator replaces the value of the$$set运算符替换
    • item field,领域
    • publisher field in the info embedded document,info嵌入文档中的publisher字段，
    • tags field, and字段，以及
    • second element in the ratings array.ratings数组中的第二个元素。

The updated document is the following:更新后的文件如下：

{
"_id" : 1,  "item" : "ABC123",
"stock" : 5,"info" : { "publisher" : "2222", "pages" : 430 },"tags" : [ "software" ],  "ratings" : [ { "by" : "ijk", "rating" : 4 }, { "by" : "xyz", "rating" : 3 } ],
  "reorder" : false
}

This operation corresponds to the following SQL statement:此操作对应于以下SQL语句：

UPDATE books
SET    stock = stock + 5
       item = "ABC123"
       publisher = 2222
       pages = 430
       tags = "software"
       rating_authors = "ijk,xyz"
       rating_values = "4,3"
WHERE  _id = 1

Note

If the query parameter had matched multiple documents, this operation would only update one matching document. 如果query参数匹配了多个文档，则此操作只会更新一个匹配的文档。To update multiple documents, you must set the multi option to true.要更新多个文档，必须将multi选项设置为true。

See also参阅

$set, $inc, Update Operators更新运算符, dot notation点符号

From the mongo shell, create a books collection which contains the following documents. 从mongo shell创建一个包含以下文档的books集合。This command first removes all previously existing documents from the books collection:此命令首先从books集合中删除所有以前存在的文档：

db.books.remove({});

db.books.insertMany([
  {
    "_id" : 1,
    "item" : "TBD",
    "stock" : 0,
    "info" : { "publisher" : "1111", "pages" : 430 },
    "tags" : [ "technology", "computer" ],
    "ratings" : [ { "by" : "ijk", "rating" : 4 }, { "by" : "lmn", "rating" : 5 } ],
    "reorder" : false
   },
   {
    "_id" : 2,
    "item" : "XYZ123",
    "stock" : 15,
    "info" : { "publisher" : "5555", "pages" : 150 },
    "tags" : [ ],
    "ratings" : [ { "by" : "xyz", "rating" : 5 } ],
    "reorder" : false
   }
]);

The following operation uses the $push update operator to append a new object to the ratings array.下面的操作使用$push更新运算符将一个新对象附加到ratings数组。

You can use the web shell below to insert the sample documents and execute the example update operation:您可以使用下面的web shell插入示例文档并执行示例更新操作：

db.books.update(
   { _id: 2 },
   {
     $push: { ratings: { "by" : "jkl", "rating" : 2 } }
   }
)

The updated document is the following:更新后的文件如下：

{
  "_id" : 2,
  "item" : "XYZ123",
  "stock" : 15,
  "info" : {
   "publisher" : "5555",
   "pages" : 150
  },
  "tags" : [ ],
  "ratings" : [
   { "by" : "xyz", "rating" : 5 },
{ "by" : "jkl", "rating" : 2 }  ],
  "reorder" : false
 }

See also参阅

$push

From the mongo shell, create a books collection which contains the following documents. 从mongo shell创建一个包含以下文档的books集合。This command first removes all previously existing documents from the books collection:此命令首先从books集合中删除所有以前存在的文档：

db.books.remove({});

db.books.insertMany([
  {
    "_id" : 1,
    "item" : "TBD",
    "stock" : 0,
    "info" : { "publisher" : "1111", "pages" : 430 },
    "tags" : [ "technology", "computer" ],
    "ratings" : [ { "by" : "ijk", "rating" : 4 }, { "by" : "lmn", "rating" : 5 } ],
    "reorder" : false
   },
   {
    "_id" : 2,
    "item" : "XYZ123",
    "stock" : 15,
    "info" : { "publisher" : "5555", "pages" : 150 },
    "tags" : [ ],
    "ratings" : [ { "by" : "xyz", "rating" : 5 } ],
    "reorder" : false
   }
]);

The following operation uses the $unset operator to remove the tags field from the document with { _id: 1 }.以下操作使用$unset运算符从带有{ _id: 1 }的文档中删除标记字段。

You can use the web shell below to insert the sample documents and execute the example update operation:您可以使用下面的web shell插入示例文档并执行示例更新操作：

db.books.update( { _id: 1 }, { $unset: { tags: 1 } } )

The updated document is the following:更新后的文件如下：

{
  "_id" : 1,
  "item" : "TBD",
  "stock" : 0,
  "info" : {
   "publisher" : "1111",
   "pages" : 430
  },
  "ratings" : [ { "by" : "ijk", "rating" : 4 }, { "by" : "lmn", "rating" : 5 } ],
  "reorder" : false
 }

There is not a direct SQL equivalent to $unset, however $unset is similar to the following SQL command which removes the tags field from the books table:没有与$unset等效的直接SQL，但是$unset类似于以下SQL命令，该命令从books表中删除tags字段：

ALTER TABLE books
DROP COLUMN tags

See also参阅

$unset, $rename, Update Operators更新运算符

From the mongo shell, create a books collection which contains the following documents. 从mongo shell创建一个包含以下文档的books集合。This command first removes all previously existing documents from the books collection:此命令首先从books集合中删除所有以前存在的文档：

db.books.remove({});

db.books.insertMany([
  {
    "_id" : 1,
    "item" : "TBD",
    "stock" : 0,
    "info" : { "publisher" : "1111", "pages" : 430 },
    "tags" : [ "technology", "computer" ],
    "ratings" : [ { "by" : "ijk", "rating" : 4 }, { "by" : "lmn", "rating" : 5 } ],
    "reorder" : false
   },
   {
    "_id" : 2,
    "item" : "XYZ123",
    "stock" : 15,
    "info" : { "publisher" : "5555", "pages" : 150 },
    "tags" : [ ],
    "ratings" : [ { "by" : "xyz", "rating" : 5 } ],
    "reorder" : false
   }
]);

