Query for Null or Missing Fields查询空字段或缺少字段

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➤ Use the Select your language drop-down menu in the upper-right to set the language of the following examples.使用右上角的“选择语言”下拉菜单设置以下示例的语言。

Different query operators in MongoDB treat null values differently.MongoDB中的不同查询运算符对null值的处理方式不同。

This page provides examples of operations that query for null values using the db.collection.find() method in mongosh. 本页提供了使用mongosh中的db.collection.find()方法查询空值的操作示例。The examples on this page use the inventory collection. 本页上的示例使用inventory集合。To populate the inventory collection, run the following:要填充inventory集合，请运行以下操作：

This page provides examples of operations that query for null values using MongoDB Compass. 本页提供使用MongoDB Compass查询null值的操作示例。The examples on this page use the inventory collection. 本页上的示例使用inventory集合。Populate the inventory collection with the following documents:使用以下文档填充inventory集合：

This page provides examples of operations that query for null values using the MongoCollection.Find() method in the MongoDB C# Driver. 本页提供了使用MongoDB C#驱动程序中的MongoCollection.Find()方法查询空值的操作示例。The examples on this page use the inventory collection. 本页上的示例使用inventory集合。To populate the inventory collection, run the following:要填充inventory集合，请运行以下操作：

This page provides examples of operations that query for null values using the Collection.Find function in the MongoDB Go Driver. The examples on this page use the inventory collection. To populate the inventory collection, run the following:

This page provides examples of operations that query for null values using the com.mongodb.reactivestreams.client.MongoCollection.find method in the MongoDB Java Reactive Streams Driver.

The examples on this page use the inventory collection. To populate the inventory collection, run the following:

This page provides examples of operations that query for null values using the com.mongodb.client.MongoCollection.find method in the MongoDB Java Synchronous Driver.

Tip提示

The driver provides com.mongodb.client.model.Filters helper methods to facilitate the creation of filter documents. The examples on this page use these methods to create the filter documents.

The examples on this page use the inventory collection. 本页上的示例使用inventory集合。To populate the inventory collection, run the following:要填充inventory集合，请运行以下操作：

This page provides examples of operations that query for null values using the motor.motor_asyncio.AsyncIOMotorCollection.find method in the Motor driver. The examples on this page use the inventory collection. To populate the inventory collection, run the following:

This page provides examples of operations that query for null values using the Collection.find() method in the MongoDB Node.js Driver. 本页提供了使用MongoDB Node.js驱动程序中的Collection.find()方法查询空值的操作示例。The examples on this page use the inventory collection. 本页上的示例使用inventory集合。To populate the inventory collection, run the following:要填充inventory集合，请运行以下操作：

This page provides examples of operations that query for null values using the MongoDB::Collection::find() method in the MongoDB Perl Driver. The examples on this page use the inventory collection. To populate the inventory collection, run the following:

This page provides examples of operations that query for null values using the MongoDB\\Collection::find() method in the MongoDB PHP Library. The examples on this page use the inventory collection. To populate the inventory collection, run the following:

This page provides examples of operations that query for null values using the pymongo.collection.Collection.find method in the PyMongo Python driver. The examples on this page use the inventory collection. To populate the inventory collection, run the following:

This page provides examples of operations that query for null values using the Mongo::Collection#find() method in the MongoDB Ruby Driver. The examples on this page use the inventory collection. To populate the inventory collection, run the following:

This page provides examples of operations that query for null values using the collection.find() method in the MongoDB Scala Driver. The examples on this page use the inventory collection. To populate the inventory collection, run the following:

Important重要

Use BsonNull.Value with the MongoDB C# driver to query for null or missing fields in MongoDB.使用BsonNull.Value和MongoDB C#驱动程序来查询MongoDB中的null或缺失字段。

Important重要

Use nil with the MongoDB Go driver to query for null or missing fields in MongoDB.

Important重要

Use None with the Motor driver to query for null or missing fields in MongoDB.

Important重要

Use undef with the MongoDB Perl driver to query for null or missing fields in MongoDB.

Important重要

Use None with the PyMongo Python driver to query for null or missing fields in MongoDB.

Important重要

Use nil with the MongoDB Ruby driver to query for null or missing fields in MongoDB.

Important重要

Use BsonNull() with the MongoDB Scala driver to query for null or missing fields in MongoDB.

db.inventory.insertMany([
   { _id: 1, item: null },
   { _id: 2 }
])

You can run the operation in the web shell below:您可以在下面的web shell中运行该操作：

You can run the operation in the web shell below:您可以在下面的web shell中运行该操作：

[
   { "_id": 1, "item": null },
   { "_id": 2 }
]

