Extension method: TResult FirstOrDefault<TSource, TResult>(this IQueryable<TSource>, Expression<Func<TSource, bool>>, Func<TSource, TResult>, TResult)

• Declared in: RT.Util.ExtensionMethods.IQueryableExtensions

Declaration

public static TResult FirstOrDefault<TSource, TResult>(
    this IQueryable<TSource> source,
    Expression<Func<TSource, bool>> predicate,
    Func<TSource, TResult> resultSelector,
    TResult default
)

Summary

Returns the first element of a sequence, or a default value if the sequence contains no elements.

Generic type parameters

TSource	The type of the elements of source.
TResult	The type of the resulting value.

Parameters

this IQueryable<TSource>	source	The collection to return the first element of.
Expression<Func<TSource, bool>>	predicate	A function to test each element for a condition.
Func<TSource, TResult>	resultSelector	A function to transform the first element into the result value. Will only be called if the sequence contains an element that passes the test specified by predicate.
TResult	default	The default value to return if the sequence contains no elements.

Returns

default if source is empty or if no element passes the test specified by predicate; otherwise, the transformed first element in source that passes the test specified by predicate.