Question

I’m subclassing RazorViewEngine and i’m trying to override FindView and I’m stumped by how you implement the cache using ViewLocationCache.

Can anyone give me an example?

Answer 1

I eventually got it.
Here is my whole implementation:

public override ViewEngineResult FindView(ControllerContext controllerContext, string viewName, string masterName, bool useCache)
    {
        //Implement defualt exceptions
        if(controllerContext == null)
            throw new ArgumentNullException("The controllerContext parameter is null");
        if(string.IsNullOrEmpty(viewName))
            throw new ArgumentException("The viewName parameter is null or empty.");

        //Check cache if specified
        if(useCache && this.ViewLocationCache != null){
            string cachedLocation = ViewLocationCache.GetViewLocation(controllerContext.HttpContext, generateCacheKey(controllerContext, viewName));
            if (!string.IsNullOrEmpty(cachedLocation))
                return new ViewEngineResult(CreateView(controllerContext, cachedLocation, masterName), this);
        }

        //Create arguments for location formatting
        string trimmedViewName = string.Empty;
        if (viewName.EndsWith(".cshtml"))
            trimmedViewName = viewName.Remove(viewName.Length - 7);
        else
            trimmedViewName = viewName;
        object[] args = new object[] { trimmedViewName, controllerContext.RouteData.GetRequiredString("controller"), controllerContext.RouteData.GetRequiredString("module") };

        //Attempt to locate file
        List<string> searchedLocations = new List<string>();
        foreach(string location in ViewLocationFormats){
            string formatedLocation = string.Format(location,args);
            searchedLocations.Add(formatedLocation);
            if (FileExists(controllerContext, formatedLocation))
            {
                //File has been found. Add to cache and return view
                if(this.ViewLocationCache != null)
                    ViewLocationCache.InsertViewLocation(controllerContext.HttpContext, generateCacheKey(controllerContext, viewName), formatedLocation);

                return new ViewEngineResult(CreateView(controllerContext, formatedLocation, masterName), this);
            }
        }

        //Couldnt find view, return searched locations
        return new ViewEngineResult(searchedLocations);
    }
    public string generateCacheKey(ControllerContext controllerContext, string viewName)
    {
        return string.Format("{0}|{1}", controllerContext.RouteData.GetRequiredString("module"), viewName);
    }