Update Documents更新文件¶

The following example uses the Collection.updateOne() method on the inventory collection to update the first document where item equals "paper":以下示例使用inventory集合上的Collection.updateOne()方法更新第一个其item等于"paper"的文档：

await db.collection('inventory').updateOne(
  { item: 'paper' },
  {
    $set: { 'size.uom': 'cm', status: 'P' },
    $currentDate: { lastModified: true }
  }
);

The update operation:更新操作：

• uses the $set operator to update the value of the size.uom field to "cm" and the value of the status field to "P",使用$set运算符将size.uom字段的值更新为"cm"，将status字段的值更新为"P"，
• uses the $currentDate operator to update the value of the lastModified field to the current date. 使用$currentDate运算符将lastModified字段的值更新为当前日期。If lastModified field does not exist, $currentDate will create the field. 如果lastModified字段不存在，$currentDate将创建该字段。See $currentDate for details.有关详细信息，请参阅$currentDate。

Update Multiple Documents更新多个文档

The following example uses the Collection.updateMany() method on the inventory collection to update all documents where qty is less than 50:以下示例使用inventory集合上的Collection.updateMany()方法更新qty小于50的所有文档：

await db.collection('inventory').updateMany(
  { qty: { $lt: 50 } },
  {
    $set: { 'size.uom': 'in', status: 'P' },
    $currentDate: { lastModified: true }
  }
);

The update operation:更新操作：

• uses the $set operator to update the value of the size.uom field to "in" and the value of the status field to "P",使用$set运算符将size.uom字段的值更新为"in"，将status字段的值更新为"P"，
• uses the $currentDate operator to update the value of the lastModified field to the current date. 使用$currentDate运算符将lastModified字段的值更新为当前日期。If lastModified field does not exist, $currentDate will create the field. 如果lastModified字段不存在，$currentDate将创建该字段。See $currentDate for details.有关详细信息，请参阅$currentDate。

Replace a Document替换一个文档

To replace the entire content of a document except for the _id field, pass an entirely new document as the second argument to Collection.replaceOne().要替换文档中除_id字段之外的全部内容，请将全新文档作为第二个参数传递给Collection.replaceOne()。

When replacing a document, the replacement document must consist of only field/value pairs; i.e. do not include update operators expressions.替换文档时，替换文档必须仅包含字段/值对；亦即，不包括更新运算符表达式。

The replacement document can have different fields from the original document. 替换文档可以具有与原始文档不同的字段。In the replacement document, you can omit the _id field since the _id field is immutable; however, if you do include the _id field, it must have the same value as the current value.在替换文档中，您可以省略_id字段，因为_id字段是不可变的；但是，如果确实包含_id字段，则该字段的值必须与当前值相同。

The following example replaces the first document from the inventory collection where item: "paper":以下示例替换inventory集合中的第一个满足item: "paper"的文档：

Upsert Option选项

If updateOne(), updateMany(), or replaceOne() include upsert : true in the options parameter document and no documents match the specified filter, then the operation creates a new document and inserts it. 如果updateOne()、updateMany()或replaceOne()在options参数文档中包含upsert: true，并且没有与指定筛选器匹配的文档，则该操作将创建一个新文档并将其插入。If there are matching documents, then the operation modifies or replaces the matching document or documents.如果存在匹配文档，则该操作将修改或替换匹配文档。

For details on the new document created, see the individual reference pages for the methods.有关创建的新文档的详细信息，请参阅方法的各个参考页。