Question

i’ve got an action method like the following

public JsonResult Index(string version)
{
   .. do stuff, return some data v1 or v2. Default = v2.
}

So, this action method returns some data, which can be formatted either as Version 1 or Version 2 (whatever output that is … just know that they are schemantically different).

So, when a user wants to call access this resource, they the following :

http://www.blah.com/api/Index

nothing too hard.

they can also do this…

http://www.blah.com/api/Index?version=1.0

BUT, is it possible to make it so that the user can use the query string params version or v

eg. http://www.blah.com/api/Index?v=1.0 

and this will populate the version parameter in the ActionMethod. Possible?

Answer 1

I’m guessing you could manipulate the action method parameter(s) using an action filter.

Basically just check for a ‘v’ in the QueryString collection, and if it exists, throw it into the ActionParameters collection.

public override void OnActionExecuting(ActionExecutingContext filterContext)
{
    var version = filterContext.HttpContext.Request.QueryString["v"];
    if (!string.IsNullOrEmpty(version))
        filterContext.ActionParameters["version"] = version;
}

HTHs,
Charles

EDIT: Making it a bit more generic…

public class QueryStringToActionParamAttribute : ActionFilterAttribute
{
    private string _queryStringName;
    private string _actionParamName;

    public QueryStringToActionParamAttribute(string queryStringName, string actionParamName)
    {
        _queryStringName = queryStringName;
        _actionParamName = actionParamName;
    }

    public override void OnActionExecuting(ActionExecutedContext filterContext)
    {
        var queryStringValue = filterContext.HttpContext.Request.QueryString[_queryStringName];
        if (!string.IsNullOrEmpty(queryStringValue))
        {
            filterContext.ActionParameters[_actionParamName] = queryStringValue;
        }
    }
}

Then you could call it like:

[QueryStringToActionParam("v", "version")];