nx-generate

Run Nx Generator

Nx generators are powerful tools that scaffold projects, make automated code migrations or automate repetitive tasks in a monorepo. They ensure consistency across the codebase and reduce boilerplate work.

This skill applies when the user wants to:

• Create new projects like libraries or applications
• Scaffold features or boilerplate code
• Run workspace-specific or custom generators
• Do anything else that an nx generator exists for

Key Principles

1. Always use --no-interactive - Prevents prompts that would hang execution
2. Read the generator source code - The schema alone is not enough; understand what the generator actually does
3. Match existing repo patterns - Study similar artifacts in the repo and follow their conventions
4. Verify with lint/test/build/typecheck etc. - Generated code must pass verification. The listed targets are just an example, use what's appropriate for this workspace.

Steps

1. Discover Available Generators

Use the Nx CLI to discover available generators:

• List all generators for a plugin: npx nx list @nx/react
• View available plugins: npx nx list

This includes plugin generators (e.g., @nx/react:library) and local workspace generators.

2. Match Generator to User Request

Identify which generator(s) could fulfill the user's needs. Consider what artifact type they want, which framework is relevant, and any specific generator names mentioned.

IMPORTANT: When both a local workspace generator and an external plugin generator could satisfy the request, always prefer the local workspace generator. Local generators are customized for the specific repo's patterns.

If no suitable generator exists, you can stop using this skill. However, the burden of proof is high—carefully consider all available generators before deciding none apply.

3. Get Generator Options

Use the --help flag to understand available options:

npx nx g @nx/react:library --help

Pay attention to required options, defaults that might need overriding, and options relevant to the user's request.

Library Buildability

Default to non-buildable libraries unless there's a specific reason for buildable.

Non-buildable libs:

• Export .ts/.tsx source directly
• Consumer's bundler compiles them
• Faster dev experience, less config

Buildable libs:

• Have their own build target
• Useful for stable libs that rarely change (cache hits)
• Required for npm publishing

If unclear, ask the user: "Should this library be buildable (own build step, better caching) or non-buildable (source consumed directly, simpler setup)?"

4. Read Generator Source Code

This step is critical. The schema alone does not tell you everything. Reading the source code helps you:

• Know exactly what files will be created/modified and where
• Understand side effects (updating configs, installing deps, etc.)
• Identify behaviors and options not obvious from the schema
• Understand how options interact with each other

To find generator source code:

• For plugin generators: Use node -e "console.log(require.resolve('@nx/<plugin>/generators.json'));" to find the generators.json, then locate the source from there
• If that fails, read directly from node_modules/<plugin>/generators.json
• For local generators: Typically in tools/generators/ or a local plugin directory. Search the repo for the generator name.

After reading the source, reconsider: Is this the right generator? If not, go back to step 2.

⚠️ --directory flag behavior can be misleading. It should specify the full path of the generated library or component, not the parent path that it will be generated in.

# ✅ Correct - directory is the full path for the library
nx g @nx/react:library --directory=libs/my-lib
# generates libs/my-lib/package.json and more
 
# ❌ Wrong - this will create files at libs and libs/src/...
nx g @nx/react:library --name=my-lib --directory=libs
# generates libs/package.json and more

5. Examine Existing Patterns

Before generating, examine the target area of the codebase:

• Look at similar existing artifacts (other libraries, applications, etc.)
• Identify naming conventions, file structures, and configuration patterns
• Note which test runners, build tools, and linters are used
• Configure the generator to match these patterns

6. Dry-Run to Verify File Placement

Always run with --dry-run first to verify files will be created in the correct location:

npx nx g @nx/react:library --name=my-lib --dry-run --no-interactive

Review the output carefully. If files would be created in the wrong location, adjust your options based on what you learned from the generator source code.

Note: Some generators don't support dry-run (e.g., if they install npm packages). If dry-run fails for this reason, proceed to running the generator for real.

7. Run the Generator

Execute the generator:

nx generate <generator-name> <options> --no-interactive

Tip: New packages often need workspace dependencies wired up (e.g., importing shared types, being consumed by apps). The link-workspace-packages skill can help add these correctly.

8. Modify Generated Code (If Needed)

Generators provide a starting point. Modify the output as needed to:

• Add or modify functionality as requested
• Adjust imports, exports, or configurations
• Integrate with existing code patterns

Important: If you replace or delete generated test files (e.g., *.spec.ts), either write meaningful replacement tests or remove the test target from the project configuration. Empty test suites will cause nx test to fail.

9. Format and Verify

Format all generated/modified files:

nx format --fix

This example is for built-in nx formatting with prettier. There might be other formatting tools for this workspace, use these when appropriate.

Then verify the generated code works. Keep in mind that the changes you make with a generator or subsequent modifications might impact various projects so it's usually not enough to only run targets for the artifact you just created.

# these targets are just an example!
nx run-many -t build,lint,test,typecheck

These targets are common examples used across many workspaces. You should do research into other targets available for this workspace and its projects. CI configuration is usually a good guide for what the critical targets are that have to pass.

If verification fails with manageable issues (a few lint errors, minor type issues), fix them. If issues are extensive, attempt obvious fixes first, then escalate to the user with details about what was generated, what's failing, and what you've attempted.