If the <update> document contains only field:value expressions, then:如果<update>文档仅包含field:value表达式，则：

The following operation passes an <update> document that contains only field and value pairs. 以下操作将传递一个只包含字段和值对的<update>文档。The <update> document completely replaces the original document except for the _id field.除了_id字段外，<update>文档将完全替换原始文档。

You can use the web shell below to insert the sample documents and execute the example update operation:您可以使用下面的web shell插入示例文档并执行示例更新操作：

db.books.update(
   { _id: 2 },
   {
     item: "XYZ123",
     stock: 10,
     info: { publisher: "2255", pages: 150 },
     tags: [ "baking", "cooking" ]
   }
)

The updated document contains only the fields from the replacement document and the _id field. 更新后的文档仅包含替换文档和_id字段中的字段。As such, the fields ratings and reorder no longer exist in the updated document since the fields were not in the replacement document.因此，由于这些字段不在替换文档中，更新文档中不再存在rating和reorder字段。

{
   "_id" : 2,
   "item" : "XYZ123",
   "stock" : 10,
   "info" : { "publisher" : "2255", "pages" : 150 },
   "tags" : [ "baking", "cooking" ]
}

This operation corresponds to the following SQL statements:此操作对应于以下SQL语句：

DELETE from books WHERE _id = 2

INSERT INTO books
            (_id,
             item,
             stock,
             publisher,
             pages,
             tags)
VALUES     (2,
            "xyz123",
            10,
            "2255",
            150,
            "baking,cooking")

From the mongo shell, create a books collection which contains the following documents. 从mongo shell创建一个包含以下文档的books集合。This command first removes all previously existing documents from the books collection:此命令首先从books集合中删除所有以前存在的文档：

db.books.remove({});

db.books.insertMany([
  {
    "_id" : 1,
    "item" : "TBD",
    "stock" : 0,
    "info" : { "publisher" : "1111", "pages" : 430 },
    "tags" : [ "technology", "computer" ],
    "ratings" : [ { "by" : "ijk", "rating" : 4 }, { "by" : "lmn", "rating" : 5 } ],
    "reorder" : false
   },
   {
    "_id" : 2,
    "item" : "XYZ123",
    "stock" : 15,
    "info" : { "publisher" : "5555", "pages" : 150 },
    "tags" : [ ],
    "ratings" : [ { "by" : "xyz", "rating" : 5 } ],
    "reorder" : false
   }
]);

If multi is set to true, the db.collection.update() method updates all documents that meet the <query> criteria. 如果multi设置为true，则db.collection.update()方法更新满足<query>条件的所有文档。The multi update operation may interleave with other read/write operations.multi更新操作可能与其他读/写操作交织。

The following operation sets the reorder field to true for all documents where stock is less than or equal to 10. 以下操作将stock小于或等于10的所有文档的reorder字段设置为true。If the reorder field does not exist in the matching document(s), the $set operator adds the field with the specified value.如果匹配文档中不存在reorder字段，$set运算符将使用指定值添加该字段。

You can use the web shell below to insert the sample documents and execute the example update operation:您可以使用下面的web shell插入示例文档并执行示例更新操作：

db.books.update(
   { stock: { $lte: 10 } },
   { $set: { reorder: true } },
   { multi: true }
)

The resulting documents in the collection are the following:集合中产生的文档如下所示：

[
  {
    "_id" : 1,
    "item" : "ABC123",
    "stock" : 5,
    "info" : {
     "publisher" : "2222",
     "pages" : 430
    },
    "ratings" : [ { "by" : "ijk", "rating" : 4 }, { "by" : "xyz", "rating" : 3 } ],
"reorder" : true   }
   {
     "_id" : 2,
     "item" : "XYZ123",
     "stock" : 10,
     "info" : { "publisher" : "2255", "pages" : 150 },
     "tags" : [ "baking", "cooking" ],
"reorder" : true   }
]

This operation corresponds to the following SQL statement:此操作对应于以下SQL语句：

UPDATE books
SET reorder=true
WHERE stock <= 10

Note

You cannot specify multi: true when performing a replacement, i.e., when the <update> document contains only field:value expressions.在执行替换时，即<update>文档仅包含field:value表达式时，不能指定multi:true。

See also参阅

$set

Insert a New Document if No Match Exists如果不存在匹配项，就插入新文档 (Upsert)

When you specify the option upsert: true:指定选项upsert:true时：

If you specify upsert: true on a sharded collection, you must include the full shard key in the filter. 如果在分片集合上指定upsert:true，则必须在filter中包含完整的分片密钥。For additional db.collection.update() behavior on a sharded collection, see Sharded Collections.对于额外的db.collection.update()在分片集合上的行为，请参阅分片集合。

If no document matches the query criteria and the <update> parameter is a replacement document (i.e., contains only field and value pairs), the update inserts a new document with the fields and values of the replacement document.如果没有与查询条件匹配的文档，并且<update>参数是替换文档（即，仅包含字段和值对），则更新会插入一个包含替换文档的字段和值的新文档。

