Non-200 Error Handling Question

[jakedowns]

During development, replacing the whole body with any and all server errors is great.
For production, not so great.

Is there a way I could prevent the entire body from being replaced on a failed up.replace call?

So that I may print a simpler, user-friendly error message about the server error? instead of printing exactly what the XHR returned and blowing away the user's entire context / state?

I tried setting the failLayer to auto, page, popup and modal, so that i could just sweep the error under the rug so-to-speak, to give the user a chance to navigate away to something else...

but they all fail with:

[UP] Could not find failure target in current popup (tried ["body"])
--
[UP] Could not find failure target in current modal (tried ["body"])
--
[UP] Could not find failure target in response (tried [".overlay-error-container"])

which breaks JS execution beyond that point, so my .fail handler never gets a chance to display my simplified error message.

[jakedowns]

update: i've wrapped my up.replace call in a try/catch block, and that seems to suffice for now

let options = {
    transition: 'none',
    history: false, // don't update url by default
    //failTarget: '.overlay-error-container', //default 'body'
    //fallback: '.overlay-error-container'
    failLayer: 'invisible-layer' // <- SWEEP NON-200s under the rug
  };

  if(do_update_url){
    options.history = next_history_url;
    options.historyMethod = 'replace';
  }

  return new Promise((resolve, reject)=>{
    try {
      up.replace('#search-results-overlay .inner', load_url, options)
        .then(()=>{
          resolve(); // resolve outer
        })
        // normalize outer promise to native Promise .catch
        // instead of Jquery Deferred .fail
        .fail(()=>{
          reject(); // reject outer

           // SHOW FRIENDLY ERROR, JS FAILS TO REACH THIS BIT
          $('#search-results-overlay .note.error').show();
        })
        .always(()=>{
          this.overlay_fetching_results = false;
        });
    }catch(e){
      reject();

       // SHOW FRIENDLY ERROR, THIS WORKS!
      $('#search-results-overlay .note.error').show();
    }
  });

[jakedowns]

another update: i was mistaken... try/catch did work to show friendly error message, but failLayer: 'bogus-layer-name' breaks up.replace entirely. :<

tried setting up.dom.config.fallbacks = ['.overlay-error-container']; same error though.

• is there some way i can offload the contents of XHR.body -> into some hidden dom element on the current page?

• or just override/disable/prevent the default failTarget/failLayer behaviour entirely?

• maybe the proper unpoly way to solve this would be a server-side try/catch and just always returning 200s & server-rendered friendly error message, when, for example, my search server is overloaded, however I can't always guarantee control of the server response status code at server-application level, and there may still be extreme error examples where I'd still rather not blow away the entire page body due to a server hiccup

[triskweline]

Right now up.replace will always swap a page fragement into up-target, up-fail-target or the first matching selector from up.config.fallbacks.

You cannot prevent this with catch or promise rejection handlers. The rejection handler will be called after up-fail-target was replaced with a non-200 response.

In a future version there might be a way to customize the handling of error responses. Currently the server is expected to always deliver a controlled response.