For instructions on inserting documents in MongoDB Compass, see Insert Documents.有关在MongoDB Compass中插入文档的说明，请参阅插入文档。

var documents = new[]
{
    new BsonDocument { { "_id", 1 }, { "item", BsonNull.Value } },
    new BsonDocument { { "_id", 2 } }
};
collection.InsertMany(documents);
docs := []interface{}{
	bson.D{
		{"_id", 1},
		{"item", nil},
	},
	bson.D{
		{"_id", 2},
	},
}


result, err := coll.InsertMany(context.TODO(), docs)
Publisher<Success> insertManyPublisher = collection.insertMany(asList(
        Document.parse("{'_id': 1, 'item': null}"),
        Document.parse("{'_id': 2}")
));
collection.insertMany(asList(
        Document.parse("{'_id': 1, 'item': null}"),
        Document.parse("{'_id': 2}")
));
await db.inventory.insert_many([{"_id": 1, "item": None}, {"_id": 2}])
await db.collection('inventory').insertMany([{ _id: 1, item: null }, { _id: 2 }]);
$db->coll("inventory")->insert_many( [ { _id => 1, item => undef }, { _id => 2 } ] );
$insertManyResult = $db->inventory->insertMany([
    ['_id' => 1, 'item' => null],
    ['_id' => 2],
]);
db.inventory.insert_many([{"_id": 1, "item": None}, {"_id": 2}])
client[:inventory].insert_many([{ _id: 1, item: nil },
                                { _id: 2 }])
collection.insertMany(Seq(
  Document("""{"_id": 1, "item": null}"""),
  Document("""{"_id": 2}""")
)).execute()

Equality Filter等式筛选器

The { item : null } query matches documents that either contain the item field whose value is null or that do not contain the item field.{ item : null }查询匹配包含值为null的item字段或不包含item字段的文档。

The { item : null } query matches documents that either contain the item field whose value is null or that do not contain the item field.{ item : null }查询匹配包含值为null的项字段或不包含项字段的文档。

The Eq("item", BsonNull.Value) query using the FilterDefinitionBuilder.Eq() method matches documents that either contain the item field whose value is null or that do not contain the item field.

The item => nil query matches documents that either contain the item field whose value is nil or that do not contain the item field.

The eq("item", null) query matches documents that either contain the item field whose value is null or that do not contain the item field.

The eq("item", null) query matches documents that either contain the item field whose value is null or that do not contain the item field.

The { item : None } query matches documents that either contain the item field whose value is null or that do not contain the item field.

The { item : null } query matches documents that either contain the item field whose value is null or that do not contain the item field.

The { item => undef } query matches documents that either contain the item field whose value is null or that do not contain the item field.

The [ item => undef ] query matches documents that either contain the item field whose value is null or that do not contain the item field.

The { item : None } query matches documents that either contain the item field whose value is null or that do not contain the item field.

The { item => nil } query matches documents that either contain the item field whose value is nil or that do not contain the item field.

The equal("item", BsonNull) query matches documents that either contain the item field whose value is null or that do not contain the item field.

db.inventory.find( { item: null } )

Copy the following query filter document into the query bar and click Find:将以下查询筛选器文档复制到查询栏中，然后单击“查找”：

{ item: null }
Query null value or missing field
var filter = Builders<BsonDocument>.Filter.Eq("item", BsonNull.Value);
var result = collection.Find(filter).ToList();
cursor, err := coll.Find(
	context.TODO(),
	bson.D{
		{"item", nil},
	})
FindPublisher<Document> findPublisher = collection.find(eq("item", null));
FindIterable<Document> findIterable = collection.find(eq("item", null));
cursor = db.inventory.find({"item": None})
const cursor = db.collection('inventory').find({
  item: null
});
$cursor = $db->coll("inventory")->find( { item => undef } );
$cursor = $db->inventory->find(['item' => null]);
cursor = db.inventory.find({"item": None})
client[:inventory].find(item: nil)
var findObservable = collection.find(equal("item", BsonNull()))

The query returns both documents in the collection.查询返回集合中的两个文档。

Type Check类型检查

The { item : { $type: 10 } } query matches only documents that contain the item field whose value is null; i.e. the value of the item field is of BSON Type Null (type number 10) :｛item:｛$type:10｝｝查询仅匹配包含值为空的item字段的文档；即，项目字段的值为BSON类型Null（类型编号10）：

The { item : { $type: 10 } } query matches only documents that contain the item field whose value is null; i.e. the value of the item field is of BSON Type Null (type number 10) :{ item : { $type: 10 } }查询仅匹配包含值为null的item字段的文档；即，item字段的值为BSON类型Null（类型编号10）：

The Type("item", BsonType.Null) query using the FilterDefinitionBuilder.Type() method matches only documents that contain the item field whose value is null; i.e. the value of the item field is of BSON Type Null (type number 10) :

The following query matches only documents that contain the item field whose value is of BSON Type Null (type number 10) :以下查询仅匹配包含值为BSON类型Null（类型号10）的item字段的文档：

The type("item", BsonType.NULL) query matches only documents that contain the item field whose value is null; i.e. the value of the item field is of BSON Type Null (type number 10) :

The type("item", BsonType.NULL) query matches only documents that contain the item field whose value is null; i.e. the value of the item field is of BSON Type Null (type number 10) :

