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IAggregateFluentExtensionsLookupTResult, TForeignDocument, TNewResult Method (IAggregateFluentTResult, IMongoCollectionTForeignDocument, ExpressionFuncTResult, Object, ExpressionFuncTForeignDocument, Object, ExpressionFuncTNewResult, Object, AggregateLookupOptionsTForeignDocument, TNewResult)
Appends a lookup stage to the pipeline.

Namespace: MongoDB.Driver
Assembly: MongoDB.Driver (in MongoDB.Driver.dll) Version: 2.2.0
Syntax
public static IAggregateFluent<TNewResult> Lookup<TResult, TForeignDocument, TNewResult>(
	this IAggregateFluent<TResult> aggregate,
	IMongoCollection<TForeignDocument> foreignCollection,
	Expression<Func<TResult, Object>> localField,
	Expression<Func<TForeignDocument, Object>> foreignField,
	Expression<Func<TNewResult, Object>> as,
	AggregateLookupOptions<TForeignDocument, TNewResult> options = null
)

Parameters

aggregate
Type: MongoDB.DriverIAggregateFluentTResult
The aggregate.
foreignCollection
Type: MongoDB.DriverIMongoCollectionTForeignDocument
The foreign collection.
localField
Type: System.Linq.ExpressionsExpressionFuncTResult, Object
The local field.
foreignField
Type: System.Linq.ExpressionsExpressionFuncTForeignDocument, Object
The foreign field.
as
Type: System.Linq.ExpressionsExpressionFuncTNewResult, Object
The field in the result to place the foreign matches.
options (Optional)
Type: MongoDB.DriverAggregateLookupOptionsTForeignDocument, TNewResult
The options.

Type Parameters

TResult
The type of the result.
TForeignDocument
The type of the foreign collection.
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