Calling C# method with parameters from data

问题:

Say, I have an XML String like this,

<METHOD>foo</METHOD>
<PARAM1>abc</PARAM1>
<PARAM2>def</PARAM2>
...
<PARAM99>ghi</PARAM99>
<PARAM100>jkl</PARAM100>

and I have a method

void foo(String param1, String param2, ..., String param99, String param100)
{
...
}

Is there any easy way for me to map this string to a real method call with the params matching the param names of the method in C#?

回答1:

Assuming you know the type, have an instance of it, and that the method is actually public:

string methodName = parent.Element("METHOD").Value;
MethodInfo method = type.GetMethod(methodName);

object[] arguments = (from p in method.GetParameters()
                      let arg = element.Element(p.Name)
                      where arg != null
                      select (object) arg.Value).ToArray();

// We ignore extra parameters in the XML, but we need all the right
// ones from the method
if (arguments.Length != method.GetParameters().Length)
{
    throw new ArgumentException("Parameters didn't match");
}

method.Invoke(instance, arguments);

Note that I'm doing case-sensitive name matching here, which wouldn't work with your sample. If you want to be case-insensitive it's slightly harder, but still doable - personally I'd advise you to make the XML match the method if at all possible.

(If it's non-public you need to provide some binding flags to the call to GetMethod.)

回答2:

How about something like this:

    public void Run(XmlElement rootElement)
    {
        Dictionary<string, string> xmlArgs = new Dictionary<string,string>(StringComparer.OrdinalIgnoreCase);
        foreach( XmlElement elem in rootElement )
            xmlArgs[elem.LocalName] = elem.InnerText;

        MethodInfo mi = this.GetType().GetMethod(xmlArgs["METHOD"]);

        List<object> args = new List<object>();
        foreach (ParameterInfo pi in mi.GetParameters())
            args.Add(xmlArgs[pi.Name]);

        mi.Invoke(this, args.ToArray());
    }

回答3:

edit If you have to match the names in the constructor. Just throw the constructor away, as it is not a list of name/values but just a list of required objecttypes, and names aren't necessary. Use properties to match between the xml element name and the field in the class.