query-parameters-api-custom-commands

name	query-parameters-api-custom-commands
description	How to author custom commands for the query-parameters-api CLI using the co-generated SDK. Use when this capability is needed.
metadata	{"author":"fern-api"}

Custom Commands for query-parameters-api

Overview

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

Adding a Custom Command

1. Edit cli/query-parameters-api/custom.rs

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

use query_parameters_api_sdk::api::*;

pub fn register(app: CliApp) -> CliApp {
    let app = app.command(
        clap::Command::new("my-command")
            .about("Description of your command")
            .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.resource.get(id),
            )?;
            println!("{}", serde_json::to_string_pretty(&result).unwrap());
            Ok(())
        },
    );
    app
}

2. Available SDK Clients

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

(Sub-clients are derived from the API spec at generation time.)

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 query_parameters_api_sdk::api::*;

Regeneration Safety

File	Regenerated?	Notes
cli/query-parameters-api/custom.rs	No	Protected by .fernignore
cli/query-parameters-api/sdk_glue.rs	Yes	Bridges AppContext → SDK client
cli/query-parameters-api/main.rs	Yes	Calls custom::register(app)
query-parameters-api-sdk/	Yes	Co-generated typed SDK crate
query-parameters-api-types/	Yes	Co-generated typed models

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
query-parameters-api <your-command> [args]

# Run with verbose output for debugging
RUST_LOG=debug query-parameters-api <your-command> [args]

---

Source: fern-api/fern — distributed by TomeVault.