Possible to get Value from Attribute?

Question

I am using file helpers and I put on top of my class [DelimitedRecord("|")]

I want to check though if the value is a "|" if not then I want to throw an exception..

public void WriteResults<T>(IList<T> resultsToWrite, string path, string fileName) where T: class
        {      
            var attr =  (DelimitedRecordAttribute)Attribute.GetCustomAttribute(typeof(T), typeof(DelimitedRecordAttribute));

            if (attr.HasValue("|")) // has value does not exist.
            {
                FileHelperEngine<T> engine = new FileHelperEngine<T>();
                engine.HeaderText = String.Join("|", typeof(T).GetFields().Select(x => x.Name));

                string fullPath = String.Format(@"{0}\{1}-{2}.csv", path, fileName, DateTime.Now.ToString("yyyy-MM-dd"));

                engine.WriteFile(fullPath, resultsToWrite);
            }


        }

What can I use to check for that attribute is on the class with that value?

Edit

This is what I see as available properties

Answer 1

You can retrieve an instance of DelimitedRecordAttribute like this:

// t is an instance of the class decorated with your DelimitedRecordAttribute
DelimitedRecordAttribute myAttribute =
        (DelimitedRecordAttribute) 
        Attribute.GetCustomAttribute(t, typeof (DelimitedRecordAttribute));

If DelimitedRecordAttribute exposes a means of getting at the parameter (which it should), you can access the value via that means (typically a property), e.g. something like:

var delimiter = myAttribute.Delimiter

http://msdn.microsoft.com/en-us/library/71s1zwct.aspx

UPDATE

Since there doesn't seem to be a public property in your case, you can use reflection to enumerate the non-public fields and see if you can locate a field that holds the value, e.g. something like

FieldInfo[] fields = myType.GetFields(
                     BindingFlags.NonPublic | 
                     BindingFlags.Instance);

foreach (FieldInfo fi in fields)
{
    // Check if fi.GetValue() returns the value you are looking for
}

UPDATE 2

If this attribute is from filehelpers.sourceforge.net, the field you are after is

internal string Separator;

The full source code for that class is

[AttributeUsage(AttributeTargets.Class)]
public sealed class DelimitedRecordAttribute : TypedRecordAttribute
{
    internal string Separator;

/// <summary>Indicates that this class represents a delimited record. </summary>
    /// <param name="delimiter">The separator string used to split the fields of the record.</param>
    public DelimitedRecordAttribute(string delimiter)
    {
        if (Separator != String.Empty)
            this.Separator = delimiter;
        else
            throw new ArgumentException("sep debe ser <> \"\"");
    }


}

UPDATE 3

Get the Separator field like this:

FieldInfo sepField = myTypeA.GetField("Separator", 
                        BindingFlags.NonPublic | BindingFlags.Instance);

string separator = (string)sepField.GetValue();