PipelineDefinitionBuilder.Lookup<TInput, TIntermediate, TForeignDocument, TOutput> Method (PipelineDefinition<TInput, TIntermediate>, IMongoCollection<TForeignDocument>, FieldDefinition<TIntermediate>, FieldDefinition<TForeignDocument>, FieldDefinition<TOutput>, AggregateLookupOptions<TForeignDocument, TOutput>)

Appends a $lookup stage to the pipeline.

Namespace: MongoDB.Driver
Assembly: MongoDB.Driver (in MongoDB.Driver.dll) Version: 2.21.0+5a9c3311e158910b88195f290e6d4b1b2715d2b2

Syntax

Copy

public static PipelineDefinition<TInput, TOutput> Lookup<TInput, TIntermediate, TForeignDocument, TOutput>(
	this PipelineDefinition<TInput, TIntermediate> pipeline,
	IMongoCollection<TForeignDocument> foreignCollection,
	FieldDefinition<TIntermediate> localField,
	FieldDefinition<TForeignDocument> foreignField,
	FieldDefinition<TOutput> as,
	AggregateLookupOptions<TForeignDocument, TOutput> options = null
)

<ExtensionAttribute>
Public Shared Function Lookup(Of TInput, TIntermediate, TForeignDocument, TOutput) ( 
	pipeline As PipelineDefinition(Of TInput, TIntermediate),
	foreignCollection As IMongoCollection(Of TForeignDocument),
	localField As FieldDefinition(Of TIntermediate),
	foreignField As FieldDefinition(Of TForeignDocument),
	as As FieldDefinition(Of TOutput),
	Optional options As AggregateLookupOptions(Of TForeignDocument, TOutput) = Nothing
) As PipelineDefinition(Of TInput, TOutput)

[<ExtensionAttribute>]
static member Lookup : 
        pipeline : PipelineDefinition<'TInput, 'TIntermediate> * 
        foreignCollection : IMongoCollection<'TForeignDocument> * 
        localField : FieldDefinition<'TIntermediate> * 
        foreignField : FieldDefinition<'TForeignDocument> * 
        as : FieldDefinition<'TOutput> * 
        ?options : AggregateLookupOptions<'TForeignDocument, 'TOutput> 
(* Defaults:
        let _options = defaultArg options null
*)
-> PipelineDefinition<'TInput, 'TOutput>

Parameters

pipeline: Type: MongoDB.Driver.PipelineDefinition<TInput, TIntermediate>
The pipeline.
foreignCollection: Type: MongoDB.Driver.IMongoCollection<TForeignDocument>
The foreign collection.
localField: Type: MongoDB.Driver.FieldDefinition<TIntermediate>
The local field.
foreignField: Type: MongoDB.Driver.FieldDefinition<TForeignDocument>
The foreign field.
as: Type: MongoDB.Driver.FieldDefinition<TOutput>
The "as" field.
options (Optional): Type: MongoDB.Driver.AggregateLookupOptions<TForeignDocument, TOutput>
The options.

Type Parameters

TInput: The type of the input documents.
TIntermediate: The type of the intermediate documents.
TForeignDocument: The type of the foreign collection documents.
TOutput: The type of the output documents.

Return Value

Type: PipelineDefinition<TInput, TOutput>
A new pipeline with an additional stage.

Usage Note

In Visual Basic and C#, you can call this method as an instance method on any object of type PipelineDefinition<TInput, TIntermediate>. 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).

Reference

PipelineDefinitionBuilder Class

Lookup Overload

MongoDB.Driver Namespace