Invoking a method via reflection using parameter names?

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Hi all,
I was just wondering if it would be possible to invoke a method via reflection if I have a set of

C#

KeyValuePair<string, object>

that describe the parameters and their values?

Point is that it seems that I might not always have the position of the parameter in the methods' signature, so it is impossible to create the parameter array for the method in the correct order.

Is it possible to invoke the method using parameter names?
Any help is kindly appreciated,

cheers and best regards
Andy

Posted 5-Jun-12 21:23pm

hoernchenmeister

Updated 5-Jun-12 21:24pm

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VJ Reddy · Accepted Answer · 2012-06-05T22:34:00

It is possible to Invoke a method using named parameters as explained here http://msdn.microsoft.com/en-us/library/system.reflection.bindingflags.aspx[^]

In one of the over loads of the Type.InvokeMember method we can pass an array of namedParameters as explained here http://msdn.microsoft.com/en-us/library/de3dhzwy[^]

The method of a class can be invoked using parameter names and values stored in a List of KeyValuePairs as shown below:

C#

Car car = new Car();
List<KeyValuePair<string,object>> paramData = new List<KeyValuePair<string,object>>();
//The order of parameters is given as parameter2, parameter1
paramData.Add(new KeyValuePair<string,object>("param2",50));
paramData.Add(new KeyValuePair<string,object>("param1","speed"));

car.GetType().InvokeMember("PrintData", BindingFlags.InvokeMethod, null, car,
    paramData.Select (d => d.Value).ToArray()
    ,null,null, paramData.Select (d => d.Key).ToArray());
//Output
//param1=speed and param2 = 50

List<KeyValuePair<string,object>> paramData2 = new List<KeyValuePair<string,object>>();
//The order of parameters is changed as parameter1, parameter2
paramData2.Add(new KeyValuePair<string,object>("param1","Speed---"));
paramData2.Add(new KeyValuePair<string,object>("param2",100));

car.GetType().InvokeMember("PrintData", BindingFlags.InvokeMethod, null, car,
    paramData2.Select (d => d.Value).ToArray()
    ,null,null, paramData2.Select (d => d.Key).ToArray());
//Output
//param1=Speed--- and param2 = 100

public class Car {
    public void PrintData(string param1, int param2){
        Console.WriteLine ("param1={0} and param2 = {1}",param1,param2);
    }
}

Manfred Rudolf Bihy · Accepted Answer · 2012-06-05T22:54:00

Yes this is possible. You will have to use the more elaborate method Type.InvokeMember[^].
The page describing the BindingFlags[^] parameter of the Type.InvokeMember method has a quite elaborate example with different usage scenarios. Search the page for this string: Invoking a method with named parameters which will take you to this part of the code:

C#

Console.WriteLine();
Console.WriteLine("Invoking a method with named parameters.");
Console.WriteLine("---------------------------------------");
// BindingFlags.InvokeMethod
// Call a method using named parameters.
object[] argValues = new object [] {"Mouse", "Micky"};
String [] argNames = new String [] {"lastName", "firstName"};
t.InvokeMember ("PrintName", BindingFlags.InvokeMethod, null, null, argValues, null, null, argNames);

Regards,

Manfred

Invoking a method via reflection using parameter names?

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