generate-function-json.md

Generate JSON Decoder/Encoder

Generate a JSON Decoder (or Encoder) based on a type annotation.

Decoders

Usage

1. Make sure that you have imported Json.Decode
2. Put the cursor on a type annotation where the return type is a Decoder from elm/json (and the function body has not yet been written)
3. Press Option-Enter (macOS; Alt-Enter on Windows/Linux)
4. Select Generate Decoder from the menu

Demo

Encoders

Usage

1. Make sure that you have imported Json.Encode
2. Put the cursor on a type annotation with a signature like encodePerson : Person -> Json.Encode.Value (and the function body has not yet been written)
3. Press Option-Enter (macOS; Alt-Enter on Windows/Linux)
4. Select Generate Encoder from the menu

Demo

Notes

• You can import Json.Encode and Json.Decode using whatever alias you prefer. The plugin will generate code using the same alias.
• When decoding/encoding a type which is not part of elm/core, the plugin will search your project for exposed functions which know how to encode/decode that type and, if found, will use that function.
• The generated decoders use Json.Decode.Pipeline to decode records.