How to use JSON to Flow
- Paste a representative JSON sample, ideally one with all the optional fields filled in.
- Set the name of the root type, and decide whether you want helper code as well or types only.
- Copy the generated Flow code into your project.
About JSON to Flow
Writing model classes by hand for a big JSON payload is dull, and it is where typos creep in. Paste a sample here and the generator works out the structure: which fields exist, which are objects, which are arrays and what type each value has. The output is Flow type aliases for objects and arrays.
The output starts with the @flow comment so that the checker picks it up. Everything runs in your browser, so your sample data stays on your machine.
Using the generated code
Import the types in a file with the @flow pragma, for example const data: Root = JSON.parse(text).
Optional values use the maybe type, ?string, which allows null and undefined.