# Queryable.First Method

## Definition

Returns the first element of a sequence.

## Overloads

First<TSource>(IQueryable<TSource>, Expression<Func<TSource,Boolean>>) |
Returns the first element of a sequence that satisfies a specified condition. |

First<TSource>(IQueryable<TSource>) |
Returns the first element of a sequence. |

## First<TSource>(IQueryable<TSource>, Expression<Func<TSource,Boolean>>)

Returns the first element of a sequence that satisfies a specified condition.

```
public:
generic <typename TSource>
[System::Runtime::CompilerServices::Extension]
static TSource First(System::Linq::IQueryable<TSource> ^ source, System::Linq::Expressions::Expression<Func<TSource, bool> ^> ^ predicate);
```

`public static TSource First<TSource> (this System.Linq.IQueryable<TSource> source, System.Linq.Expressions.Expression<Func<TSource,bool>> predicate);`

`static member First : System.Linq.IQueryable<'Source> * System.Linq.Expressions.Expression<Func<'Source, bool>> -> 'Source`

```
<Extension()>
Public Function First(Of TSource) (source As IQueryable(Of TSource), predicate As Expression(Of Func(Of TSource, Boolean))) As TSource
```

#### Type Parameters

- TSource

The type of the elements of `source`

.

#### Parameters

- source
- IQueryable<TSource>

An IQueryable<T> to return an element from.

- predicate
- Expression<Func<TSource,Boolean>>

A function to test each element for a condition.

#### Returns

- TSource

The first element in `source`

that passes the test in `predicate`

.

#### Exceptions

`source`

or `predicate`

is `null`

.

No element satisfies the condition in `predicate`

.

-or-

The source sequence is empty.

### Examples

The following code example demonstrates how to use First<TSource>(IQueryable<TSource>, Expression<Func<TSource,Boolean>>) to return the first element of a sequence that satisfies a condition.

```
int[] numbers = { 9, 34, 65, 92, 87, 435, 3, 54,
83, 23, 87, 435, 67, 12, 19 };
// Get the first number in the array that is greater than 80.
int first = numbers.AsQueryable().First(number => number > 80);
Console.WriteLine(first);
/*
This code produces the following output:
92
*/
```

```
Dim numbers() As Integer = {9, 34, 65, 92, 87, 435, 3, 54, _
83, 23, 87, 435, 67, 12, 19}
' Get the first number in the array that is greater than 80.
Dim first As Integer = numbers.AsQueryable().First(Function(number) number > 80)
MsgBox(first)
' This code produces the following output:
'
' 92
```

### Remarks

This method has at least one parameter of type Expression<TDelegate> whose type argument is one of the Func<T,TResult> types. For these parameters, you can pass in a lambda expression and it will be compiled to an Expression<TDelegate>.

The First<TSource>(IQueryable<TSource>, Expression<Func<TSource,Boolean>>) method generates a MethodCallExpression that represents calling First<TSource>(IQueryable<TSource>, Expression<Func<TSource,Boolean>>) itself as a constructed generic method. It then passes the MethodCallExpression to the Execute<TResult>(Expression) method of the IQueryProvider represented by the Provider property of the `source`

parameter.

The query behavior that occurs as a result of executing an expression tree that represents calling First<TSource>(IQueryable<TSource>, Expression<Func<TSource,Boolean>>) depends on the implementation of the type of the `source`

parameter. The expected behavior is that it returns the first element in `source`

that satisfies the condition specified by `predicate`

.

### Applies to

## First<TSource>(IQueryable<TSource>)

Returns the first element of a sequence.

```
public:
generic <typename TSource>
[System::Runtime::CompilerServices::Extension]
static TSource First(System::Linq::IQueryable<TSource> ^ source);
```

`public static TSource First<TSource> (this System.Linq.IQueryable<TSource> source);`

`static member First : System.Linq.IQueryable<'Source> -> 'Source`

```
<Extension()>
Public Function First(Of TSource) (source As IQueryable(Of TSource)) As TSource
```

#### Type Parameters

- TSource

The type of the elements of `source`

.

#### Parameters

- source
- IQueryable<TSource>

The IQueryable<T> to return the first element of.

#### Returns

- TSource

The first element in `source`

.

#### Exceptions

`source`

is `null`

.

The source sequence is empty.

### Examples

The following code example demonstrates how to use First<TSource>(IQueryable<TSource>) to return the first element in a sequence.

```
int[] numbers = { 9, 34, 65, 92, 87, 435, 3, 54,
83, 23, 87, 435, 67, 12, 19 };
int first = numbers.AsQueryable().First();
Console.WriteLine(first);
/*
This code produces the following output:
9
*/
```

```
Dim numbers() As Integer = {9, 34, 65, 92, 87, 435, 3, 54, _
83, 23, 87, 435, 67, 12, 19}
Dim first As Integer = numbers.AsQueryable().First()
MsgBox(first)
' This code produces the following output:
'
' 9
```

### Remarks

The First<TSource>(IQueryable<TSource>) method generates a MethodCallExpression that represents calling First<TSource>(IQueryable<TSource>) itself as a constructed generic method. It then passes the MethodCallExpression to the Execute<TResult>(Expression) method of the IQueryProvider represented by the Provider property of the `source`

parameter.

The query behavior that occurs as a result of executing an expression tree that represents calling First<TSource>(IQueryable<TSource>) depends on the implementation of the type of the `source`

parameter. The expected behavior is that it returns the first element in `source`

.