C# - 如何在 Entity Framework Core 3.1 的模型中动态设置 builder.Property().HasComment

Question

我正在尝试将 builder.Property(_ => _.[DYNAMIC_FIELD_NAME]).HasComment("Some comment") 数据应用到具有 Description< 的所有属性 模型中的属性。到目前为止，这是我使用反射的尝试:

public class User : TableFieldsBase, IEntityTypeConfiguration<User>
{
    public void Configure(EntityTypeBuilder<User> builder)
    {
        var tableName = this.GetType().Name;
        builder.ToTable(tableName);
        
        var props = GetType().GetProperties();
        foreach(var prop in props)
        {
            var descriptionAttr = this.GetAttributeFrom<DescriptionAttribute>(prop.Name);
            if(descriptionAttr != null)
            {
                builder.Property(t => EF.Property<object>(t, prop.Name)).HasComment(descriptionAttr.Description);
            }
        }
    }

    [Description("This is the username")]
    public string Username { get; set; }
    
    [DisplayName("Email")]
    public string Email { get; set; }
}

正如您所看到的，我正在循环访问模型的所有属性并提取它们的描述文本。例如，用户名有一个描述属性，我想用它来将其保存在数据库的“评论”字段中。这里的问题是我不确定如何在 builder.Property 方法中动态应用该属性。也许我以错误的方式看待它？

这是我运行此代码时遇到的错误:

Exception has occurred: CLR/System.ArgumentException
Exception thrown: 'System.ArgumentException' in Microsoft.EntityFrameworkCore.dll: 'The expression 't => Property(t, value(Backend.Classes.Api.Avpf.Core.Models.User+<>c__DisplayClass0_0).prop.Name)' is not a valid property expression. The expression should represent a simple property access: 't => t.MyProperty'.'
   at Microsoft.EntityFrameworkCore.Infrastructure.ExpressionExtensions.GetPropertyAccess(LambdaExpression propertyAccessExpression)
   at Microsoft.EntityFrameworkCore.Metadata.Builders.EntityTypeBuilder`1.Property[TProperty](Expression`1 propertyExpression)
   at Backend.Classes.Api.Avpf.Core.Models.User.Configure(EntityTypeBuilder`1 builder) in Models\User.cs:line 38

提前致谢。

Answer 1

只需使用 Property使用 string propertyName 参数的方法重载:

builder.Property(prop.Name)
    .HasComment(descriptionAttr.Description);