  • If you specify an _id field in either the query parameter or replacement document, MongoDB uses that _id field in the inserted document.如果在查询参数或替换文档中指定_id字段，MongoDB将在插入的文档中使用该_id字段。
  • If you do not specify an _id field in either the query parameter or replacement document, MongoDB generates adds the _id field with a randomly generated ObjectId value.如果在查询参数或替换文档中都没有指定_id字段，MongoDB会生成一个_id字段，并使用随机生成的ObjectId值添加该字段。

    Note

    You cannot specify different _id field values in the query parameter and replacement document. 不能在查询参数和替换文档中指定不同的_id字段值。If you do, the operation errors.如果这样做，操作就会出错。

For example, the following update sets the upsert option to true:例如，以下更新将upsert选项设置为true：

db.books.update(
   { item: "ZZZ135" },   // Query parameter
   {                     // Replacement document
     item: "ZZZ135",
     stock: 5,
     tags: [ "database" ]
   },
{ upsert: true }      // Options)

If no document matches the <query> parameter, the update operation inserts a document with only the replacement document. 如果没有与<query>参数匹配的文档，则更新操作将只插入替换文档。Because no _id field was specified in the replacement document or query document, the operation creates a new unique ObjectId for the new document’s _id field. 由于在替换文档或查询文档中未指定_id字段，因此该操作会为新文档的_id字段创建一个新的唯一的ObjectId。You can see the upsert reflected in the WriteResult of the operation:您可以在操作的WriteResult中看到upsert：

WriteResult({
  "nMatched" : 0,
  "nUpserted" : 1,
  "nModified" : 0,
  "_id" : ObjectId("5da78973835b2f1c75347a83")
 })

The operation inserts the following document into the books collection (your ObjectId value will differ):该操作将以下文档插入books集合（您的ObjectId值将不同）：

{
  "_id" : ObjectId("5da78973835b2f1c75347a83"),
  "item" : "ZZZ135",
  "stock" : 5,
  "tags" : [ "database" ]
}

If no document matches the query criteria and the <update> parameter is a document with update operator expressions, then the operation creates a base document from the equality clauses in the <query> parameter and applies the expressions from the <update> parameter.如果没有文档与查询条件匹配，并且<update>参数是具有更新运算符表达式的文档，则该操作将根据<query>参数中的等式子句创建一个基本文档，并应用<update>参数中的表达式。

Comparison operations from the <query> will not be included in the new document. 新文档中将不包括来自<query>的比较操作。If the new document does not include the _id field, MongoDB adds the _id field with an ObjectId value.如果新文档不包含_id字段，MongoDB会添加带有ObjectId值的_id字段。

For example, the following update sets the upsert option to true:例如，以下更新将upsert选项设置为true：

db.books.update(
   { item: "BLP921" },   // Query parameter
   {                     // Update document
      $set: { reorder: false },
      $setOnInsert: { stock: 10 }
   },
   { upsert: true }      // Options
)

If no documents match the query condition, the operation inserts the following document (your ObjectId value will differ):如果没有与查询条件匹配的文档，操作将插入以下文档（ObjectId值将不同）：

{
  "_id" : ObjectId("5da79019835b2f1c75348a0a"),
  "item" : "BLP921",
  "reorder" : false,
  "stock" : 10
}

See also参阅

$setOnInsert

If the <update> parameter is an aggregation pipeline, the update creates a base document from the equality clauses in the <query> parameter, and then applies the pipeline to the document to create the document to insert. 如果<update>参数是聚合管道，则更新将从<query>参数中的等式子句创建一个基本文档，然后将管道应用于文档，以创建要插入的文档。If the new document does not include the _id field, MongoDB adds the _id field with an ObjectId value.如果新文档不包含_id字段，MongoDB会添加带有ObjectId值的_id字段。

For example, the following upsert: true operation specifies an aggregation pipeline that uses例如，下面的upsert:true操作指定使用

  • the $replaceRoot stage which can provide somewhat similar behavior to a $setOnInsert update operator expression,$replaceRoot阶段可以提供与$setOnInsert更新运算符表达式类似的行为，
  • the $set stage which can provide similar behavior to the $set update operator expression,$set阶段可以提供与$set更新运算符表达式类似的行为，
  • the aggregation variable NOW, which resolves to the current datetime and can provide similar behavior to the $currentDate update operator expression.聚合变量NOW解析为当前日期时间，可以提供与$currentDate更新运算符表达式类似的行为。
db.books.update(
   { item: "MRQ014", ratings: [2, 5, 3] }, // Query parameter
   [                                       // Aggregation pipeline
      { $replaceRoot: { newRoot: { $mergeObjects: [ { stock: 0 }, "$$ROOT"  ] } } },
      { $set: { avgRating: { $avg: "$ratings" }, tags: [ "fiction", "murder" ], lastModified: "$$NOW" } }
   ],
   { upsert: true }   // Options
)

If no document matches the <query> parameter, the operation inserts the following document into the books collection (your ObjectId value will differ):如果没有与<query>参数匹配的文档，则操作会将以下文档插入books集合（ObjectId值将不同）：

{
   "_id" : ObjectId("5e2921e0b4c550aad59d1ba9"),
   "stock" : 0,
   "item" : "MRQ014",
   "ratings" : [ 2, 5, 3 ],
   "avgRating" : 3.3333333333333335,
   "tags" : [ "fiction", "murder" ],
   "lastModified" : ISODate("2020-01-23T04:32:32.951Z")
}

