D365FOE. FormHasMethod extension for form extension methods.

Recently I have seen multiple people asking how to check if form has method added by extension at run-time.  For form methods we can use Global::formHasMethod but it does not work with form extensions. I advised people to use new metadata API to do this and finally community user Axaptus wrote the code!

I tweaked it a bit to ignore method’s name case as AX does and to exclude private methods. Also I used it to extend standard formHasMethod method. 

/// <summary>
/// The class <c>Global_Extension</c> contains extension methods for the <c>Global</c> class.
/// </summary>

[ExtensionOf(classStr(Global))]
public static final class Global_Extension
{
    static boolean formHasMethod(FormRun fr, IdentifierName methodName)
    {
        boolean ret = next formHasMethod(fr, methodName);

        if (!ret)
        {
            ret = Global::formExtensionHasMethod_IM(fr, methodName);
        }

        return ret;
    }

    private static boolean formExtensionHasMethod_IM(FormRun _formRun, IdentifierName _methodName)
    {
        if (!_formRun || !_methodName)
        {
            return false;
        }

        try
        {
            System.Object[] extensions = Microsoft.Dynamics.Ax.Xpp.ExtensionClassSupport::GetExtensionsOnType(_formRun.GetType(), true);

            if (extensions)
            {
                System.Type    formRunExtensionType;
                System.Reflection.MethodInfo    methodInfo;
                
                //extension methods are always static
                var  bindingFlags = BindingFlags::Public | BindingFlags::Static | BindingFlags::IgnoreCase;

                for (int i = 0; i < extensions.Length; i++)
                {
                    formRunExtensionType = extensions.GetValue(i);

                    var methodsInfo = formRunExtensionType.GetMethods(bindingFlags);

                    for (int n = 0; n < methodsInfo.get_Length(); n++)
                    {
                        methodInfo = methodsInfo.getValue(n);
                        if (methodInfo.Name == _methodName)
                        {
                            return true;
                        }
                    }
                }
            }
        }
        catch (Exception::CLRError)
        {
            error(CLRInterop::getLastException().ToString());
        }

        return false;
    }
}

Extending standard method has its pros and cons. From one side it will slow down execution of standard code that calls it when method does not exist, but it’s a rare case. From another side it allows you to reuse standard code without changing it and it could be handy in various places where AX looks for a method on a form.

Source code is available on GitHub