Reading from attribute in .NET

Question

In all of the tutorials out there for custom attributes they teach us how to create and define custom attributes which is no more than simple comment about the class/method. I am trying to figure out how can I read from those custom attributes in .NET inside some method. For example:

[SomeCustomAttr(param1, param2)]
public void Method1()
{
   read param1 from here
   read param2 from here
}

There are really great frameworks out there which do work with the entered data. Does anyone can give me some direction how to deal with this problem ?

Note that `param1` and `param2` are just parameters to the `SomeCustomAttr` constructor. Assuming that your ctor assigns those values to properties, you would just follow the information from that question, and access the two properties after getting the attribute object. — Jonathon Reinhart, Dec 09 '13 at 08:45

score 4 · Accepted Answer · answered Dec 09 '13 at 08:53

Assuming that the parameters you refer to are properties of the custom attribute class:

class Program
{
    static void Main(string[] args) {
        Test();
        Console.Read();
    }

    [Custom(Foo = "yup", Bar = 42)]
    static void Test() {
        // Get the MethodBase for this method
        var thismethod = MethodBase.GetCurrentMethod();

        // Get all of the attributes that derive from CustomAttribute
        var attrs = thismethod.GetCustomAttributes(typeof(CustomAttribute), true);

        // Assume that there is just one of these attributes
        var attr1 = (CustomAttribute)attrs.Single();

        // Print the two properties of the attribute
        Console.WriteLine("Foo = {0},  Bar = {1}", attr1.Foo, attr1.Bar);
    }
}

class CustomAttribute : Attribute
{
    public string Foo { get; set; }
    public int Bar { get; set; }
}

Note that attributes are a little special, in that they can take named parameters (which correspond to public property names), without declaring any constructor.

score 0 · Answer 2 · answered Dec 09 '13 at 09:11

0

Reflection is the right way to get the attribute.

            var TypeObj = typeof(Type1);
            var MethodInfoObj = TypeObj.GetMethod("Method1");

           // var AllAttributes= MethodInfoObj.GetCustomAttributes(true);

            var Attributes = MethodInfoObj.GetCustomAttributes(typeof(SomeCustomAttr), true);
            if (Attributes.Length > 0)
            {
                var AttributeObj = Attributes[0] as SomeCustomAttr;
                var value_param1  = AttributeObj.param1 ;
            }

answered Dec 09 '13 at 09:11

Priyank

1,353
9
13

1

A few pieces of advice: 1) Don't use `UpperCamelCase` for variable names (e.g. `TypeObj`) - C# convention uses that for class names. 2) If you use `as`, you should really check for `null`. 3) I'm sure this was a snippet from somewhere, but it'd still be nice if you indented it properly, to make it easier to read. – Jonathon Reinhart Dec 10 '13 at 00:54

Reading from attribute in .NET

2 Answers2