Add status code and error messages to data

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Right now Frontity doesn’t return proper status codes for 4xx and 5xx REST API errors. All REST API errors become a 404, which is wrong.

The first step to solve this is to populate data with the correct information from the REST API, so the Frontity app can make decisions based on that info.

User Stories

As a Frontity developer
I want to know about status codes and errors from the REST API
so that I can make decisions of what to show in the front-end

Possible solution

If there is an error in actions.source.fetch we have to populate the data object with info about that error.

  • REST API errors: When we catch the error, we use that info to populate data.

In order to catch the fetch errors, you need to see if the response was ok and if not, throw the response as the error object:

const response = await fetch("")
if (!response.ok) { throw response }

Then we add this to data:[route] = {
        is404: true, // The status code converted to is.
        errorStatus: 404, // status
        errorStatusText: "Not found" // statusText
        isError: true // always true for errors
        isFetching: false,
        isReady: true

Also, isReady must be true because we already have information about that URL which is the true meaning of isReady.

  • JavaScript errors: we throw the error again and let the developer deal with it.

I guess you’re going to find out that sometimes you have to throw the response error message (with status and statusText) yourself, like in this case:


For the react component handling the error logic in the twentytwenty and mars themes, do you have some particular idea in mind?

I think that we are not supposed to show a separate error page .e.g. if there is a 500 error.

I think that we could catch the error and show a “toast notification” or a dismissible dialog. Is that what you had in mind?

My idea was to show a general “Something went wrong” screen. With this type of routing:

        {(data.isFetching && <Loading />) ||
          (data.isArchive && <List />) ||
          (data.isPostType && <Post />) ||
          (data.is404 && <Page404 />) ||
          (data.isError && <ErrorPage />}

Maybe we can reuse ErrorPage for both errors:

        {(data.isFetching && <Loading />) ||
          (data.isArchive && <List />) ||
          (data.isPostType && <Post />) ||
          (data.isError && <ErrorPage />)

and change the message if it is a 404:

const ErrorPage = ({ state }) => {
  const data = state.source.get(;
  if (data.is404) return <div>Ops, that page can't be found.</div>;
  return <div>Ops! Something went wrong.</div>;

The theme needs to inform the user if either the page doesn’t exist or something else happened.

Of course this is only to show people how it works, they can implement it however they want.

1 Like

Why do you think that?

I think that in the context of a client-side web application it’s a better user experience if we allow the user to stay on the current page if there is a problem with fetching data for the next page, rather than redirect to an “Error Page”.

So, for example:

  1. User is on the archive page.
  2. Clicks on the link to a post The Beauties of Gullfoss
  3. The data fails to load
  4. a) we redirect the user to an error page
    b) we show a toast notification saying something went wrong and the user stays on the archive page.

I think b) is better :slight_smile:

I’m not sure if this is somehow more difficult to implement but just looking at the code it should not be.

Oh, I see. It could be a good addition but we must provide a) for server-side rendering. I mean, we cannot assume that we are going to always load a page without errors in the first place.

Right, I did not take that into account :+1: