Query an Array查询数组¶

Query an Array with Compound Filter Conditions on the Array Elements在数组元素上查询具有复合筛选条件的数组¶

The following example queries for documents where the dim_cm array contains elements that in some combination satisfy the query conditions; e.g., one element can satisfy the greater than 15 condition and another element can satisfy the less than 20 condition, or a single element can satisfy both:下面的示例查询文档，其中dim_cm数组包含在某种组合中满足查询条件的元素；例如，一个元素可以满足大于15的条件，另一个元素可以满足小于20的条件，或者一个元素可以同时满足这两个条件：

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db.inventory.find( { dim_cm: { $gt: 15, $lt: 20 } } )

Copy the following filter into the Compass query bar and click Find:将以下筛选器复制到Compass查询栏中，然后单击“查找”：

{ dim_cm: { $gt: 15, $lt: 20 } }

cursor = db.inventory.find({"dim_cm": {"$gt": 15, "$lt": 20}})

findIterable = collection.find(and(gt("dim_cm", 15), lt("dim_cm", 20)));

const cursor = db.collection('inventory').find({
  dim_cm: { $gt: 15, $lt: 20 }
});

$cursor = $db->inventory->find([
    'dim_cm' => [
        '$gt' => 15,
        '$lt' => 20,
    ],
]);

cursor = db.inventory.find({"dim_cm": {"$gt": 15, "$lt": 20}})

findPublisher = collection.find(and(gt("dim_cm", 15), lt("dim_cm", 20)));

var builder = Builders<BsonDocument>.Filter;
var filter = builder.And(builder.Gt("dim_cm", 15), builder.Lt("dim_cm", 20));
var result = collection.Find(filter).ToList();

$cursor = $db->coll("inventory")->find(
    { "dim_cm" => { '$gt' => 15, '$lt' => 20 } }
);

client[:inventory].find(dim_cm: { '$gt' => 15,
                                  '$lt' => 20 })

findObservable = collection.find(and(gt("dim_cm", 15), lt("dim_cm", 20)))

cursor, err := coll.Find(
	context.Background(),
	bson.D{
		{"dim_cm", bson.D{
			{"$gt", 15},
			{"$lt", 20},
		}},
	})

Query for an Array Element that Meets Multiple Criteria查询满足多个条件的数组元素¶

Use $elemMatch operator to specify multiple criteria on the elements of an array such that at least one array element satisfies all the specified criteria.使用$elemMatch运算符在数组元素上指定多个条件，以便至少一个数组元素满足所有指定的条件。

The following example queries for documents where the dim_cm array contains at least one element that is both greater than ($gt) 22 and less than ($lt) 30:以下示例查询dim_cm数组中至少包含一个大于（$gt）22且小于（$lt）30的元素的文档：

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db.inventory.find( { dim_cm: { $elemMatch: { $gt: 22, $lt: 30 } } } )

Copy the following filter into the Compass query bar and click Find:将以下筛选器复制到Compass查询栏中，然后单击“查找”：

{ dim_cm: { $elemMatch: { $gt: 22, $lt: 30 } } }

cursor = db.inventory.find(
    {"dim_cm": {"$elemMatch": {"$gt": 22, "$lt": 30}}})

findIterable = collection.find(elemMatch("dim_cm", Document.parse("{ $gt: 22, $lt: 30 }")));

const cursor = db.collection('inventory').find({
  dim_cm: { $elemMatch: { $gt: 22, $lt: 30 } }
});

$cursor = $db->inventory->find([
    'dim_cm' => [
        '$elemMatch' => [
            '$gt' => 22,
            '$lt' => 30,
        ],
    ],
]);

cursor = db.inventory.find(
    {"dim_cm": {"$elemMatch": {"$gt": 22, "$lt": 30}}})

findPublisher = collection.find(elemMatch("dim_cm", Document.parse("{ $gt: 22, $lt: 30 }")));

var filter = Builders<BsonDocument>.Filter.ElemMatch<BsonValue>("dim_cm", new BsonDocument { { "$gt", 22 }, { "$lt", 30 } });
var result = collection.Find(filter).ToList();

