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MongoQueryableGroupByTSource, TKey, TResult Method (IMongoQueryableTSource, ExpressionFuncTSource, TKey, ExpressionFuncTKey, IEnumerableTSource, TResult)
Groups the elements of a sequence according to a specified key selector function and creates a result value from each group and its key.

Namespace: MongoDB.Driver.Linq
Assembly: MongoDB.Driver (in MongoDB.Driver.dll) Version: 2.2.0
public static IMongoQueryable<TResult> GroupBy<TSource, TKey, TResult>(
	this IMongoQueryable<TSource> source,
	Expression<Func<TSource, TKey>> keySelector,
	Expression<Func<TKey, IEnumerable<TSource>, TResult>> resultSelector


Type: MongoDB.Driver.LinqIMongoQueryableTSource
An IMongoQueryableT whose elements to group.
Type: System.Linq.ExpressionsExpressionFuncTSource, TKey
A function to extract the key for each element.
Type: System.Linq.ExpressionsExpressionFuncTKey, IEnumerableTSource, TResult
A function to create a result value from each group.

Type Parameters

The type of the elements of source.
The type of the key returned by the function represented in keySelector.
The type of the result value returned by resultSelector.

Return Value

Type: IMongoQueryableTResult
An IMongoQueryableT that has a type argument of TResult and where each element represents a projection over a group and its key.

Usage Note

In Visual Basic and C#, you can call this method as an instance method on any object of type IMongoQueryableTSource. 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