null-type-custom-commands

name: null-type-custom-commands description: How to author custom commands for the null-type CLI using the co-generated SDK.

Custom Commands for null-type

Overview

The null-type CLI supports user-authored custom commands that are compiled into the binary alongside the auto-generated API commands. Custom commands get a fully-wired SDK client that inherits the CLI's auth, retries, TLS, base URL, and global headers — zero configuration required.

Architecture

cli/null-type/custom.rs    ← Your command handlers (protected by .fernignore)
cli/null-type/sdk_glue.rs  ← Generated bridge: sdk_client() + block_on()
cli/null-type/main.rs      ← Generated entrypoint (calls custom::register)
null-type-sdk/             ← Co-generated typed SDK crate
null-type-types/           ← Co-generated typed model crate

Adding a Custom Command

1. Edit cli/null-type/custom.rs

This file is protected by .fernignore — fern generate will never overwrite it. Register commands in the register() function:

use null_type_sdk::api::*;

pub fn register(app: CliApp) -> CliApp {
    let app = app.command(
        clap::Command::new("get")
            .about("Get User")
            .arg(clap::Arg::new("id").required(true))
        ,
        |matches, ctx| {
            let id = matches.get_one::<String>("id").unwrap();
            let client = super::sdk_glue::sdk_client(ctx);
            let result = super::sdk_glue::block_on(
                client.users.get(id),
            )?;
            println!("{}", serde_json::to_string_pretty(&result).unwrap());
            Ok(())
        },
    );
    app
}

Then build and test:

cargo build
null-type get <id>

2. Available SDK Clients

The sdk_glue::sdk_client(ctx) call returns a null_type_sdk::api::Client with the following sub-clients:

3. Key Patterns

Get the SDK client (execution-sharing, fully authenticated):

let client = super::sdk_glue::sdk_client(ctx);

Run an async SDK call from a sync handler:

let result = super::sdk_glue::block_on(
    client.some_resource.some_method(args),
)?;

Use typed models for request/response serialization:

use null_type_sdk::api::*;

Regeneration Safety

After running fern generate, your custom.rs is preserved. All generated code (SDK, types, glue, main.rs) is updated to match the latest API spec. If the SDK surface changes (renamed methods, new sub-clients), update your custom.rs to match.

Build & Test

# Build the CLI (includes custom commands)
cargo build

# Run your custom command
null-type <your-command> [args]

# Run with verbose output for debugging
RUST_LOG=debug null-type <your-command> [args]