$cursor = $db->coll("inventory")->find(
    { dim_cm => { '$elemMatch' => { '$gt' => 22, '$lt' => 30 } } }
);

client[:inventory].find(dim_cm: { '$elemMatch' => { '$gt' => 22,
                                                    '$lt' => 30 } })

findObservable = collection.find(elemMatch("dim_cm", Document("$gt" -> 22, "$lt" -> 30)))

cursor, err := coll.Find(
	context.Background(),
	bson.D{
		{"dim_cm", bson.D{
			{"$elemMatch", bson.D{
				{"$gt", 22},
				{"$lt", 30},
			}},
		}},
	})

Query for an Element by the Array Index Position按数组索引位置查询元素¶

Using dot notation, you can specify query conditions for an element at a particular index or position of the array. 使用点表示法，可以在数组的特定索引或位置为元素指定查询条件。The array uses zero-based indexing.该数组使用基于零的索引。

The following example queries for all documents where the second element in the array dim_cm is greater than 25:以下示例查询数组dim_cm中第二个元素大于25的所有文档：

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db.inventory.find( { "dim_cm.1": { $gt: 25 } } )

Copy the following filter into the Compass query bar and click Find:将以下筛选器复制到Compass查询栏中，然后单击“查找”：

{ "dim_cm.1": { $gt: 25 } }

cursor = db.inventory.find({"dim_cm.1": {"$gt": 25}})

findIterable = collection.find(gt("dim_cm.1", 25));

const cursor = db.collection('inventory').find({
  'dim_cm.1': { $gt: 25 }
});

$cursor = $db->inventory->find(['dim_cm.1' => ['$gt' => 25]]);

cursor = db.inventory.find({"dim_cm.1": {"$gt": 25}})

findPublisher = collection.find(elemMatch("dim_cm", Document.parse("{ $gt: 22, $lt: 30 }")));

var filter = Builders<BsonDocument>.Filter.Gt("dim_cm.1", 25);
var result = collection.Find(filter).ToList();

$cursor = $db->coll("inventory")->find( { "dim_cm.1" => { '$gt' => 25 } } );

client[:inventory].find('dim_cm.1' => { '$gt' => 25 })

findObservable = collection.find(gt("dim_cm.1", 25))

cursor, err := coll.Find(
	context.Background(),
	bson.D{
		{"dim_cm.1", bson.D{
			{"$gt", 25},
		}},
	})

Query an Array by Array Length按数组长度查询数组¶

Use the $size operator to query for arrays by number of elements. 使用$size运算符按元素数查询数组。For example, the following selects documents where the array tags has 3 elements.例如，下面选择数组tags有3个元素的文档。

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db.inventory.find( { "tags": { $size: 3 } } )

Copy the following filter into the Compass query bar and click Find:将以下筛选器复制到Compass查询栏中，然后单击“查找”：

{ "tags": { $size: 3 } }

cursor = db.inventory.find({"tags": {"$size": 3}})

findIterable = collection.find(size("tags", 3));

const cursor = db.collection('inventory').find({
  tags: { $size: 3 }
});

$cursor = $db->inventory->find(['tags' => ['$size' => 3]]);

cursor = db.inventory.find({"tags": {"$size": 3}})

findPublisher = collection.find(size("tags", 3));

var filter = Builders<BsonDocument>.Filter.Size("tags", 3);
var result = collection.Find(filter).ToList();

$cursor = $db->coll("inventory")->find( { tags => { '$size' => 3 } } );

client[:inventory].find(tags: { '$size' => 3 })

findObservable = collection.find(size("tags", 3))

cursor, err := coll.Find(
	context.Background(),
	bson.D{
		{"tags", bson.D{
			{"$size", 3},
		}},
	})