Queryable.DefaultIfEmpty<'TSource> Method (IQueryable<'TSource>)
Returns the elements of the specified sequence or the type parameter's default value in a singleton collection if the sequence is empty.
Assembly: System.Core (in System.Core.dll)
static member DefaultIfEmpty<'TSource> : source:IQueryable<'TSource> -> IQueryable<'TSource>
Return ValueType: System.Linq.IQueryable<'TSource>
An IQueryable<'T> that contains default(TSource) if source is empty; otherwise, source.
The type of the elements of source.
The MethodCallExpression that represents calling itself as a constructed generic method. It then passes the MethodCallExpression to the CreateQuery<'TElement>(Expression) method of the IQueryProvider represented by the Provider property of the source parameter.method generates a
The query behavior that occurs as a result of executing an expression tree that represents calling IQueryable<'T> that contains default(TSource).depends on the implementation of the type of the source parameter. The expected behavior is that it returns source if it is not empty. Otherwise, it returns an
Available since 8
Available since 3.5
Portable Class Library
Supported in: portable .NET platforms
Available since 2.0
Windows Phone Silverlight
Available since 7.1
Available since 8.1