如何从c＃中的Inner函数返回？

Question

I have a function that is a wrapper for an external REST web API. In my function, I am checking for the required parameters and if they're there, then I make the request and return the data. If a required parameter is missing, I log the name of the missing parameter and return status as failure.

I have extracted the logging the missing parameter part to a function as it will be called multiple times across the function. Here is my code as it stands:

public string WrapFunc(Dictionary<string, string> parameter)
{
    //Check for required params
    if (parameter.ContainsKey("Param1") && !string.IsNullOrEmpty(parameter["Param1"]))
    {
        objWebAPiRequest.Param1 = parameter["Param1"];
    }
    else
    {
        LogRequiredParameterError("Param1");
        response = "FAILURE";
        return response;
    }
}

private void LogRequiredParameterError(string parameterName)
{
    //Logging the missing parameter name to db
}

I'm looking for a way to encapsulate the returning of the response in the LogRequiredParameterError method or better still an elegant way of returning the failure message without repeating myself. Any suggestions?

Answer 1

Add the missing parameters to a list as you go along, then process them once (and set the response to "FAILURE" once) at the end of the method.

public string WrapFunc(Dictionary<string, string> parameter)
{
    var response = "SUCCESS";
    var missingParams = new List<string>();

    //Check for required params
    if (parameter.ContainsKey("Param1") && !string.IsNullOrEmpty(parameter["Param1"]))
    {
        objWebAPiRequest.Param1 = parameter["Param1"];
    }
    else
    {
        // Add the name of the missing param to a list
        missingParams.Add("Param1");
    }

    if (missingParams.Any())
    {
        // Log all the missing parameters and set response to "FAILURE"
        foreach (var p in missingParams)
            LogRequiredParameterError(p);

        response = "FAILURE";
    }

    return response;
}

private void LogRequiredParameterError(string parameterName)
{
    //Logging the missing parameter name to db
}

Answer 2

Well, it's just 2 lines to replace, but you could do something like this:

public string WrapFunc(Dictionary<string, string> parameter)
{
    //Check for required params
    bool hasAllParams = true;
    hasAllParams = CheckParam(parameter, "Param1") && hasAllParams;
    //hasAllParams = CheckParam(parameter, "Param2") && hasAllParams; etc.

    if (hasAllParams)
    {
        //proceed normally
        response = "SUCCESS"; //might be worth making it a const
    }
    else
    {
        response = "FAILURE";            
    }
    return response;
}

private bool CheckParam(Dictionary<string, string> parameters, string paramName)
{
    if (!parameters.ContainsKey(paramName) || string.IsNullOrEmpty(parameters[paramName]))
    {
        LogRequiredParameterError(paramName);
        return false;
    }
    return true;
}

Alternatively, you could write specific checking functions for other parameters if there are different conditions for them other than just not being empty.

And to answer your original question - no, there is no way to call a method and have it force a return in its caller.