Query Documents查询文档

To select all documents in the collection, pass an empty document as the query filter parameter to the find method. The query filter parameter determines the select criteria:要选择集合中的所有文档，请将一个空文档作为查询筛选器参数传递给find方法。查询筛选器参数确定选择条件：

To select all documents in the collection, pass an empty document as the query filter parameter to the query bar. 要选择集合中的所有文档，请将一个空文档作为查询筛选器参数传递给查询栏。The query filter parameter determines the select criteria:查询筛选器参数确定选择条件：

To select all documents in the collection, pass an empty document as the query filter parameter to the find method. The query filter parameter determines the select criteria:要选择集合中的所有文档，请将一个空文档作为查询筛选器参数传递给find方法。查询筛选器参数确定选择条件：

To select all documents in the collection, pass an empty document as the query filter parameter to the find method. The query filter parameter determines the select criteria:要选择集合中的所有文档，请将一个空文档作为查询筛选器参数传递给find方法。查询筛选器参数确定选择条件：

To select all documents in the collection, pass an empty document as the query filter parameter to the find method. The query filter parameter determines the select criteria:要选择集合中的所有文档，请将一个空文档作为查询筛选器参数传递给find方法。查询筛选器参数确定选择条件：

To select all documents in the collection, pass an empty document as the query filter parameter to the find method. The query filter parameter determines the select criteria:要选择集合中的所有文档，请将一个空文档作为查询筛选器参数传递给find方法。查询筛选器参数确定选择条件：

To select all documents in the collection, pass an empty document as the query filter parameter to the find method. The query filter parameter determines the select criteria:要选择集合中的所有文档，请将一个空文档作为查询筛选器参数传递给find方法。查询筛选器参数确定选择条件：

To select all documents in the collection, pass an empty document as the query filter parameter to the find method. The query filter parameter determines the select criteria:要选择集合中的所有文档，请将一个空文档作为查询筛选器参数传递给find方法。查询筛选器参数确定选择条件：

To select all documents in the collection, pass an empty document as the query filter parameter to the find method. The query filter parameter determines the select criteria:要选择集合中的所有文档，请将一个空文档作为查询筛选器参数传递给find方法。查询筛选器参数确定选择条件：

To select all documents in the collection, pass an empty document as the query filter parameter to the find method. The query filter parameter determines the select criteria:要选择集合中的所有文档，请将一个空文档作为查询筛选器参数传递给find方法。查询筛选器参数确定选择条件：

To select all documents in the collection, pass an empty document as the query filter parameter to the find method. The query filter parameter determines the select criteria:要选择集合中的所有文档，请将一个空文档作为查询筛选器参数传递给find方法。查询筛选器参数确定选择条件：

To select all documents in the collection, pass an empty document as the query filter parameter to the find method. The query filter parameter determines the select criteria:要选择集合中的所有文档，请将一个空文档作为查询筛选器参数传递给find方法。查询筛选器参数确定选择条件：

To select all documents in the collection, pass an empty document as the query filter parameter to the find method. The query filter parameter determines the select criteria:要选择集合中的所有文档，请将一个空文档作为查询筛选器参数传递给find方法。查询筛选器参数确定选择条件：

To select all documents in the collection, pass an empty document as the query filter parameter to the find method. The query filter parameter determines the select criteria:要选择集合中的所有文档，请将一个空文档作为查询筛选器参数传递给find方法。查询筛选器参数确定选择条件：

db.inventory.find( {} )

mongoc_collection_t *collection;
bson_t *filter;
mongoc_cursor_t *cursor;

collection = mongoc_database_get_collection (db, "inventory");
filter = BCON_NEW (NULL);
cursor = mongoc_collection_find_with_opts (collection, filter, NULL, NULL);

Be sure to also clean up any open resources by calling the following methods, as appropriate:请确保根据需要调用以下方法来清理任何开放资源：

• bson_destroy
• mongoc_bulk_operation_destroy
• mongoc_collection_destroy
• mongoc_cursor_destroy,

var filter = Builders<BsonDocument>.Filter.Empty;
var result = collection.Find(filter).ToList();

cursor, err := coll.Find(
	context.TODO(),
	bson.D{},
)

FindPublisher<Document> findPublisher = collection.find(new Document());

