Retrieve value from field attribute C#-CodePudding

I created some custom attribute to apply it on a class member:

    [
        System.AttributeUsage(
            AttributeTargets.Field | AttributeTargets.Property, AllowMultiple = true
        )
    ]
    internal class ActionAttribute : Attribute
    {
        private Action action;

        public ActionAttribute(Action action)
        {
            this.action = action;
        }

        public Action getThis()
        {
            return this.action;
        }

    }

But am struggling on how to retrieve it's value using reflection.

This is my attempt:

public static Device Serialize(string deviceName, Dictionary<string, dynamic> fields)
{
    var itce = devices[deviceName];
    Type objectType = itce.GetType();
    MemberInfo[] fieldsInfo = objectType.GetMembers();

    foreach (var field in fieldsInfo.Where(p => p.MemberType == MemberTypes.Property))
    {
        Console.WriteLine(field.Name);
        object[] actionAttributes = field.GetCustomAttributes(typeof(ActionAttribute), false);
        foreach (var cAttr in actionAttributes)
        {
            Console.WriteLine("Attrs: "   cAttr.GetType());
        }
    }
    return itce;
}

Where in the variable itce I just retrieve a previously allocated instance of a type that contains those attributes using a factory pattern.

The thing I want it's is actual value, but I only can read it's class definition full name. It's obvious, I am asking for it to the GetType() method, but I have only four opts available like ToString() and things like that. I am imagine that I am missing some type cast probably? Don't know. Hope someone could help me with this.

BTW, Action type it's just an enum:

enum Action
{
    Read,
    Write
}

and, a simple example of the usage of the attributes:

    public class Device : Display
    {
        [Action(Action.Read)]
        [Action(Action.Write)]
        public string device_name { get; set; }

        public Device(string device_name)
        {
            this.device_name = device_name;
        }
    }

So, the idea, it's to retrieve the value of the attribute whenever a type has a field annotated. Above, Device has two annotations, Read and Write. I want to recover with reflection the actual value or values attached to that field.

device_name has two attributes, so I need to recover Action.Read and Action.Write.

Thanks.

CodePudding user response：

As @freakish pointed, solution it's pretty straightfoward.

object[] actionAttributes = field.GetCustomAttributes(typeof(ActionAttribute), false);
foreach (var cAttr in actionAttributes)   
{
    var attr = (ActionAttribute)cAttr;   
    Console.WriteLine("Attrs: "   attr.getThis());
}

Casting the var cAttr to the attribute type allows me to easily access the info that holds the field attribute.

CodePudding user response：

Instead of using var for your loop control variable and it being object, specify the type as your attribute:

object[] actionAttributes = field.GetCustomAttributes(typeof(ActionAttribute), false);
foreach (ActionAttribute cAttr in actionAttributes)
{
    Console.WriteLine("Attrs: "   cAttr.getThis());
}

Of course, you really ought to be using a public read-only property, rather than a private field and a method, to access that value.