See also参阅

For additional examples of updates using aggregation pipelines, see Update with Aggregation Pipeline.有关使用聚合管道更新的其他示例，请参阅使用聚合管道更新。

Combine Upsert and Multi Options (Match)组合上插和多选项（匹配）

From the mongo shell, insert the following documents into a books collection:在mongo shell中，将以下文档插入books集合：

db.books.insertMany([
  {
    _id: 5,
    item: "RQM909",
    stock: 18,
    info: { publisher: "0000", pages: 170 },
    reorder: true
  },
  {
    _id: 6,
    item: "EFG222",
    stock: 15,
    info: { publisher: "1111", pages: 72 },
    reorder: true
  }
])

The following operation specifies both the multi option and the upsert option. 以下操作同时指定multi选项和upsert选项。If matching documents exist, the operation updates all matching documents. 如果存在匹配的文档，该操作将更新所有匹配的文档。If no matching documents exist, the operation inserts a new document.如果不存在匹配的文档，该操作将插入新文档。

db.books.update(
   { stock: { $gte: 10 } },        // Query parameter
   {                               // Update document
     $set: { reorder: false, tags: [ "literature", "translated" ] }
   },
   { upsert: true, multi: true }   // Options
)

The operation updates all matching documents and results in the following:该操作会更新所有匹配的文档，并产生以下结果：

{
   "_id" : 5,
   "item" : "RQM909",
   "stock" : 18,
   "info" : { "publisher" : "0000", "pages" : 170 },
   "reorder" : false,
   "tags" : [ "literature", "translated" ]
}
{
   "_id" : 6,
   "item" : "EFG222",
   "stock" : 15,
   "info" : { "publisher" : "1111", "pages" : 72 },
   "reorder" : false,
   "tags" : [ "literature", "translated" ]
}

Combine Upsert and Multi Options (No Match)组合向上插入和多个选项（不匹配）

If the collection had no matching document, the operation would result in the insertion of a single document using the fields from both the <query> and the <update> specifications. 如果集合中没有匹配的文档，则该操作将导致使用<query>和<update>规范中的字段插入单个文档。For example, consider the following operation:例如，考虑以下操作：

db.books.update(
  { "info.publisher": "Self-Published" },   // Query parameter
  {                                         // Update document
    $set: { reorder: false, tags: [ "literature", "hardcover" ], stock: 25 }
  },
  { upsert: true, multi: true }             // Options
)

The operation inserts the following document into the books collection (your ObjectId value will differ):该操作将以下文档插入books集合（您的ObjectId值将不同）：

{
  "_id" : ObjectId("5db337934f670d584b6ca8e0"),
  "info" : { "publisher" : "Self-Published" },
  "reorder" : false,
  "stock" : 25,
  "tags" : [ "literature", "hardcover" ]
}

When you execute an update() with upsert: true and the query matches no existing document, MongoDB will refuse to insert a new document if the query specifies conditions on the _id field using dot notation.当执行upsert:true的update()时，如果查询使用点表示法在_id字段中指定条件，则MongoDB将拒绝插入新文档。

This restriction ensures that the order of fields embedded in the _id document is well-defined and not bound to the order specified in the query.此限制可确保_id文档中嵌入的字段顺序定义良好，且不绑定到查询中指定的顺序。

If you attempt to insert a document in this way, MongoDB will raise an error. 如果试图以这种方式插入文档，MongoDB将引发错误。For example, consider the following update operation. 例如，考虑下面的更新操作。Since the update operation specifies upsert:true and the query specifies conditions on the _id field using dot notation, then the update will result in an error when constructing the document to insert.由于更新操作指定upsert:true，并且查询使用点表示法指定_id字段上的条件，因此在构造要插入的文档时，更新将导致错误。

db.collection.update( { "_id.name": "Robert Frost", "_id.uid": 0 },
   { "categories": ["poet", "playwright"] },
   { upsert: true } )

The WriteResult of the operation returns the following error:操作的WriteResult返回以下错误：

WriteResult({
  "nMatched" : 0,
  "nUpserted" : 0,
  "nModified" : 0,
  "writeError" : {
    "code" : 111,
    "errmsg" : "field at '_id' must be exactly specified, field at sub-path '_id.name'found"
  }
})

See also参阅

WriteResult()

Use Unique Indexes使用唯一索引

Warning

To avoid inserting the same document more than once, only use upsert: true if the query field is uniquely indexed.为了避免多次插入同一文档，仅当query字段被唯一索引时才使用upsert:true。

Given a collection named people where no documents have a name field that holds the value Andy, consider when multiple clients issue the following db.collection.update() with upsert: true at the same time:给定一个名为people的集合，其中没有文档具有值Andy的name字段，那么当多个客户端同时发出以下db.collection.update()配合upsert: true时：

db.people.update(
   { name: "Andy" },   // Query parameter
   {                   // Update document
      name: "Andy",
      rating: 1,
      score: 1
   },
   { upsert: true }    // Options
)

If all db.collection.update() operations complete the query portion before any client successfully inserts data, and there is no unique index on the name field, then each update operation may result in an insert.如果所有db.collection.update()操作在任何客户端成功插入数据之前完成query部分，并且name字段上没有唯一的索引，那么每个更新操作都可能导致插入。