FindIterable<Document> findIterable = collection.find(new Document());

val flowInsertMany = collection
    .find(empty())

cursor = db.inventory.find({})

const cursor = db.collection('inventory').find({});

$cursor = $db->inventory->find([]);

cursor = db.inventory.find({})

client[:inventory].find({})

var findObservable = collection.find(Document())

For more information on the syntax of the method, see find().有关该方法语法的更多信息，请参阅find()。

For more information on the MongoDB Compass query bar, see Query Bar.有关MongoDB Compass查询栏的更多信息，请参阅查询栏。

For more information on the syntax of the method, see mongoc_collection_find_with_opts.有关该方法语法的更多信息，请参阅mongoc_collection_find_with_opts。

For more information on the syntax of the method, see Find().有关该方法语法的更多信息，请参阅Find()。

For more information on the syntax of the method, see com.mongodb.reactivestreams.client.MongoCollection.find.有关该方法语法的更多信息，请参阅com.mongodb.reactivestreams.client.MongoCollection.find。

For more information on the syntax of the method, see com.mongodb.client.MongoCollection.find.

For more information on the syntax of the method, see MongoCollection.find().有关该方法语法的更多信息，请参阅MongoCollection.find()。

To see supported options for the find() method, see find().要查看find()方法的支持选项，请参阅find()。

For more information on the syntax of the method, see find().有关该方法语法的更多信息，请参阅find()。

For more information on the syntax of the method, see find.有关该方法语法的更多信息，请参阅find。

For more information on the syntax of the method, see find().有关该方法语法的更多信息，请参阅find()。

For more information on the syntax of the method, see collection.find().有关该方法语法的更多信息，请参阅collection.find()。

To specify equality conditions, use <field>:<value> expressions in the query filter document:要指定相等条件，请在查询筛选器文档中使用<field>:<value>表达式：

{ <field1>: <value1>, ... }

To specify equality conditions, use <field>:<value> expressions in the query filter document:要指定相等条件，请在查询筛选器文档中使用<field>:<value>表达式：

{ <field1>: <value1>, ... }

To specify equality conditions, use <field>:<value> expressions in the query filter document:要指定相等条件，请在查询筛选器文档中使用<field>:<value>表达式：

{ <field1>: <value1>, ... }

To specify equality conditions, construct a filter using the Eq method:要指定相等条件，请使用Eq方法构造一个筛选器：

Builders<BsonDocument>.Filter.Eq(<field>, <value>);

To specify equality conditions, use the com.mongodb.client.model.Filters.eq method to create the query filter document:要指定相等条件，请使用com.mongodb.client.model.Filters.eq方法创建查询筛选器文档：

and(eq(<field1>, <value1>), eq(<field2>, <value2>) ...)

To specify equality conditions, use the com.mongodb.client.model.Filters.eq_ method to create the query filter document:要指定相等条件，请使用com.mongodb.client.model.Filters.eq_方法创建查询筛选器文档：

and(eq(<field1>, <value1>), eq(<field2>, <value2>) ...)

To specify equality conditions, use the Filters.eq() method to create the query filter document:要指定相等条件，请使用Filters.eq()方法创建查询筛选器文档：

and(eq(<field1>, <value1>), eq(<field2>, <value2>) ...)

To specify equality conditions, use <field>:<value> expressions in the query filter document:要指定相等条件，请在查询筛选器文档中使用<field>:<value>表达式：

{ <field1>: <value1>, ... }

To specify equality conditions, use <field>:<value> expressions in the query filter document:要指定相等条件，请在查询筛选器文档中使用<field>:<value>表达式：

{ <field1>: <value1>, ... }

To specify equality conditions, use <field> => <value> expressions in the query filter document:要指定相等条件，请在查询筛选器文档中使用<field> => <value>表达式：

[ <field1> => <value1>, ... ]

To specify equality conditions, use <field>:<value> expressions in the query filter document:要指定相等条件，请在查询筛选器文档中使用<field>:<value>表达式：

{ <field1>: <value1>, ... }

To specify equality conditions, use <field> => <value> expressions in the query filter document:要指定相等条件，请在查询筛选器文档中使用<field> => <value>表达式：

{ <field1> => <value1>, ... }

To specify equality conditions, use the com.mongodb.client.model.Filters.eq_ method to create the query filter document:要指定相等条件，请使用com.mongodb.client.model.Filters.eq_方法创建查询筛选器文档：

and(equal(<field1>, <value1>), equal(<field2>, <value2>) ...)

