elm-client-gen-cli

Reference CLI for elm-client-gen. Walks every type registered via #[derive(ElmType)], groups by Elm module path, and writes one .elm file per module to a directory.

This is a thin wrapper around elm-client-gen-builder with the default configuration. Most real projects outgrow it quickly and ship their own codegen binary (see below).

Install

cargo install elm-client-gen-cli

This installs the elm-client-gen binary.

Usage

elm-client-gen --output ./src                        # write every registered type to ./src
elm-client-gen --output ./src --types Person Order   # filter to specific type names
elm-client-gen --output ./src --dry-run              # print modules to stdout instead of writing

Options:

Flag	Meaning
`-o, --output <DIR>`	Output directory for generated `.elm` files. Required.
`-t, --types <NAMES>...`	Filter to specific Elm type names. Omit for all registered types.
`--dry-run`	Print to stdout instead of writing files.
`-h, --help`	Print help.

The CLI uses the default BuildStrategy (emit decoder + encoder for every type), the default MaybeEncoderRef (Json.Encode.Extra.maybe), an empty TypeOverrides, and no HTTP endpoint codegen.

Linking your schema crate

Because #[derive(ElmType)] registers types via inventory's link-time collector, any crate that only contributes derived types must be referenced from the binary that runs codegen. The reference CLI is intentionally project-agnostic and doesn't import any user crate.

If your schema lives in the same crate as your codegen entry point this isn't an issue, and you can use the published elm-client-gen binary directly. Otherwise, rustc will dead-strip the schema rlib and the registry will be empty.

The standard fix is to fork: copy the body of crates/elm-client-gen-cli/src/main.rs from this repo into your own binary and add a use my_schema_crate as _; at the top. The CLI's entry point is small on purpose so this is cheap.

Customization

The reference CLI has no flags for:

project-specific type overrides (e.g. BigDecimal -> String),
custom BuildStrategy rules (e.g. skip encoders for read-only types tagged "response"),
custom encodeMaybe location,
emitting Elm request functions from #[elm_endpoint(...)] handlers,
running a drift check against a committed tree.

For any of those, write your own binary that calls elm-client-gen-builder directly. See the workspace README for a minimal template.

License