Method GroupBy
GroupBy<TSource, TKey>(IMongoQueryable<TSource>, Expression<Func<TSource, TKey>>)
Groups the elements of a sequence according to a specified key selector function.
public static IMongoQueryable<IGrouping<TKey, TSource>> GroupBy<TSource, TKey>(this IMongoQueryable<TSource> source, Expression<Func<TSource, TKey>> keySelector)Parameters
sourceIMongoQueryable<TSource>An IMongoQueryable<T> whose elements to group.
keySelectorExpression<Func<TSource, TKey>>A function to extract the key for each element.
Returns
- IMongoQueryable<IGrouping<TKey, TSource>>
An IMongoQueryable<T> that has a type argument of IGrouping<TKey, TElement> and where each IGrouping<TKey, TElement> object contains a sequence of objects and a key.
Type Parameters
TSourceThe type of the elements of
source.TKeyThe type of the key returned by the function represented in keySelector.
GroupBy<TSource, TKey, TResult>(IMongoQueryable<TSource>, Expression<Func<TSource, TKey>>, Expression<Func<TKey, IEnumerable<TSource>, 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.
public static IMongoQueryable<TResult> GroupBy<TSource, TKey, TResult>(this IMongoQueryable<TSource> source, Expression<Func<TSource, TKey>> keySelector, Expression<Func<TKey, IEnumerable<TSource>, TResult>> resultSelector)Parameters
sourceIMongoQueryable<TSource>An IMongoQueryable<T> whose elements to group.
keySelectorExpression<Func<TSource, TKey>>A function to extract the key for each element.
resultSelectorExpression<Func<TKey, IEnumerable<TSource>, TResult>>A function to create a result value from each group.
Returns
- IMongoQueryable<TResult>
An IMongoQueryable<T> that has a type argument of TResult and where each element represents a projection over a group and its key.
Type Parameters
TSourceThe type of the elements of
source.TKeyThe type of the key returned by the function represented in keySelector.
TResultThe type of the result value returned by resultSelector.