db.inventory.find( { status: "D" } )

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：

{ status: "D" }

mongoc_collection_t *collection;
bson_t *filter;
mongoc_cursor_t *cursor;

collection = mongoc_database_get_collection (db, "inventory");
filter = BCON_NEW ("status", BCON_UTF8 ("D"));
cursor = mongoc_collection_find_with_opts (collection, filter, NULL, NULL);

var filter = Builders<BsonDocument>.Filter.Eq("status", "D");
var result = collection.Find(filter).ToList();

cursor, err := coll.Find(
	context.TODO(),
	bson.D{{"status", "D"}},
)

findPublisher = collection.find(eq("status", "D"));

findIterable = collection.find(eq("status", "D"));

val findFlow = collection
    .find(eq("status", "D"))

cursor = db.inventory.find({"status": "D"})

const cursor = db.collection('inventory').find({ status: 'D' });

$cursor = $db->inventory->find(['status' => 'D']);

cursor = db.inventory.find({"status": "D"})

client[:inventory].find(status: 'D')

findObservable = collection.find(equal("status", "D"))

A query filter document can use the query operators to specify conditions in the following form:查询筛选文档可以使用查询运算符以以下形式指定条件：

{ <field1>: { <operator1>: <value1> }, ... }

A query filter document can use the query operators to specify conditions in the following form:查询筛选文档可以使用查询运算符以以下形式指定条件：

{ <field1>: { <operator1>: <value1> }, ... }

A query filter document can use the query operators to specify conditions in the following form:查询筛选文档可以使用查询运算符以以下形式指定条件：

{ <field1>: { <operator1>: <value1> }, ... }

In addition to the equality filter, MongoDB provides various query operators to specify filter conditions. 除了等式筛选器外，MongoDB还提供了各种查询运算符来指定筛选条件。Use the FilterDefinitionBuilder methods to create a filter document. For example:使用FilterDefinitionBuilder方法创建筛选器文档。例如：

var builder = Builders<BsonDocument>.Filter;
builder.And(builder.Eq(<field1>, <value1>), builder.Lt(<field2>, <value2>));

In addition to the equality filter, MongoDB provides various query operators to specify filter conditions. 除了等式筛选器外，MongoDB还提供了各种查询运算符来指定筛选条件。Use the bson package to create query operators for filter documents. For example:使用bson包为筛选文档创建查询运算符。例如：

filter := bson.D{
    {"$and", bson.A{
        bson.D{{"field1", bson.D{{"$eq", value1}}}},
        bson.D{{"field2", bson.D{{"$lt", value2}}}},
    }},
}

In addition to the equality condition, MongoDB provides various query operators to specify filter conditions. 除了相等条件外，MongoDB还提供了各种查询运算符来指定筛选条件。Use the com.mongodb.client.model.Filters helper methods to facilitate the creation of filter documents. For example:使用com.mongodb.client.model.Filters辅助方法来简化筛选器文档的创建。例如：

and(gte(<field1>, <value1>), lt(<field2>, <value2>), eq(<field3>, <value3>))

In addition to the equality condition, MongoDB provides various query operators to specify filter conditions. 除了相等条件外，MongoDB还提供了各种查询运算符来指定筛选条件。Use the com.mongodb.client.model.Filters helper methods to facilitate the creation of filter documents. For example:使用com.mongodb.client.model.Filters辅助方法来简化筛选器文档的创建。例如：

and(gte(<field1>, <value1>), lt(<field2>, <value2>), eq(<field3>, <value3>))

In addition to the equality condition, MongoDB provides various query operators to specify filter conditions. Use the com.mongodb.client.model.Filters helper methods to facilitate the creation of filter documents. For example:

and(gte(<field1>, <value1>), lt(<field2>, <value2>), eq(<field3>, <value3>))

A query filter document can use the query operators to specify conditions in the following form:查询筛选文档可以使用查询运算符以以下形式指定条件：

{ <field1>: { <operator1>: <value1> }, ... }

A query filter document can use the query operators to specify conditions in the following form:查询筛选文档可以使用查询运算符以以下形式指定条件：

