| IAggregateFluentExtensionsLookupTResult Method (IAggregateFluentTResult, IMongoCollectionBsonDocument, BsonDocument, PipelineDefinitionBsonDocument, BsonDocument, FieldDefinitionBsonDocument, IEnumerableBsonDocument) | 
 
            Appends a lookup stage to the pipeline.
            
 
    Namespace: 
   MongoDB.Driver
    Assembly:
   MongoDB.Driver (in MongoDB.Driver.dll) Version: 2.12.2+a4a3888f4fb51bb518b1eb5002effc2d47f2ea6a
 Syntax
Syntaxpublic static IAggregateFluent<BsonDocument> Lookup<TResult>(
	this IAggregateFluent<TResult> aggregate,
	IMongoCollection<BsonDocument> foreignCollection,
	BsonDocument let,
	PipelineDefinition<BsonDocument, BsonDocument> lookupPipeline,
	FieldDefinition<BsonDocument, IEnumerable<BsonDocument>> as
)
<ExtensionAttribute>
Public Shared Function Lookup(Of TResult) ( 
	aggregate As IAggregateFluent(Of TResult),
	foreignCollection As IMongoCollection(Of BsonDocument),
	let As BsonDocument,
	lookupPipeline As PipelineDefinition(Of BsonDocument, BsonDocument),
	as As FieldDefinition(Of BsonDocument, IEnumerable(Of BsonDocument))
) As IAggregateFluent(Of BsonDocument)
[<ExtensionAttribute>]
static member Lookup : 
        aggregate : IAggregateFluent<'TResult> * 
        foreignCollection : IMongoCollection<BsonDocument> * 
        let : BsonDocument * 
        lookupPipeline : PipelineDefinition<BsonDocument, BsonDocument> * 
        as : FieldDefinition<BsonDocument, IEnumerable<BsonDocument>> -> IAggregateFluent<BsonDocument> 
Parameters
- aggregate
- Type: MongoDB.DriverIAggregateFluentTResult
 The aggregate.
- foreignCollection
- Type: MongoDB.DriverIMongoCollectionBsonDocument
 The foreign collection.
- let
- Type: MongoDB.BsonBsonDocument
 The "let" definition.
- lookupPipeline
- Type: MongoDB.DriverPipelineDefinitionBsonDocument, BsonDocument
 The lookup pipeline.
- as
- Type: MongoDB.DriverFieldDefinitionBsonDocument, IEnumerableBsonDocument
 The as field in the result in which to place the results of the lookup pipeline.
Type Parameters
- TResult
- The type of the result.
Return Value
Type: 
IAggregateFluentBsonDocumentThe fluent aggregate interface.
Usage Note
In Visual Basic and C#, you can call this method as an instance method on any object of type 
IAggregateFluentTResult. When you use instance method syntax to call this method, omit the first parameter. For more information, see 
Extension Methods (Visual Basic) or 
Extension Methods (C# Programming Guide).
 See Also
See Also