从属性值获取属性

Question

具有这个简单的类：

public class Book
{
    [DataMember]
    [Column("Bok_Name")]
    [Author("AuthorName")]
    public string Name{ get; set; }

    [DataMember]
    [Column("Bok_Publisher")]
    public string Publisher{ get; set; }
}

我如何知道属性类型为Column且值为Bok_Name，如何从属性中获取PropertyInfo。 我试图用linq查询来做到这一点。

Answer 1

使用反射和.NET扩展名CustomAttributeExtensions.GetCustomAttribute {T}方法，可以找到具有自定义属性的属性。 在这种情况下，自定义属性来自System.ComponentModel.DataAnnotations.Schema.ColumnAttribute 。

var book = new Book { Name = "Jitterbug Perfume" };

PropertyInfo bokName = typeof(Book)
    .GetProperties(BindingFlags.Public | BindingFlags.Instance) // add other bindings if needed
    .FirstOrDefault(x => x.GetCustomAttribute<ColumnAttribute>() != null
       && x.GetCustomAttribute<ColumnAttribute>().Name.Equals("Bok_Name", StringComparison.OrdinalIgnoreCase));

// the above query only gets the first property with Column attribute equal to "Bok_Name"
// if there are more than one, then use a .Where clause instead of FirstOrDefault.
if (bokName != null)
{
    string name = bokName.GetValue(book).ToString();
    // do other stuff
}

Answer 2

    var type = typeof (Book); //or var type=instance.GetType();

    var res=type.GetProperties(BindingFlags.Instance | BindingFlags.Public | BindingFlags.NonPublic)
        .Where(
            p =>
                (p.GetCustomAttribute<ColumnAttribute>() ?? new ColumnAttribute()).Value == "Bok_Name");