Question

我有以下C＃代码，它从lambda表达式中获取成员名称：

public static class ObjectInformation<T>
{
    public static string GetPropertyName<TProp>(Expression<Func<T, TProp>> propertyLambda)
    {
        var memberExpression = propertyLambda.Body as MemberExpression;
        if (memberExpression == null)
        {
            throw new ArgumentException("Lambda must return a property.");
        }

        return memberExpression.Member.Name;
    }
}

public static class ObjectInformation
{
   public static string GetPropertyName<T>(Expression<Func<T>> propertyLambda)
    {
        var memberExpression = propertyLambda.Body as MemberExpression;
        if (memberExpression == null)
        {
            throw new ArgumentException("Lambda must return a property.");    
        }

        return memberExpression.Member.Name;
    }
}

我打电话给这样的方法：

ObjectInformation<RemoteCollectionContentViewModel>.GetPropertyName(e => e.SomeProperty);
ObjectInformation.GetPropertyName(() => SomeProperty)

我希望第二种方法使用第一种方法（不要复制代码），因此我需要将Func<T>转换为Func<T, TProp>。我怎么能做到这一点？

Answer 1

没有简单的方法来转换表达式类型。您将不得不重建整个表达式树。这不值得麻烦。有一种很好的旧方法来提取通用逻辑：

public static class ObjectInformation
{
    public static string GetPropertyName<T, TProp> (Expression<Func<T, TProp>> propertyLambda)
    {
        return GetPropertyName((LambdaExpression)propertyLambda);
    }

    public static string GetPropertyName<T> (Expression<Func<T>> propertyLambda)
    {
        return GetPropertyName((LambdaExpression)propertyLambda);
    }

    private static string GetPropertyName (LambdaExpression propertyLambda)
    {
        var memberExpression = propertyLambda.Body as MemberExpression;
        if (memberExpression == null)
            throw new ArgumentException("Lambda must return a property.");
        return memberExpression.Member.Name;
    }
}

转换表达式<func <t1>＆gt;表达式<func <t1，t2 =“”>＆gt; </func <t1，> </func <t1>

1 个答案: