asked on

Running a static method dynamically

I have saved my class names and method names in a database table. Based on the case type I pickup a class name, a method name from the database into respective strings and form an Argument String . How do I run this method dynamically? Please see sample code and suggest.

Thank You.
Normally if it weren't in the database I would run like this:

 ArgumentString = "/CaseNum " + caseNo + " /Ver " + StrVer + " /TemplateID " + TemplateID + " /ReportType " + ReportType;
Name189TFConsole.TF189(ArgumentString);

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With the strings coming in strings from the database I have the following code:

ArgumentString = "/CaseNum " + caseNo + " /Ver " + StrVer + " /TemplateID " + TemplateID + " /ReportType " + ReportType;
                string ClassName= "Name189TFConsole";
                string MethodName = "TF189";
//code to run the Method here.

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Thank You.

Todd Gerbert

Use Type.GetType to initialize a Type to the appropriate class, and Type.InvokeMember to execute a method.

using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Reflection;

class Program
{
	static void Main(string[] args)
	{
		string class1 = "TestClass1", method1 = "TestMethod", class2 = "TestClass2", method2 = "OtherTestMethod";

		Type type1 = Type.GetType(class1);
		type1.InvokeMember(method1, BindingFlags.InvokeMethod, null, type1, new object[] { });

		Type type2 = Type.GetType(class2);
		type2.InvokeMember(method2, BindingFlags.InvokeMethod, null, type2, new object[] { });

		Console.ReadKey();
	}
}

public class TestClass1
{
	public static void TestMethod()
	{
		Console.WriteLine("Hello World");
	}
}

public class TestClass2
{
	public static void OtherTestMethod()
	{
		Console.WriteLine("Other Method");
	}
}

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Daniel Van Der Werken

Here is one way to do it. It might not be the best or most efficient way, but it will work:

using System;
using System.Collections.Generic;
using System.Linq;
using System.Reflection;
using System.Reflection.Emit;
using System.Text;

namespace ConsoleApplication1
{
    class Program
    {
        static void Main( string[] args )
        {
            string className = "Name189TFConsole";
            string methodName = "TF189";

            Assembly thisAssembly = System.Reflection.Assembly.GetExecutingAssembly();
            Type[] thisTypes = thisAssembly.GetTypes();

            foreach ( Type t in thisTypes )
            {
                if ( string.Equals( t.Name, className, StringComparison.InvariantCultureIgnoreCase ) )
                {
                    MethodInfo[] methods = t.GetMethods();

                    foreach ( MethodInfo m in methods )
                    {
                        if ( string.Equals( m.Name, methodName, StringComparison.InvariantCultureIgnoreCase ) )
                        {
                            m.Invoke( null, null );
                        }
                    }
                }
            }
        }
    }

    public class Name189TFConsole
    {
        public Name189TFConsole() { }

        public static void TF189()
        {
            Console.WriteLine( "TF189" );
        }
    }
}

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Todd Gerbert

I suppose Dan7el raises a good point about checking the stuff actually exists. ;)

Type.GetType will get the type for you without needing to enumerate all the types in the assembly, and will ignore case. This example has a method to retrieve the corresponding MethodInfo from the Type (which is just about the same he has above), and then Invokes that MethodInfo.

using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Reflection;

class Program
{
	static void Main(string[] args)
	{
		string class1 = "testclass1", method1 = "testmethod", class2 = "testclass2", method2 = "othertestmethod";


		Type t1 = Type.GetType(class1, false, true);
		if (t1 == null)
			Console.WriteLine("Could not find type {0}.", class1);
		else
		{
			MethodInfo staticMethod = GetStaticMethod(t1, method1);
			if (staticMethod == null)
				Console.WriteLine("Could not find method {0}.", method1);
			else
				staticMethod.Invoke(t1, new object[] { });
		}

		Console.ReadKey();
	}

	static MethodInfo GetStaticMethod(Type t, string MethodName)
	{
		foreach (MethodInfo mi in t.GetMethods())
		{
			if (mi.Name.Equals(MethodName, StringComparison.InvariantCultureIgnoreCase) && mi.Attributes.HasFlag(MethodAttributes.Static))
				return mi;
		}

		return null;
	}
}

public class TestClass1
{
	public static void TestMethod()
	{
		Console.WriteLine("Hello World");
	}
}

public class TestClass2
{
	public static void OtherTestMethod()
	{
		Console.WriteLine("Other Method");
	}
}

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patd1

ASKER

Thanks for the solution. I tried the one suggested by tgerbert and I get the following compilation error:

'System.Reflection.MethodAttributes' does not contain a definition for 'HasFlag' and no extension method 'HasFlag' accepting a first argument of type 'System.Reflection.MethodAttributes' could be found (are you missing a using directive or an assembly reference?)

Any help is highly appreciated.

Thanks You

Todd Gerbert

HasFlag isn't available until .Net 4.0, you need to manually check the existence of a flag yourself otherwise. Bit-wise "AND" the Attributes with MethodAttributes.Whatever - if MethodAttributes.Whatever is set the result will be non-zero.

if (aVariable & SomeEnum.SomeFlag != 0)
  hasFlag = true
else
  hasFlag = false

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patd1

ASKER

Thanks again.
How do I pass parameters to the method?
And how would the invoke change if the method is not static?

example:
76MapToORU Object76 = new 76MapToORU();
Object76.Run(caseNo, Ver, TemplateID, Status);

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Todd Gerbert

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patd1

ASKER

I am getting this exception on line: Type t = Type.GetType(className, true, true);

base {System.SystemException} = {"Could not load type '76CGMapToORU ' from assembly 'Result_Generator_1, Version=1.0.0.0, Culture=neutral, PublicKeyToken=null'.":"76CGMapToORU "}

My current code:

 string className = "76CGMapToORU ";
 string methodName = "Run";
 Type t = Type.GetType(className, true, true); //I hv set throw on error to true to see the exception
....

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If I run the code below, it runs fine.

 76CGMapToORU 76CGMapToORUObject = new 76CGMapToORU ();
 76CGMapToORUObject .Run(caseNo, Ver, TemplateID, ReportType);

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Thanks for your help.

patd1

ASKER

please read as: string className = "76CGMapToORU";
There is no extra space there in the code, but I still get the exception.

patd1

ASKER

You can ignore the above messages. I appended the class name with namespace name and that worked.

Thanks for all your help.

Todd Gerbert

Type.GetType() assumes the current assembly. If 76CGMapToORU appears in a separate assembly, will need to supply a fully-qualified type name (e.g. ClassLibrary1.Class1, ClassLibrary1, Version=1.0.0.0, Culture=neutral, PublicKeyToken=null, or get a reference to that assembly and use Assembly.GetType().