c# - 动态构建选择子句linq

Question

class someClass
{ 
    public int Id { get; set; }
    public string Name{ get; set; }
    ...
    public string someProperty { get; set; }          
}

Expression<Func<someClass, object>> selector = null;
selector = k => new { k.Id ,k.Name };
var serult = myData.Select(selector);

// .Select(p=> new {p.Name , p.Id}) etc.

此示例代码有效 但是；

Expression<Func<someClass, ???>> createSelector(string[] fields)
{
    ...
    ....
    return ...
} 

Expression<Func<someClass, ???>> selector = createSelector({"Name","Id"});

这可能吗？ 此方法在运行时创建动态选择器

Answer 1

这可用于创建您需要的表达式。

    public static Expression<Func<T, TReturn>> CreateSelector<T, TReturn>(string fieldName)
        where T : class
        where TReturn : class
    {
        ParameterExpression p = Expression.Parameter(typeof(T), "t");
        Expression body = Expression.Property(p, fieldName);
        Expression conversion = Expression.Convert(body, typeof(object));
        return Expression.Lambda<Func<T, TReturn>>(conversion, new ParameterExpression[] { p });
    }