To prevent MongoDB from inserting the same document more than once, create a unique index on the name field. 要防止MongoDB多次插入同一文档，请在name字段上创建唯一索引。With a unique index, if multiple applications issue the same update with upsert: true, exactly one db.collection.update() would successfully insert a new document.使用唯一索引，如果多个应用程序使用upsert:true发出相同的更新，则只有一个db.collection.update()将成功插入新文档。

The remaining operations would either:其余的行动将是：

  • update the newly inserted document, or更新新插入的文档，或
  • fail when they attempted to insert a duplicate.尝试插入副本时失败。

    If the operation fails because of a duplicate index key error, applications may retry the operation which will succeed as an update operation.如果操作因重复索引键错误而失败，应用程序可以重试该操作，该操作将作为更新操作成功。

See also参阅

$setOnInsert

Update with Aggregation Pipeline使用聚合管道更新

Starting in MongoDB 4.2, the db.collection.update() method can accept an aggregation pipeline [ <stage1>, <stage2>, ... ] that specifies the modifications to perform. 从MongoDB 4.2开始，db.collection.update()方法可以接受指定要执行的修改的聚合管道[ <stage1>, <stage2>, ... ]。The pipeline can consist of the following stages:管道可包括以下阶段：

Using the aggregation pipeline allows for a more expressive update statement, such as expressing conditional updates based on current field values or updating one field using the value of another field(s).使用聚合管道可以实现更具表现力的update语句，例如基于当前字段值表达条件更新，或者使用另一个字段的值更新一个字段。

Modify a Field Using the Values of the Other Fields in the Document使用文档中其他字段的值修改字段

Create a members collection with the following documents:使用以下文档创建members集合：

db.members.insertMany([
   { "_id" : 1, "member" : "abc123", "status" : "A", "points" : 2, "misc1" : "note to self: confirm status", "misc2" : "Need to activate", "lastUpdate" : ISODate("2019-01-01T00:00:00Z") },
   { "_id" : 2, "member" : "xyz123", "status" : "A", "points" : 60, "misc1" : "reminder: ping me at 100pts", "misc2" : "Some random comment", "lastUpdate" : ISODate("2019-01-01T00:00:00Z") }
])

Assume that instead of separate misc1 and misc2 fields, you want to gather these into a new comments field. 假设不需要单独的misc1和misc2字段，而是希望将它们收集到一个新的comments字段中。The following update operation uses an aggregation pipeline to:以下更新操作使用聚合管道来：

  • add the new comments field and set the lastUpdate field.添加新comments字段并设置lastUpdate字段。
  • remove the misc1 and misc2 fields for all documents in the collection.删除集合中所有文档的misc1和misc2字段。
db.members.update(
   { },
   [
      { $set: { status: "Modified", comments: [ "$misc1", "$misc2" ], lastUpdate: "$$NOW" } },
      { $unset: [ "misc1", "misc2" ] }
   ],
   { multi: true }
)

Note

The $set and $unset used in the pipeline refers to the aggregation stages $set and $unset respectively, and not the update operators $set and $unset.管道中使用的$set和$unset分别指的是聚合阶段$set和$unset，而不是更新运算符$set和$unset。

First Stage第一阶段

The $set stage:$set阶段：

  • creates a new array field comments whose elements are the current content of the misc1 and misc2 fields and创建一个新的数组字段comments，其元素是misc1和misc2字段的当前内容，以及
  • sets the field lastUpdate to the value of the aggregation variable NOW. 现在将字段lastUpdate设置为聚合变量NOW的值。The aggregation variable NOW resolves to the current datetime value and remains the same throughout the pipeline. 聚合变量NOW现在解析为当前日期时间值，并在整个管道中保持不变。To access aggregation variables, prefix the variable with double dollar signs $$ and enclose in quotes.要访问聚合变量，请在变量前面加上双美元符号$$并用引号括起来。
Second Stage第二阶段
The $unset stage removes the misc1 and misc2 fields.$unset阶段删除misc1和misc2字段。

After the command, the collection contains the following documents:命令发出后，集合包含以下文档：

{ "_id" : 1, "member" : "abc123", "status" : "Modified", "points" : 2, "lastUpdate" : ISODate("2020-01-23T05:11:45.784Z"), "comments" : [ "note to self: confirm status", "Need to activate" ] }
{ "_id" : 2, "member" : "xyz123", "status" : "Modified", "points" : 60, "lastUpdate" : ISODate("2020-01-23T05:11:45.784Z"), "comments" : [ "reminder: ping me at 100pts", "Some random comment" ] }

See also参阅

Updates with Aggregation Pipeline使用聚合管道进行更新

Perform Conditional Updates Based on Current Field Values基于当前字段值执行条件更新

Create a students3 collection with the following documents:使用以下文档创建students3集合：

db.students3.insert([
   { "_id" : 1, "tests" : [ 95, 92, 90 ], "lastUpdate" : ISODate("2019-01-01T00:00:00Z") },
   { "_id" : 2, "tests" : [ 94, 88, 90 ], "lastUpdate" : ISODate("2019-01-01T00:00:00Z") },
   { "_id" : 3, "tests" : [ 70, 75, 82 ], "lastUpdate" : ISODate("2019-01-01T00:00:00Z") }
]);

Using an aggregation pipeline, you can update the documents with the calculated grade average and letter grade.使用聚合管道，可以使用计算出的平均成绩和字母成绩更新文档。

db.students3.update(
   { },
   [
     { $set: { average : { $trunc: [ { $avg: "$tests" }, 0 ] }, lastUpdate: "$$NOW" } },
     { $set: { grade: { $switch: {
                           branches: [
                               { case: { $gte: [ "$average", 90 ] }, then: "A" },
                               { case: { $gte: [ "$average", 80 ] }, then: "B" },
                               { case: { $gte: [ "$average", 70 ] }, then: "C" },
                               { case: { $gte: [ "$average", 60 ] }, then: "D" }
                           ],
                           default: "F"
     } } } }
   ],
   { multi: true }
)

Note

The $set used in the pipeline refers to the aggregation stage $set, and not the update operators $set.管道中使用的$set指的是聚合阶段$set，而不是更新运算符$set。

First Stage第一阶段

The $set stage:$set阶段：

  • calculates a new field average based on the average of the tests field. 基于tests字段的平均值计算新字段average。See $avg for more information on the $avg aggregation operator and $trunc for more information on the $trunc truncate aggregation operator.有关$avg聚合运算符的更多信息，请参阅$avg；有关$trunc截断聚合运算符的更多信息，请参见$trunc。
  • sets the field lastUpdate to the value of the aggregation variable NOW. 现在将字段lastUpdate设置为聚合变量NOW的值。The aggregation variable NOW resolves to the current datetime value and remains the same throughout the pipeline. 聚合变量NOW现在解析为当前日期时间值，并在整个管道中保持不变。To access aggregation variables, prefix the variable with double dollar signs $$ and enclose in quotes.要访问聚合变量，请在变量前面加上双美元符号$$并用引号括起来。
Second Stage第二阶段
The $set stage calculates a new field grade based on the average field calculated in the previous stage. $set阶段根据前一阶段计算的平均字段计算新的字段等级。See $switch for more information on the $switch aggregation operator.有关$switch聚合运算符的更多信息，请参阅$switch。

After the command, the collection contains the following documents:命令发出后，集合包含以下文档：

{ "_id" : 1, "tests" : [ 95, 92, 90 ], "lastUpdate" : ISODate("2020-01-24T17:29:35.340Z"), "average" : 92, "grade" : "A" }
{ "_id" : 2, "tests" : [ 94, 88, 90 ], "lastUpdate" : ISODate("2020-01-24T17:29:35.340Z"), "average" : 90, "grade" : "A" }
{ "_id" : 3, "tests" : [ 70, 75, 82 ], "lastUpdate" : ISODate("2020-01-24T17:29:35.340Z"), "average" : 75, "grade" : "C" }

See also参阅

Updates with Aggregation Pipeline使用聚合管道进行更新

Specify arrayFilters for Array Update Operations为阵列更新操作指定arrayFilters

In the update document, use the $[<identifier>] filtered positional operator to define an identifier, which you then reference in the array filter documents. 在更新文档中，使用筛选位置运算符$[<identifier>]定义一个标识符，然后在数组筛选文档中引用该标识符。You cannot have an array filter document for an identifier if the identifier is not included in the update document.如果标识符未包含在更新文档中，则不能使用标识符的数组筛选器文档。

Note

The <identifier> must begin with a lowercase letter and contain only alphanumeric characters.<identifier>必须以小写字母开头，并且只包含字母数字字符。

You can include the same identifier multiple times in the update document; however, for each distinct identifier ($[identifier]) in the update document, you must specify exactly one corresponding array filter document. 您可以在更新文档中多次包含同一标识符；但是，对于更新文档中的每个不同标识符（$[identifier]），必须指定一个对应的数组筛选器文档。That is, you cannot specify multiple array filter documents for the same identifier. 也就是说，不能为同一标识符指定多个数组筛选器文档。For example, if the update statement includes the identifier x (possibly multiple times), you cannot specify the following for arrayFilters that includes 2 separate filter documents for x:例如，如果update语句包含标识符x（可能多次），则不能为包含x的两个单独筛选文档的arrayFilters指定以下内容：

// INVALID

[
  { "x.a": { $gt: 85 } },
  { "x.b": { $gt: 80 } }
]

However, you can specify compound conditions on the same identifier in a single filter document, such as in the following examples:但是，您可以在单个筛选文档中对同一标识符指定复合条件，如以下示例中所示：

// Example 1
[
  { $or: [{"x.a": {$gt: 85}}, {"x.b": {$gt: 80}}] }
]
// Example 2
[
  { $and: [{"x.a": {$gt: 85}}, {"x.b": {$gt: 80}}] }
]
// Example 3
[
  { "x.a": { $gt: 85 }, "x.b": { $gt: 80 } }
]

arrayFilters is not available for updates that use an aggregation pipeline.arrayFilters不适用于使用聚合管道的更新。

Update Elements Match arrayFilters Criteria更新元素匹配arrayFilters条件

To update all array elements which match a specified criteria, use the arrayFilters parameter.要更新符合指定条件的所有数组元素，请使用arrayFilters参数。

From the mongo shell, create a students collection with the following documents:从mongo shell中，创建一个包含以下文档的students集合：

db.students.insertMany([
   { "_id" : 1, "grades" : [ 95, 92, 90 ] },
   { "_id" : 2, "grades" : [ 98, 100, 102 ] },
   { "_id" : 3, "grades" : [ 95, 110, 100 ] }
])

To update all elements that are greater than or equal to 100 in the grades array, use the filtered positional operator $[<identifier>] with the arrayFilters option:要更新grades数组中大于或等于100的所有元素，请使筛选位置运算符$[<identifier>]配合arrayFilters选项：

db.students.update(
   { grades: { $gte: 100 } },
   { $set: { "grades.$[element]" : 100 } },
   {
     multi: true,
     arrayFilters: [ { "element": { $gte: 100 } } ]
   }
)

