Expression.Field Método

Origem:

MemberExpression.cs

Origem:

MemberExpression.cs

Origem:

MemberExpression.cs

public:
 static System::Linq::Expressions::MemberExpression ^ Field(System::Linq::Expressions::Expression ^ expression, System::Reflection::FieldInfo ^ field);

public static System.Linq.Expressions.MemberExpression Field (System.Linq.Expressions.Expression expression, System.Reflection.FieldInfo field);

public static System.Linq.Expressions.MemberExpression Field (System.Linq.Expressions.Expression? expression, System.Reflection.FieldInfo field);

static member Field : System.Linq.Expressions.Expression * System.Reflection.FieldInfo -> System.Linq.Expressions.MemberExpression

Public Shared Function Field (expression As Expression, field As FieldInfo) As MemberExpression

Parâmetros

Retornos

Um MemberExpression que tem a propriedade NodeType igual a MemberAccess e as propriedades Expression e Member definidas com os valores especificados.

Exceções

Comentários

A Type propriedade do resultante MemberExpression é igual à FieldType propriedade de field.

Origem:

MemberExpression.cs

Origem:

MemberExpression.cs

Origem:

MemberExpression.cs

public:
 static System::Linq::Expressions::MemberExpression ^ Field(System::Linq::Expressions::Expression ^ expression, System::String ^ fieldName);

public static System.Linq.Expressions.MemberExpression Field (System.Linq.Expressions.Expression expression, string fieldName);

static member Field : System.Linq.Expressions.Expression * string -> System.Linq.Expressions.MemberExpression

Public Shared Function Field (expression As Expression, fieldName As String) As MemberExpression

Parâmetros

Retornos

Um MemberExpression que tem a propriedade NodeType igual a MemberAccess, a propriedade Expression definida como expression e a propriedade Member definida como o FieldInfo que representa o campo indicado por fieldName.

Exceções

Exemplos

O exemplo de código a seguir mostra como criar uma expressão que representa o acesso a um campo.

// Add the following directive to your file:
// using System.Linq.Expressions;

class TestFieldClass
{
    int sample = 40;
}

static void TestField()
{
    TestFieldClass obj = new TestFieldClass();

    // This expression represents accessing a field.
    // For static fields, the first parameter must be null.
    Expression fieldExpr = Expression.Field(
        Expression.Constant(obj),
        "sample"
    );

    // The following statement first creates an expression tree,
    // then compiles it, and then runs it.
    Console.WriteLine(Expression.Lambda<Func<int>>(fieldExpr).Compile()());
}

// This code example produces the following output:
//
// 40

' Add the following directive to your file:
' Imports System.Linq.Expressions

Class TestFieldClass
    Dim sample As Integer = 40
End Class

Sub TestField()

    Dim obj As New TestFieldClass()

    ' This expression represents accessing a field.
    ' For static fields, the first parameter must be Nothing.
    Dim fieldExpr As Expression = Expression.Field(
          Expression.Constant(obj),
          "sample"
      )

    ' The following statement first creates an expression tree,
    ' then compiles it, and then runs it.
    Console.WriteLine(Expression.Lambda(Of Func(Of Integer))(fieldExpr).Compile()())
End Sub

' This code example produces the following output:
'
' 40

Comentários

A Type propriedade do resultante MemberExpression é igual à FieldType propriedade do FieldInfo que representa o campo indicado por fieldName.

Esse método pesquisa expression. Digite e seus tipos base para um campo que tem o nome fieldName. Os campos públicos recebem preferência sobre campos não públicos. Se um campo correspondente for encontrado, esse método passará expression e o FieldInfo que representa esse campo para Field.

Origem:

MemberExpression.cs

Origem:

MemberExpression.cs

Origem:

MemberExpression.cs

public:
 static System::Linq::Expressions::MemberExpression ^ Field(System::Linq::Expressions::Expression ^ expression, Type ^ type, System::String ^ fieldName);

public static System.Linq.Expressions.MemberExpression Field (System.Linq.Expressions.Expression expression, Type type, string fieldName);

public static System.Linq.Expressions.MemberExpression Field (System.Linq.Expressions.Expression? expression, Type type, string fieldName);

static member Field : System.Linq.Expressions.Expression * Type * string -> System.Linq.Expressions.MemberExpression

Public Shared Function Field (expression As Expression, type As Type, fieldName As String) As MemberExpression

Parâmetros

Retornos

O MemberExpression criado.