{ <field1>: { <operator1>: <value1> }, ... }

A query filter document can use the query operators to specify conditions in the following form:查询筛选文档可以使用查询运算符以以下形式指定条件：

[ <field1> => [ <operator1> => <value1> ], ... ]

A query filter document can use the query operators to specify conditions in the following form:查询筛选文档可以使用查询运算符以以下形式指定条件：

{ <field1>: { <operator1>: <value1> }, ... }

A query filter document can use the query operators to specify conditions in the following form:查询筛选文档可以使用查询运算符以以下形式指定条件：

{ <field1> => { <operator1> => <value1> }, ... }

In addition to the equality condition, MongoDB provides various query operators to specify filter conditions. 除了相等条件外，MongoDB还提供了各种查询运算符来指定筛选条件。Use the com.mongodb.client.model.Filters_ helper methods to facilitate the creation of filter documents. For example:使用com.mongodb.client.model.Filters_助手方法来简化筛选器文档的创建。例如：

and(gte(<field1>, <value1>), lt(<field2>, <value2>), equal(<field3>, <value3>))

db.inventory.find( { status: { $in: [ "A", "D" ] } } )

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”：

{ status: { $in: [ "A", "D" ] } }

mongoc_collection_t *collection;
bson_t *filter;
mongoc_cursor_t *cursor;

collection = mongoc_database_get_collection (db, "inventory");
filter = BCON_NEW (
   "status", "{",
   "$in", "[",
   BCON_UTF8 ("A"), BCON_UTF8 ("D"),
   "]",
   "}");
cursor = mongoc_collection_find_with_opts (collection, filter, NULL, NULL);

var filter = Builders<BsonDocument>.Filter.In("status", new[] { "A", "D" });
var result = collection.Find(filter).ToList();

cursor, err := coll.Find(
	context.TODO(),
	bson.D{{"status", bson.D{{"$in", bson.A{"A", "D"}}}}})

findPublisher = collection.find(in("status", "A", "D"));

findIterable = collection.find(in("status", "A", "D"));

val findFlow = collection
    .find(`in`("status", "A", "D"))

cursor = db.inventory.find({"status": {"$in": ["A", "D"]}})

const cursor = db.collection('inventory').find({
  status: { $in: ['A', 'D'] }
});

$cursor = $db->inventory->find(['status' => ['$in' => ['A', 'D']]]);

cursor = db.inventory.find({"status": {"$in": ["A", "D"]}})

client[:inventory].find(status: { '$in' => [ 'A', 'D' ]})

findObservable = collection.find(in("status", "A", "D"))

db.inventory.find( { status: "A", qty: { $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”：

{ status: "A", qty: { $lt: 30 } }

mongoc_collection_t *collection;
bson_t *filter;
mongoc_cursor_t *cursor;

collection = mongoc_database_get_collection (db, "inventory");
filter = BCON_NEW (
   "status", BCON_UTF8 ("A"),
   "qty", "{",
   "$lt", BCON_INT64 (30),
   "}");
cursor = mongoc_collection_find_with_opts (collection, filter, NULL, NULL);

var builder = Builders<BsonDocument>.Filter;
var filter = builder.And(builder.Eq("status", "A"), builder.Lt("qty", 30));
var result = collection.Find(filter).ToList();

cursor, err := coll.Find(
	context.TODO(),
	bson.D{
		{"status", "A"},
		{"qty", bson.D{{"$lt", 30}}},
	})

findPublisher = collection.find(and(eq("status", "A"), lt("qty", 30)));

findIterable = collection.find(and(eq("status", "A"), lt("qty", 30)));

val findFlow = collection
    .find(and(eq("status", "A"), lt("qty", 30)))

cursor = db.inventory.find({"status": "A", "qty": {"$lt": 30}})

const cursor = db.collection('inventory').find({
  status: 'A',
  qty: { $lt: 30 }
});

$cursor = $db->inventory->find([
    'status' => 'A',
    'qty' => ['$lt' => 30],
]);

cursor = db.inventory.find({"status": "A", "qty": {"$lt": 30}})

client[:inventory].find(status: 'A', qty: { '$lt' => 30 })

findObservable = collection.find(and(equal("status", "A"), lt("qty", 30)))

db.inventory.find( { $or: [ { status: "A" }, { qty: { $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”：

