Is there an example of how to correctly make `fetch` requests in ReScript?

How to correctly create a binding to fetch with the typed response?

You can use the existing bindings

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Why not fetch external binding? Is it so difficult to type fetch and it’s response?

It’s not super difficult to do a one-off binding:

But it is difficult to do a feature-complete binding of everything that the Fetch API supports (e.g. abort). So IMHO it’s better to reuse the work that’s already been done and tested by others.

I just trying to learn how to work with the language and interop. Thank you.

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@yawaramin I looked at your code and at bs-fetch and didn’t find any code that would show how to type data coming from fetch response. Is it possible?

It should be. If the response data is JSON serialized to string, then the Fetch API’s Response class has a json method which conveniently parses the string into a JSON object. Then, you would have a decoder function to transform the JSON object into a domain-specific type. This is shown in my example. There are a few decoder libraries, e.g.:

  • bs-json: allows building decoders by composing together simple components.
  • decco: auto-derives a decoder by looking at the shape of the type. Convenient but has some limitations. This is the one I used in my example.

Hi @osenvosem I am also learning ReScript. Here is some simple example code I wrote that fetches and parses JSON data.

This example uses bs-json instead of decco.


@yawaramin didn’t know that it must be decoded. Thank you.

@kevanstannard your post is exactly what I needed. Thank you.