The type("item", BsonType.NULL) query matches only documents that contain the item field whose value is null; i.e. the value of the item field is of BSON Type Null (type number 10) :

The { item : { $type: 10 } } query matches only documents that contain the item field whose value is null; i.e. the value of the item field is of BSON Type Null (type number 10) :

The { item : { $type: 10 } } query matches only documents that contain the item field whose value is null; i.e. the value of the item field is of BSON Type Null (type number 10) :

The { item => { $type => 10 } } query matches only documents that contain the item field whose value is null; i.e. the value of the item field is of BSON Type Null (type number 10) :

The [ item => [ $type => 10 ] ] query matches only documents that contain the item field whose value is null; i.e. the value of the item field is of BSON Type Null (type number 10) :

The { item : { $type: 10 } } query matches only documents that contain the item field whose value is null; i.e. the value of the item field is of BSON Type Null (type number 10) :

The { item => { $type => 10 } } query matches only documents that contain the item field whose value is null; i.e. the value of the item field is of BSON Type Null (type number 10) :

db.inventory.find( { item : { $type: 10 } } )

Copy the following query filter document into the query bar and click Find:将以下查询筛选器文档复制到查询栏中，然后单击“查找”：

{ item : { $type: 10 } }
Find null type
var filter = Builders<BsonDocument>.Filter.Type("item", BsonType.Null);
var result = collection.Find(filter).ToList();
cursor, err := coll.Find(
	context.TODO(),
	bson.D{
		{"item", bson.D{
			{"$type", 10},
		}},
	})
findPublisher = collection.find(type("item", BsonType.NULL));
findIterable = collection.find(type("item", BsonType.NULL));
cursor = db.inventory.find({"item": {"$type": 10}})
const cursor = db.collection('inventory').find({
  item: { $type: 10 }
});
$cursor = $db->coll("inventory")->find( { item => { '$type' => 10 } } );
$cursor = $db->inventory->find(['item' => ['$type' => 10]]);
cursor = db.inventory.find({"item": {"$type": 10}})
client[:inventory].find(item: { '$type' => 10 })
findObservable = collection.find(bsonType("item", BsonType.NULL))

The query returns only the document where the item field has a value of null.查询仅返回item字段值为null的文档。

Existence Check存在性检查

The following example queries for documents that do not contain a field. 以下示例查询不包含字段的文档。[1]

The { item : { $exists: false } } query matches documents that do not contain the item field:{ item : { $exists: false } }查询与不包含item字段的文档匹配：

The { item : { $exists: false } } query matches documents that do not contain the item field:{ item : { $exists: false } }查询与不包含item字段的文档匹配：

The Exists("item", false) query using the FilterDefinitionBuilder.Exists() method matches documents that do not contain the item field:

The exists("item", false) query matches documents that do not contain the item field:

The exists("item", false) query matches documents that do not contain the item field:

The { item : { $exists: False } } query matches documents that do not contain the item field:

The { item : { $exists: false } } query matches documents that do not contain the item field:

The { item => { $exists => false } } query matches documents that do not contain the item field:

The [ item => [ $exists => false ] ] query matches documents that do not contain the item field:

The { item : { $exists: False } } query matches documents that do not contain the item field:

The { item => { $exists => false } } query matches documents that do not contain the item field:

The exists("item", exists = false) query matches documents that do not contain the item field:

db.inventory.find( { item : { $exists: false } } )

Copy the following query filter document into the query bar and click Find:将以下查询筛选器文档复制到查询栏中，然后单击“查找”：

{ item : { $exists: false } }
Query for null value
var filter = Builders<BsonDocument>.Filter.Exists("item", false);
var result = collection.Find(filter).ToList();
cursor, err := coll.Find(
	context.TODO(),
	bson.D{
		{"item", bson.D{
			{"$exists", false},
		}},
	})
findPublisher = collection.find(exists("item", false));
findIterable = collection.find(exists("item", false));
cursor = db.inventory.find({"item": {"$exists": False}})
const cursor = db.collection('inventory').find({
  item: { $exists: false }
});
# For boolean values, use boolean.pm for 'true' and 'false'
$cursor = $db->coll("inventory")->find( { item => { '$exists' => false } } );
$cursor = $db->inventory->find(['item' => ['$exists' => false]]);
cursor = db.inventory.find({"item": {"$exists": False}})
client[:inventory].find(item: { '$exists' => false })
findObservable = collection.find(exists("item", exists = false))

The query only returns the document that does not contain the item field.查询只返回不包含item字段的文档。

Tip提示

See also: 另请参见：

Reference documentation for the $type and $exists operators.$type和$exists运算符的参考文档。

[1] Starting in MongoDB 4.2, users can no longer use the query filter $type: 0 as a synonym for $exists:false. 从MongoDB 4.2开始，用户不能再使用查询筛选器$type:0作为$exists:false的同义词。To query for null or missing fields, see Query for Null or Missing Fields.要查询空字段或缺失字段，请参阅查询空字段和缺失字段。
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