{ $or: [ { status: "A" }, { qty: { $lt: 30 } } ] }

mongoc_collection_t *collection;
bson_t *filter;
mongoc_cursor_t *cursor;

collection = mongoc_database_get_collection (db, "inventory");
filter = BCON_NEW (
   "$or", "[",
   "{",
   "status", BCON_UTF8 ("A"),
   "}","{",
   "qty", "{",
   "$lt", BCON_INT64 (30),
   "}",
   "}",
   "]");
cursor = mongoc_collection_find_with_opts (collection, filter, NULL, NULL);

var builder = Builders<BsonDocument>.Filter;
var filter = builder.Or(builder.Eq("status", "A"), builder.Lt("qty", 30));
var result = collection.Find(filter).ToList();

cursor, err := coll.Find(
	context.TODO(),
	bson.D{
		{"$or",
			bson.A{
				bson.D{{"status", "A"}},
				bson.D{{"qty", bson.D{{"$lt", 30}}}},
			}},
	})

findPublisher = collection.find(or(eq("status", "A"), lt("qty", 30)));

findIterable = collection.find(or(eq("status", "A"), lt("qty", 30)));

val findFlow = collection
    .find(or(eq("status", "A"), lt("qty", 30)))

cursor = db.inventory.find({"$or": [{"status": "A"}, {"qty": {"$lt": 30}}]})

const cursor = db.collection('inventory').find({
  $or: [{ status: 'A' }, { qty: { $lt: 30 } }]
});

$cursor = $db->inventory->find([
    '$or' => [
        ['status' => 'A'],
        ['qty' => ['$lt' => 30]],
    ],
]);

cursor = db.inventory.find({"$or": [{"status": "A"}, {"qty": {"$lt": 30}}]})

client[:inventory].find('$or' => [{ status: 'A' },
                                  { qty: { '$lt' => 30 } }
                                 ])

findObservable = collection.find(or(equal("status", "A"), lt("qty", 30)))

db.inventory.find( {
     status: "A",
     $or: [ { qty: { $lt: 30 } }, { item: /^p/ } ]
} )

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”：

{ status: "A", $or: [ { qty: { $lt: 30 } }, { item: /^p/ } ] }

mongoc_collection_t *collection;
bson_t *filter;
mongoc_cursor_t *cursor;

collection = mongoc_database_get_collection (db, "inventory");
filter = BCON_NEW (
   "status", BCON_UTF8 ("A"),
   "$or", "[",
   "{",
   "qty", "{",
   "$lt", BCON_INT64 (30),
   "}",
   "}","{",
   "item", BCON_REGEX ("^p", ""),
   "}",
   "]");
cursor = mongoc_collection_find_with_opts (collection, filter, NULL, NULL);

var builder = Builders<BsonDocument>.Filter;
var filter = builder.And(
    builder.Eq("status", "A"),
    builder.Or(builder.Lt("qty", 30), builder.Regex("item", new BsonRegularExpression("^p"))));
var result = collection.Find(filter).ToList();

cursor, err := coll.Find(
	context.TODO(),
	bson.D{
		{"status", "A"},
		{"$or", bson.A{
			bson.D{{"qty", bson.D{{"$lt", 30}}}},
			bson.D{{"item", bson.Regex{Pattern: "^p", Options: ""}}},
		}},
	})

findPublisher = collection.find(
        and(eq("status", "A"),
                or(lt("qty", 30), regex("item", "^p")))
);

findIterable = collection.find(
        and(eq("status", "A"),
                or(lt("qty", 30), regex("item", "^p")))
);

val findFlow = collection
    .find(
        and(eq("status", "A"),
            or(lt("qty", 30), regex("item", "^p")))
    )

cursor = db.inventory.find(
    {"status": "A", "$or": [{"qty": {"$lt": 30}}, {"item": {"$regex": "^p"}}]}
)

const cursor = db.collection('inventory').find({
  status: 'A',
  $or: [{ qty: { $lt: 30 } }, { item: { $regex: '^p' } }]
});

