Calling a method by name with parameters (or build like sql)

.Net Version 4.5.1

Very Brief Background

I have a console application where the user enters a function and parameters. Rather than adding supported functions to a dictionary of some kind, I'd like to just have it call the method by name, using the method signature to validate the parameters. I can gather all the information I need in theory, but can't figure out how to CALL the expression.

I think I know why--it's because I can't figure out how to coerce my parameters into a form the Expression.Call line will accept. I tried using the ParameterExpression class, but it doesn't seem to contain the values, only the types and names.

What I Want to Do

///
/// Call a method in this class instance by name and parameters
///
///
///
///
public void Execute(string methodName, object[] args)
{
//get method we will be calling
MethodInfo method = GetMethodByName(methodName);
//validate & retrieve parameters based on the method signature
object[] parameters;
if (!GetAndValidateParams(
method.GetParameters().Select(pd => pd.ParameterType).ToArray(),
args,
out parameters))
return; //exit on failed validation of parameters
//call method using signature -- this is where I'm getting an error
Expression.Call(method, parameters);
}

I would also be happy with the ability to "assemble" a method call, like in this pseudocode:

MethodCall mc = new MethodCall(methodInfo);
mc.ClassInstance = this;
mc.Parameters.AddRange(parameters);
mc.Execute();

Thank you in advance for any help or guidance you can provide!

Daniel

Just in Case: The Validation Method

//validates that types are as expected. Only accepts string, int and decimal
private bool GetAndValidateParams(Type[] expected, object[] args, out object[] convertedArgs)
{
Console.Write("Validating parameters...");
//check for any unsupported types
convertedArgs = null;
Type[] supportedTypes = new Type[] { typeof(decimal), typeof(string), typeof(int) };
if (expected.Any(t => !supportedTypes.Any(st => t == st))) return false;
if (expected == null) return false;
if (expected.Count() == 0 && (args == null || args.Count() == 0))
{
Console.Write("Success.\r\n");
return true;
}
convertedArgs = new object[args.Count()];
for (int x = 0; x < expected.Count(); x++)
{
//check to make sure there are args left
if (x > (args.Count() - 1)) return false;
//if we have an arg and an expectation, check them
try { convertedArgs[x] = Convert.ChangeType(args[x], expected[x]); }
catch {return false;}
}
//If we got here, everything was validated successfully
Console.Write("Success.\r\n");
return true;
}

1 Reply

Know the answer? Post it — somebody with the same question will find it here.

Daniel Kaschel10y ago
Finally figured this out. I can't believe I sank so many hours into that. My final code:
public void Execute(string methodName, object[] args)
{
     //get called method
     MethodInfo mi = GetMethodByName(methodName);
     if (mi == null) return;


     //validate parameters
     var paramDefinitions = mi.GetParameters();
     object[] parameters;
     if (!ValidateParams(paramDefinitions.Select(pd => pd.ParameterType).ToArray(), args, out parameters))
         return;


     //execute
     try
     {
         mi.Invoke(this, parameters);
         return string.Empty;
     }
     catch { return; }
}