After the operation, the collection contains the following documents:操作完成后，集合包含以下文档：

{ "_id" : 1, "grades" : [ 95, 92, 90 ] }
{ "_id" : 2, "grades" : [ 98, 100, 100 ] }
{ "_id" : 3, "grades" : [ 95, 100, 100 ] }

Update Specific Elements of an Array of Documents更新文档数组的特定元素

You can also use the arrayFilters parameter to update specific document fields within an array of documents.还可以使用arrayFilters参数更新文档数组中的特定文档字段。

From the mongo shell, create a students2 collection with the following documents:在mongo shell中，使用以下文档创建students2集合：

db.students2.insertMany([
  {
    "_id" : 1,
    "grades" : [
       { "grade" : 80, "mean" : 75, "std" : 6 },
       { "grade" : 85, "mean" : 90, "std" : 4 },
       { "grade" : 85, "mean" : 85, "std" : 6 }
    ]
  }
  {
     "_id" : 2,
     "grades" : [
        { "grade" : 90, "mean" : 75, "std" : 6 },
        { "grade" : 87, "mean" : 90, "std" : 3 },
        { "grade" : 85, "mean" : 85, "std" : 4 }
     ]
  }
])

To modify the value of the mean field for all elements in the grades array where the grade is greater than or equal to 85, use the filtered positional operator $[<identifier>] with the arrayFilters:要修改等级大于或等于85的grades数组中所有元素的mean（平均值）字段，请使用筛选位置运算符$[<identifier>]配合arrayFilters选项：

db.students2.update(
   { },
   { $set: { "grades.$[elem].mean" : 100 } },
   {
     multi: true,
     arrayFilters: [ { "elem.grade": { $gte: 85 } } ]
   }
)

After the operation, the collection has the following documents:操作完成后，集合具有以下文档：

{
   "_id" : 1,
   "grades" : [
      { "grade" : 80, "mean" : 75, "std" : 6 },
      { "grade" : 85, "mean" : 100, "std" : 4 },
      { "grade" : 85, "mean" : 100, "std" : 6 }
   ]
}
{
   "_id" : 2,
   "grades" : [
      { "grade" : 90, "mean" : 100, "std" : 6 },
      { "grade" : 87, "mean" : 100, "std" : 3 },
      { "grade" : 85, "mean" : 100, "std" : 4 }
   ]
}

Specify hint for Update Operations指定更新操作的hint

New in version 4.2.版本4.2中的新功能。

From the mongo shell, create a members collection with the following documents:在mongo shell中，创建包含以下文档的members集合：

db.members.insertMany([
   { "_id" : 1, "member" : "abc123", "status" : "P", "points" :  0,  "misc1" : null, "misc2" : null },
   { "_id" : 2, "member" : "xyz123", "status" : "A", "points" : 60,  "misc1" : "reminder: ping me at 100pts", "misc2" : "Some random comment" },
   { "_id" : 3, "member" : "lmn123", "status" : "P", "points" :  0,  "misc1" : null, "misc2" : null },
   { "_id" : 4, "member" : "pqr123", "status" : "D", "points" : 20,  "misc1" : "Deactivated", "misc2" : null },
   { "_id" : 5, "member" : "ijk123", "status" : "P", "points" :  0,  "misc1" : null, "misc2" : null },
   { "_id" : 6, "member" : "cde123", "status" : "A", "points" : 86,  "misc1" : "reminder: ping me at 100pts", "misc2" : "Some random comment" }
])

Create the following indexes on the collection:在集合上创建以下索引：

db.members.createIndex( { status: 1 } )
db.members.createIndex( { points: 1 } )

The following update operation explicitly hints to use the index {status: 1 }:以下更新操作明确提示使用索引{status: 1 }：

Note

If you specify an index that does not exist, the operation errors.如果指定的索引不存在，则操作将出错。

db.members.update(
   { points: { $lte: 20 }, status: "P" },     // Query parameter
   { $set: { misc1: "Need to activate" } },   // Update document
   { multi: true, hint: { status: 1 } }       // Options
)

The update command returns the following:更新命令返回以下内容：

WriteResult({ "nMatched" : 3, "nUpserted" : 0, "nModified" : 3 })

To see the index used, run explain on the operation:要查看使用的索引，请对操作运行explain：

db.members.explain().update(
   { "points": { $lte: 20 }, "status": "P" },
   { $set: { "misc1": "Need to activate" } },
   { multi: true, hint: { status: 1 } }
)

The db.collection.explain().update() does not modify the documents.db.collection.explain().update()不会修改文档。

Override Default Write Concern覆盖默认写关注点

The following operation on a replica set specifies a write concern of "w: majority" with a wtimeout of 5000 milliseconds such that the method returns after the write propagates to a majority of the voting replica set members or the method times out after 5 seconds.以下对副本集的操作指定了一个写关注点"w: majority"，wtimeout为5000毫秒，这样该方法在写入传播到大多数投票副本集成员后返回，或者该方法在5秒后超时。

db.books.update(
   { stock: { $lte: 10 } },
   { $set: { reorder: true } },
   {
     multi: true,
     writeConcern: { w: "majority", wtimeout: 5000 }
   }
)

