c# - 表达式树 linq 获取参数的值？

Question

AddOptional<tblObject>(x =>x.Title, objectToSend.SupplementaryData);

private static void AddOptional<TType>(Expression<Func<TType,string>> expr, Dictionary<string, string> dictionary)
{
    string propertyName;
    string propertyValue;

    Expression expression = (Expression)expr;
    while (expression.NodeType == ExpressionType.Lambda)
    {
        expression = ((LambdaExpression)expression).Body;
    }
}

在上面的代码中，我想获得属性标题的实际值，而不仅仅是属性名称，这可能吗？

Answer 1

private static void Main(string[] args)
{
    CompileAndGetValue<tblObject>(x => x.Title, new tblObject() { Title =  "test" });
}

private static void CompileAndGetValue<TType>(
    Expression<Func<TType, string>> expr,
    TType obj)
{
    // you can still get name here

    Func<TType, string> func = expr.Compile();
    string propretyValue = func(obj);
    Console.WriteLine(propretyValue);
}

但是，您必须意识到这可能会很慢。您应该衡量它在您的情况下的表现。

如果您不喜欢传递您的对象：

    private static void Main(string[] args)
    {
        var yourObject = new tblObject {Title = "test"};
        CompileAndGetValue(() => yourObject.Title);
    }


    private static void CompileAndGetValue(
        Expression<Func<string>> expr)
    {
        // you can still get name here

        var func = expr.Compile();
        string propretyValue = func();
        Console.WriteLine(propretyValue);
    }