$cursor = $db->inventory->find([
    'status' => 'A',
    '$or' => [
        ['qty' => ['$lt' => 30]],
        // Alternatively: ['item' => new \MongoDB\BSON\Regex('^p')]
        ['item' => ['$regex' => '^p']],
    ],
]);

cursor = db.inventory.find(
    {"status": "A", "$or": [{"qty": {"$lt": 30}}, {"item": {"$regex": "^p"}}]}
)

client[:inventory].find(status: 'A',
                        '$or' => [{ qty: { '$lt' => 30 } },
                                  { item: { '$regex' => BSON::Regexp::Raw.new('^p') } }
                        ])

findObservable = collection.find(and(
  equal("status", "A"),
  or(lt("qty", 30), regex("item", "^p")))
)

The following can also read documents from a collection:以下人员也可以从集合中读取文档：

• The db.collection.findOne() methoddb.collection.findOne()方法
• The $match pipeline stage in an aggregation pipeline. The $match pipeline stage provides access to MongoDB queries聚合管道中的$match管道阶段。$match管道阶段提供对MongoDB查询的访问

In addition to filter, MongoDB Compass also allows you to pass the following options to the query bar:除了filter，MongoDB Compass还允许您将以下选项传递给查询栏：

The following method can also read documents from a collection:以下方法也可以从集合中读取文档：

• mongoc_find_and_modify_opts_t

The following can also read documents from a collection:以下人员也可以从集合中读取文档：

• MongoCollection.FindOne()
• In aggregation pipeline, the $match pipeline stage provides access to MongoDB queries. 在聚合管道中，$match管道阶段提供对MongoDB查询的访问。See the MongoDB C# driver's LINQ documentation.请参阅MongoDB C#驱动程序的LINQ文档。

The following can also read documents from a collection:以下人员也可以从集合中读取文档：

• Collection.FindOne
• In aggregation pipeline, the $match pipeline stage provides access to MongoDB queries. 在聚合管道中，$match管道阶段提供对MongoDB查询的访问。See Collection.Aggregate.请参见Collection.Aggregate。

The following can also read documents from a collection:以下人员也可以从集合中读取文档：

• In the aggregation pipeline, the $match pipeline stage provides access to MongoDB queries. 在聚合管道中，$match管道阶段提供对MongoDB查询的访问。See the Java Synchronous Driver Aggregation Examples.请参阅Java同步驱动程序聚合示例。

The following methods can also read documents from a collection:以下方法也可以从集合中读取文档：

• In an aggregation pipeline, the $match pipeline stage allows you to perform MongoDB queries. 在聚合管道中，$match管道阶段允许您执行MongoDB查询。See the Kotlin Coroutine Driver Find Operation Examples to learn more.请参阅Kotlin协程驱动程序查找操作示例以了解更多信息。

The following can also read documents from a collection:以下人员也可以从集合中读取文档：

• Collection.findOne()
• In aggregation pipeline, the $match pipeline stage provides access to MongoDB queries. 在聚合管道中，$match管道阶段提供对MongoDB查询的访问。See the MongoDB Node.js Driver's aggregation tutorial.请参阅MongoDB Node.js驱动程序的聚合教程。

The following can also read documents from a collection:以下人员也可以从集合中读取文档：

• MongoDB\\Collection::findOne()
• In aggregation pipeline, the $match pipeline stage provides access to MongoDB queries. 在聚合管道中，$match管道阶段提供对MongoDB查询的访问。See the MongoDB PHP Library's aggregation example.请参阅MongoDB PHP库的聚合示例。

The following can also read documents from a collection:以下人员也可以从集合中读取文档：

• pymongo.collection.Collection.find_one
• In an aggregation pipeline, the $match pipeline stage provides access to MongoDB queries. 在聚合管道中，$match管道阶段提供对MongoDB查询的访问。See the PyMongo Aggregation Examples.请参阅PyMongo聚合示例。

The following can also read documents from a collection:以下人员也可以从集合中读取文档：

• In aggregation pipeline, the $match pipeline stage provides access to MongoDB queries. 在聚合管道中，$match管道阶段提供对MongoDB查询的访问。See the MongoDB Ruby driver's aggregation examples.请参阅MongoDB Ruby驱动程序的聚合示例。

The following can also read documents from a collection:以下人员也可以从集合中读取文档：

• In aggregation pipeline, the $match pipeline stage provides access to MongoDB queries. 在聚合管道中，$match管道阶段提供对MongoDB查询的访问。See the MongoDB Scala driver's aggregate method.请参阅MongoDB Scala驱动程序的聚合方法。