RedirectToAction: add fragment support

[Bartmax]

I can't find a way to use RedirectToAction using a fragment.

I tried:

 RedirectToAction(nameof(Index), new { fragment= "contact-message" });

with no success, looking at source code I couldn't identity if this feature exists or not.

This works, but is kind of verbose:

var localUrl = Url.Action(nameof(Index), controller: null, values: null, protocol: null, host: null, fragment: "contact-message");
return new LocalRedirectResult(localUrl);

[Eilon]

@Bartmax yup that's pretty much the way to do it. Certainly back in the day sending a fragment never made sense in a redirect because that's a server concept, and fragments are a client concept.

Is the scenario here that you want to send the fragment to a client library to later process something?

[Bartmax]

I'm using it in a simplier scenario (non client-side). So, I don't agree with the never makes sense ;)

I have a contact us form, after filling all fields and posting a welcome message appears "thanks for contacting us" on the same page.
This is done via client side, but as good practice I always fallback to server behavior. The form is in the middle of the page and the "thanks message" appears where the form was before the post. Without the fragment the message would be off-screen on lots of devices. I use the fragment to make the browser scroll to the desired position. Redirect is because I'm using PRG pattern.

Is more like "plain-old" html use case here.

I'm not sure if I was describing the scenario clear enough. Let me know if that helps.

[Eilon]

@Bartmax thanks that makes sense.

[rynowak]

This would be easy to add. UrlActionContext and UrlHelper already have the plumbing to process it.

[vincez]

+1

[juunas11]

What if the action being redirected to has a parameter called fragment? If we take fragment from the route values and make it the fragment, wouldn't it essentially block this scenario:

public IActionResult MyAction(string fragment){}

[Eilon]

@juunas11 that's right, so we probably wouldn't use a special fragment token like that, but instead add an explicit parameter.

[Eilon]

@dougbu assigning this bug to you because I assigned the associated PR to you as well.

[dougbu]

1dd1d49

[dougbu]

Thanks very much @juunas11 !

[Bartmax]

woot! amazing, thanks @juunas11 !