Question

I have a page named “ReportController.aspx” whose purpose is to instantiate a report (class) based on query string parameters

        switch (Request.QueryString["Report"])
        {                
            case "ReportA":
                CreateReportAReport("ReportA's Title");
                break;
            case "ReportB":
                CreateReportBReport("ReportB's Title");
                break;                
            case "ReportC":
                CreateReportCReport("ReportC's Title");
                break;
            case "ReportD":
                CreateReportDReport("ReportD's Title");
                break;
                ...

Basically, each time a new report is needed there will be this overhead of adding a case and adding a method. This switch statement could get very very long. I read that is is possible to use a Dictionary to map a Report to ?. How would this look using a Dictionary (assuming this is a better way).

Also, CreateReportXReport method basically passes a bunch of additional QueryString values to the report class’s constructor (each report class has a different constructor).

Answer 1

Assuming that all reports implement IReport, you can do it using Func<IReport>, like this:

IDictionary<string,Func<IReport>> dictToReport = new Dictionary {
    {"ReportA", () => CreateReportAReport("ReportA's Title") }
,   {"ReportB", () => CreateReportBReport("ReportB's Title") }
,   ...
};

You can then replace the switch with this code:

var myReport = dictToReport[Request.QueryString["Report"]]();