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How to get a property that has a DataMemberAttribute with the specified name?

How can I reflect a property that has a DataMember with a given name (let each DataMember have a unique name)? For example, in the following code, a property with DataMember that has the name "p1" is PropertyOne:

[DataContract(Name = "MyContract")]
public class MyContract
{
    [DataMember(Name = "p1")]
    public string PropertyOne { get; set; }

    [DataMember(Name = "p2")]
    public string PropertyTwo { get; set; }

    [DataMember(Name = "p3")]
    public string PropertyThree { get; set; }
}

I currently have:

string dataMemberName = ...;

var dataMemberProperties = typeof(T).GetProperties().Where(p => p.GetCustomAttributes(typeof(DataMemberAttribute), false).Any());

var propInfo = dataMemberProperties.Where(p => ((DataMemberAttribute)p.GetCustomAttributes(typeof(DataMemberAttribute), false).First()).Name == dataMemberName).FirstOrDefault();

It works, but it seems that it can be improved. I especially don't like what GetCustomAttributes()gets called twice.

How can I rewrite it better? Ideally, it would be great if I could make it simple single-line.

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4 answers
// using System.Linq;
// using System.Reflection;
// using System.Runtime.Serialization;
obj.GetType()
   .GetProperties(…)
   .Where(p => Attribute.IsDefined(p, typeof(DataMemberAttribute)))
   .Single(p => ((DataMemberAttribute)Attribute.GetCustomAttribute(
                    p, typeof(DataMemberAttribute))).Name == "Foo");

Notes:

  • Attribute.IsDefined , , , Attribute.GetCustomAttribute .

  • Where , DataMemberAttribute: . Attribute.GetCustomAttribute Attribute.GetCustomAttributes.

+9

LINQ:

string dataMemberName = ...;
var propInfo =
    (from property in typeof(T).GetProperties()
    let attributes = property
        .GetCustomAttributes(typeof(DataMemberAttribute), false)
        .OfType<DataMemberAttribute>()
    where attributes.Any(a => a.Name == dataMemberName)
    select property).FirstOrDefault();

:

string dataMemberName = ...;
var propInfo = typeof(T)
    .GetProperties()
    .Where(p => p
        .GetCustomAttributes(typeof(DataMemberAttribute), false)
        .OfType<DataMemberAttribute>()
        .Any(x => x.Name == dataMemberName)
    )
    .FirstOrDefault();
+2

Fasterflect, :

var property = typeof(T).MembersAndAttributes( MemberTypes.Property, typeof(DataMemberAttribute) )
    .Where( ma => ma.Attributes.First().Name == dataMemberName )
    .Select( ma => ma.Member as PropertyInfo )
    .FirstOrDefault();

, - :

var property = typeof(T).PropertiesWith<DataMemberAttribute>( Flags.InstancePublic )
    .Where( p => p.Name == dataMemberName ).FirstOrDefault();

Fasterflect IL, .

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I needed to get the value of the property, not the property itself, which was used by Darin Dimitrov , but added .GetValue(this)to the end to return the value instead.

Here is what my class looked like:

[DataContract]
public class Item
{
    [DataMember(Name = "kpiId")]
    public string KPIId { get; set; }
    [DataMember(Name = "value")]
    public string Value { get; set; }
    [DataMember(Name = "unit")]
    public string Unit{ get; set; }
    [DataMember(Name = "status")]
    public string Status { get; set; }
    [DataMember(Name = "category")]
    public string Category { get; set; }
    [DataMember(Name = "description")]
    public string Description { get; set; }
    [DataMember(Name = "source")]
    public string Source { get; set; }
    [DataMember(Name = "messages")]
    public SysMessage[] Messages { get; set; }

    public object getDataMemberByName(string name)
    {
         return (typeof(Item).GetProperties().FirstOrDefault(p => p.GetCustomAttributes(typeof(DataMemberAttribute), false)
                              .OfType<DataMemberAttribute>()
                              .Any(x => x.Name == name))).GetValue(this);
    }
}
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