Specify Collation指定排序规则

Specifies the collation to use for the operation.指定要用于该操作的排序规则。

Collation allows users to specify language-specific rules for string comparison, such as rules for lettercase and accent marks.排序规则允许用户为字符串比较指定特定于语言的规则，例如字母大小写和重音符号的规则。

The collation option has the following syntax:collaction选项语法如下所示：

collation: {
   locale: <string>,
   caseLevel: <boolean>,
   caseFirst: <string>,
   strength: <int>,
   numericOrdering: <boolean>,
   alternate: <string>,
   maxVariable: <string>,
   backwards: <boolean>
}

When specifying collation, the locale field is mandatory; all other collation fields are optional. 指定排序规则时，locale字段是必需的；所有其他排序规则字段都是可选的。For descriptions of the fields, see Collation Document.有关这些字段的描述，请参阅排序规则文档。

If the collation is unspecified but the collection has a default collation (see db.createCollection()), the operation uses the collation specified for the collection.如果未指定排序规则，但集合具有默认排序规则（请参见db.createCollection()），则操作将使用为集合指定的排序规则。

If no collation is specified for the collection or for the operations, MongoDB uses the simple binary comparison used in prior versions for string comparisons.如果没有为集合或操作指定排序规则，MongoDB将使用以前版本中用于字符串比较的简单二进制比较。

You cannot specify multiple collations for an operation. 不能为一个操作指定多个排序规则。For example, you cannot specify different collations per field, or if performing a find with a sort, you cannot use one collation for the find and another for the sort.例如，不能为每个字段指定不同的排序规则，或者如果使用排序执行查找，则不能对查找使用一种排序规则，对排序使用另一种排序规则。

New in version 3.4.版本3.4中的新功能。

From the mongo shell, create a collection named myColl with the following documents:从mongo shell创建一个名为myColl的集合，其中包含以下文档：

db.myColl.insertMany(
  [
    { _id: 1, category: "café", status: "A" },
    { _id: 2, category: "cafe", status: "a" },
    { _id: 3, category: "cafE", status: "a" }
  ])

The following operation includes the collation option and sets multi to true to update all matching documents:以下操作包括排序规则选项，并将multi设置为true以更新所有匹配的文档：

db.myColl.update(
   { category: "cafe" },
   { $set: { status: "Updated" } },
   {
     collation: { locale: "fr", strength: 1 },
     multi: true
   }
);

The write result of the operation returns the following document, indicating that all three documents in the collection were updated:操作的写入结果返回以下文档，表明集合中的所有三个文档都已更新：

WriteResult({ "nMatched" : 3, "nUpserted" : 0, "nModified" : 3 })

After the operation, the collection contains the following documents:操作完成后，集合包含以下文档：

{ "_id" : 1, "category" : "café", "status" : "Updated" }
{ "_id" : 2, "category" : "cafe", "status" : "Updated" }
{ "_id" : 3, "category" : "cafE", "status" : "Updated" }

WriteResult

Successful Results成功的结果

The db.collection.update() method returns a WriteResult object that contains the status of the operation. db.collection.update()方法返回一个WriteResult对象，该对象包含操作的状态。Upon success, the WriteResult object contains the number of documents that matched the query condition, the number of documents inserted by the update, and the number of documents modified:成功后，WriteResult对象包含符合查询条件的文档数、更新插入的文档数和修改的文档数：

WriteResult({ "nMatched" : 1, "nUpserted" : 0, "nModified" : 1 })

See参阅

WriteResult.nMatched, WriteResult.nUpserted, WriteResult.nModified

Write Concern Errors写关注错误

If the db.collection.update() method encounters write concern errors, the results include the WriteResult.writeConcernError field:如果db.collection.update()方法遇到写问题错误，结果将包括WriteResult.writeConcernError字段：

Changed in version 4.4.在版本4.4中更改。

WriteResult({
   "nMatched" : 1,
   "nUpserted" : 0,
   "nModified" : 1,
   "writeConcernError": {
     "code" : 64,
     "errmsg" : "waiting for replication timed out",
     "errInfo" : {
       "wtimeout" : true,
       "writeConcern" : {
         "w" : "majority",
         "wtimeout" : 100,
         "provenance" : "getLastErrorDefaults"
       }
   }
})

The following table explains the possible values of WriteResult.writeConcernError.provenance:下表说明了WriteResult.writeConcernError.provenance的可能值：

ProvenanceDescription描述
clientSupplied The write concern was specified in the application.应用程序中指定了写入问题。
customDefault The write concern originated from a custom defined default value. 写入问题源于自定义的默认值。See setDefaultRWConcern.请参阅setDefaultRWConcern。
getLastErrorDefaults The write concern originated from the replica set’s settings.getLastErrorDefaults field.写入问题源于副本集的settings.getLastErrorDefaults字段。
implicitDefault The write concern originated from the server in absence of all other write concern specifications.在没有所有其他写关注规范的情况下，写关注源于服务器。

See also参阅

WriteResult.hasWriteConcernError()

Errors Unrelated to Write Concern与写问题无关的错误

If the db.collection.update() method encounters a non-write concern error, the results include the WriteResult.writeError field:如果db.collection.update()方法遇到非写问题错误，结果包括WriteResult.writeError字段：

WriteResult({
   "nMatched" : 0,
   "nUpserted" : 0,
   "nModified" : 0,
   "writeError" : {
      "code" : 7,
      "errmsg" : "could not contact primary for replica set shard-a"
   }
})

See also参阅

WriteResult.hasWriteError()