C#, get property Display Name of DisplayAttribute, DataAnnotations, MemberExpression

DisplayName_For_Property.cs

using System;
using System.ComponentModel.DataAnnotations;
using System.Linq;
using System.Linq.Expressions;

/// <summary>
/// global type handling helper
/// </summary>
public static class GT<TModel>
{
    /// <summary>
    /// get DisplayAttribute Name of a property of Type
    /// </summary>
    public static string Display<TProperty>(Expression<Func<TModel, TProperty>> f)
    {
        var exp = f.Body as MemberExpression;
        var property = exp.Expression.Type.GetProperty(exp.Member.Name);
        var attr = property?.GetCustomAttributes(typeof(DisplayAttribute), false).FirstOrDefault() as DisplayAttribute;
        return attr?.GetName() ?? exp.Member.Name;
    }
}

/// <summary>
/// global type handling helper
/// </summary>
public static class GT
{
    /// <summary>
    /// get DisplayAttribute Name of a property of a model
    /// </summary>
    public static string Display<TProperty>(Expression<Func<TProperty>> f)
    {
        var exp = f.Body as MemberExpression;
        var property = exp.Expression.Type.GetProperty(exp.Member.Name);
        var attr = property?.GetCustomAttributes(typeof(DisplayAttribute), false).FirstOrDefault() as DisplayAttribute;
        return attr?.GetName() ?? exp.Member.Name;
    }
}

/// ===========================================
/// test case

class MyModel
{
    [Display(Name = "厚厚厚")]
    public decimal Foo { get; set; }

    public decimal Bar { get; set; }

}

class Program
{
    static void Main(string[] args)
    {
        string a1 = GT<MyModel>.Display(m => m.Foo);
        string a2 = GT<MyModel>.Display(m => m.Bar);

        MyModel model = new MyModel();
        string b1 = GT.Display(() => model.Foo);
        string b2 = GT.Display(() => model.Bar);

        Console.WriteLine($"{a1}, {a2}");
        Console.WriteLine($"{b1}, {b2}");
        Console.WriteLine("Press any key to continue.");
    }
}

//>>>>>>>>>>>>>>>>>>>>>>>
//>>> 厚厚厚, Bar
//>>> 厚厚厚, Bar
//>>> Press any key to continue.

Label.razor

///
/// 應用 @Utils.Display(For) 實作自訂 Label razor component.
/// 使用範例：<Label For="()=>model.FooProperty" />
/// 使用範例：<Label Title="欄位名稱" />
///

@using System
@using System.Linq
@using System.Linq.Expressions
@typeparam TProp    <--- generic type 泛型

@if (Title != null)
{
    <label>@Title</label>
}
else if (For != null)
{
    @* 自 Property 的 DisplayAttribute 屬性取 Title。 *@
    <label>@GT.Display(For)</label>
}
else
{
    <label></label>
}

@code{
    [Parameter] public Expression<Func<TProp>> For { get; set; }
    [Parameter] public string Title { get; set; }
}

p.displayName = p.name + " [from " + f.id + "]";