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IAggregateFluentExtensionsLookupTResult, TForeignDocument, TAsElement, TAs, TNewResult Method (IAggregateFluentTResult, IMongoCollectionTForeignDocument, BsonDocument, PipelineDefinitionTForeignDocument, TAsElement, ExpressionFuncTNewResult, TAs, AggregateLookupOptionsTForeignDocument, TNewResult)

Appends a lookup stage to the pipeline.

Namespace:  MongoDB.Driver
Assembly:  MongoDB.Driver (in MongoDB.Driver.dll) Version: 2.21.0+5a9c3311e158910b88195f290e6d4b1b2715d2b2
Syntax
public static IAggregateFluent<TNewResult> Lookup<TResult, TForeignDocument, TAsElement, TAs, TNewResult>(
	this IAggregateFluent<TResult> aggregate,
	IMongoCollection<TForeignDocument> foreignCollection,
	BsonDocument let,
	PipelineDefinition<TForeignDocument, TAsElement> lookupPipeline,
	Expression<Func<TNewResult, TAs>> as,
	AggregateLookupOptions<TForeignDocument, TNewResult> options = null
)
where TAs : Object, IEnumerable<TAsElement>

Parameters

aggregate
Type: MongoDB.DriverIAggregateFluentTResult
The aggregate.
foreignCollection
Type: MongoDB.DriverIMongoCollectionTForeignDocument
The foreign collection.
let
Type: MongoDB.BsonBsonDocument
The "let" definition.
lookupPipeline
Type: MongoDB.DriverPipelineDefinitionTForeignDocument, TAsElement
The lookup pipeline.
as
Type: System.Linq.ExpressionsExpressionFuncTNewResult, TAs
The as field in TNewResult in which to place the results of the lookup pipeline.
options (Optional)
Type: MongoDB.DriverAggregateLookupOptionsTForeignDocument, TNewResult
The options.

Type Parameters

TResult
The type of the result.
TForeignDocument
The type of the foreign collection documents.
TAsElement
The type of the as field elements.
TAs
The type of the as field.
TNewResult
The type of the new result.

Return Value

Type: IAggregateFluentTNewResult
The 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