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

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

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You can use the existing bindings https://github.com/reasonml-community/bs-fetch/

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

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It’s not super difficult to do a one-off binding: https://github.com/yawaramin/fullstack-reason/blob/70a213e9280cd481d327250733d90693d7246e6c/frontend/ShowBob.re#L3

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.

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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?

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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.
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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.

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

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