Queryable::Union<TSource> Method (IQueryable<TSource>, IEnumerable<TSource>, IEqualityComparer<TSource>)
Produces the set union of two sequences by using a specified IEqualityComparer<T>.
Namespace: System.Linq
Assembly: System.Core (in System.Core.dll)
Type Parameters
- TSource
The type of the elements of the input sequences.
Parameters
- source1
- Type: System.Linq::IQueryable<TSource>
A sequence whose distinct elements form the first set for the union operation.
- source2
- Type: System.Collections.Generic::IEnumerable<TSource>
A sequence whose distinct elements form the second set for the union operation.
- comparer
- Type: System.Collections.Generic::IEqualityComparer<TSource>
An IEqualityComparer<T> to compare values.
Return Value
Type: System.Linq::IQueryable<TSource>An IQueryable<T> that contains the elements from both input sequences, excluding duplicates.
Usage Note
In Visual Basic and C#, you can call this method as an instance method on any object of type IQueryable<TSource>. When you use instance method syntax to call this method, omit the first parameter.| Exception | Condition |
|---|---|
| ArgumentNullException | source1 or source2 is nullptr. |
The Union<TSource>(IQueryable<TSource>, IEnumerable<TSource>, IEqualityComparer<TSource>) method generates a MethodCallExpression that represents calling Union<TSource>(IQueryable<TSource>, IEnumerable<TSource>, IEqualityComparer<TSource>) 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 source1 parameter.
The query behavior that occurs as a result of executing an expression tree that represents calling Union<TSource>(IQueryable<TSource>, IEnumerable<TSource>, IEqualityComparer<TSource>) depends on the implementation of the type of the source1 parameter. The expected behavior is that the set union of the elements in source1 and source2 is returned. The comparer parameter is used to compare values.
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