openapi-request-body-ref-custom-commands

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How to author custom commands for the openapi-request-body-ref CLI using the co-generated SDK.

fern-api By fern-api schedule Updated 6/8/2026

name: openapi-request-body-ref-custom-commands description: How to author custom commands for the openapi-request-body-ref CLI using the co-generated SDK.

Custom Commands for openapi-request-body-ref

Overview

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

Adding a Custom Command

1. Edit cli/openapi-request-body-ref/custom.rs

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

use openapi_request_body_ref_sdk::api::*;

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

Then build and test:

cargo build
openapi-request-body-ref get-catalog-image <image_id>

2. Available SDK Clients

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

Field Type Description
client.vendor openapi_request_body_ref_sdk::api::VendorClient vendor operations
client.catalog openapi_request_body_ref_sdk::api::CatalogClient catalog operations
client.team_member openapi_request_body_ref_sdk::api::TeamMemberClient team_member operations

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 openapi_request_body_ref_sdk::api::*;

Regeneration Safety

File Regenerated? Notes
cli/openapi-request-body-ref/custom.rs No Protected by .fernignore
cli/openapi-request-body-ref/sdk_glue.rs Yes Bridges AppContext → SDK client
cli/openapi-request-body-ref/main.rs Yes Calls custom::register(app)
openapi-request-body-ref-sdk/ Yes Co-generated typed SDK crate
openapi-request-body-ref-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
openapi-request-body-ref <your-command> [args]

# Run with verbose output for debugging
RUST_LOG=debug openapi-request-body-ref <your-command> [args]
Install via CLI
npx skills add https://github.com/fern-api/fern --skill openapi-request-body-ref-custom-commands
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