C# working with decorated members

Question

Take this class for example:

public class Applicant : UniClass<Applicant>
{
    [Key]
    public int Id { get; set; }

    [Field("X.838.APP.SSN")]
    public string SSN { get; set; }

    [Field("APP.SORT.LAST.NAME")]
    public string FirstName { get; set; }

    [Field("APP.SORT.FIRST.NAME")]
    public string LastName { get; set; }

    [Field("X.838.APP.MOST.RECENT.APPL")]
    public int MostRecentApplicationId { get; set; }
}

How would I go about getting all of the properties that are decorated with the field attribute, get their types, and then assign a value to them?

Answer 1

This is all done with reflection. Once you have a Type object, you can then get its PropertyInfo with myType.GetProperties(), from there, you can get each property's attributes with GetCustomAttributes(), and from there if you find your attribute, you've got a winner, and then you can proceed to work with it as you please.

You already have the PropertyInfo object, so you can assign to it with PropertyInfo.SetValue(object target, object value, object[] index)

Answer 2

You'll need to use Reflection:

var props =
   from prop in typeof(Applicant).GetProperties()
   select new {
      Property = prop,
      Attrs = prop.GetCustomAttributes(typeof(FieldAttribute), false).Cast<FieldAttribute>()
   } into propAndAttr
   where propAndAttr.Attrs.Any()
   select propAndAttr;

You can then iterate through this query to set the values:

foreach (var prop in props) {
   var propType = prop.Property.PropertyType;
   var valueToSet = GetAValueToSet(); // here's where you do whatever you need to do to determine the value that gets set
   prop.Property.SetValue(applicantInstance, valueToSet, null);
}

Answer 3

You would just need to invoke the appropriate reflection methods - try this:

<MyApplicationInstance>.GetType().GetProperties().Where(x => x.GetCustomAttributes().Where(y => (y as FieldAttribute) != null).Count() > 0);