Find MVC template view by name

Question

I am writing an HtmlHelper extension and I need to search for the existence of a template by name. The template in question may be a display or editor template depending on the context. My initial thought was to use ViewEngines.Engines.FindPartialView method. However, it appears that this method is not searching the ~/Views/Shared/DisplayTemplates and ~/Views/Shared/EditorTemplates directories.
I suppose this is for good reason. After all, how would the ViewEngine know whether to return the display or editor template without some additional information of context?

So, that leads to the question: how can I search for a specific EditorTemplate/DisplayTemplate I've considered adding a custom view engine to the ViewEngines collection to include these locations. I'm concerned, however, that this might be problematic.

My main concern is that the DisplayTemplate/EditorTemplate view might be served up for something unintended. Does anyone else see this as a problem?
Is it a better idea just to new up a specific DisplayTemplateViewEngine/EditorTemplateViewEngine instance when necessary and keep the ViewEngines collection clear of this specific functionality?
Is there something else I'm missing?

Vinney Kelly · Accepted Answer · 2015-07-27 22:43:10Z

4

I absolutely love that the MVC framework is open source! I was able to determine, from the TemplateHelpers class (internal to the MVC Runtime) that the DataBoundControlMode is considered when rendering a template. The answer was simple! All I have to do is prefix the template name with the appropriate template director. So, to find a display template:

var metadata = ModelMetadata.FromLambdaExpression(expression, HtmlHelper.ViewData);
ViewEngines.Engines.FindPartialView(
    _controllerContext, 
    string.Format("DisplayTemplates/{0}", metadata.TemplateHint))

No additional view engines or routing required! In case you're interested in the application, my helper is auto-generating UI components for a given model. I wanted to enable the existence of a custom template to bypass the automated rendering.

edited Jul 27, 2015 at 22:43

answered May 2, 2013 at 15:05

Vinney Kelly

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3 Comments

Vinney Kelly Over a year ago

This is the answer. However I can't mark it as such for a couple of day. Sorry if you were attracted to this post because of it's apparent 'unanswered' status.

xr280xr Over a year ago

What is metadata.TemplateHint or where does it come from?

Vinney Kelly Over a year ago

@xr280xr: Updated to include metadata definition. Hope that serve you!

Community · Accepted Answer · 2017-05-23 12:21:43Z

0

A WebFormViewEngine has a few properties that define (patterns for) locations to search for views.

You either follow the convention of the view engine you use, or create a custom view engine (that for examlpe extends Razor) with custom view paths.

The latter is explained here:

public class CustomViewEngine : RazorViewEngine
{
    public CustomViewEngine()
    {
        var viewLocations =  new[] {  
            "~/Views/{1}/{0}.cshtml",  
            "~/Views/Shared/{0}.cshtml",  
            "~/Views/Shared/DisplayTemplates/{0}.cshtml",  
            "~/Views/Shared/DisplayTemplates/{1}/{0}.cshtml",
            // etc
        };

        this.PartialViewLocationFormats = viewLocations;
        this.ViewLocationFormats = viewLocations;
    }
}

So I guess in your helper you should look up the current view engine and look up its view location paths and search them in order. Doesn't an Html helper have a method or property for getting the view you're currently running in?

edited May 23, 2017 at 12:21

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answered May 2, 2013 at 14:43

CodeCaster

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5 Comments

Vinney Kelly Over a year ago

Thanks for the reply. I'm not actually breaking convention; my structure is withing the expected MVC architecture definitions. The issue is that the FindPartialView method of the ViewEnginesCollection doesn't search for those locations because it wouldn't know if you wanted to the display or editor version. I did find a solution, however. See my answer for reference. Thanks again.

Shimmy Weitzhandler Over a year ago

1) Is the code in your example the default Razor behavior? 2) What do {0} and {1} refer to?

CodeCaster Over a year ago

@Shimmy this is the default. The replacement values are {0} = view name, {1} = controller name and {2} = area name (see ViewLocation and AreaAwareViewLocation at the bottom of this file).

Shimmy Weitzhandler Over a year ago

So how do I use a view that's under another controller's view's EditorTemplates folder?

CodeCaster Over a year ago

@Shimmy ask a new question.

Jorge · Accepted Answer · 2013-05-02 14:54:40Z

0

Why you just map the relative path

string path = Server.MapPath("~/View/");

And then check if the file exits base on the .cshtml exit's in that specific directory

string fileName = "MyView.cshtml";
if (File.Exists(path + fileName))
    //do somethings
else
    //do another things

edited May 2, 2013 at 14:54

answered May 2, 2013 at 14:46

Jorge

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1 Comment

Vinney Kelly Over a year ago

One benefit of using the ViewEngine is that it can be mocked making it testable. This solution be really difficult to unit test. Glad for your input, though!

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