Create Command

The create command generates a new codemod function with the necessary boilerplate.

codegen create rename-function .

Usage

codegen create NAME PATH [OPTIONS]

Arguments

• NAME: The name of the codemod to create (e.g., “rename-function”)
• PATH: The path where the codemod should be created (e.g., ”.” for current directory)

Options

• --description, -d: A description of what the codemod should do. This will be used to generate an AI-powered implementation.

Generated Files

When you run codegen create rename-function ., it creates:

.codegen/
└── codemods/
    └── rename_function/
        ├── rename_function.py              # The codemod implementation
        └── rename_function-system-prompt.txt  # System prompt (if --description used)

The generated codemod will have this structure:

import codegen
from codegen import Codebase

@codegen.function("rename-function")
def run(codebase: Codebase):
    """Add a description of what this codemod does."""
    # Add your code here
    print('Total files: ', len(codebase.files))
    print('Total functions: ', len(codebase.functions))
    print('Total imports: ', len(codebase.imports))

if __name__ == "__main__":
    print('Parsing codebase...')
    codebase = Codebase("./")

    print('Running...')
    run(codebase)

Examples

Create a basic codemod:

codegen create rename-function .

Create with an AI-powered implementation:

codegen create rename-function . -d "Rename the getUserData function to fetchUserProfile"

Next Steps

After creating a codemod:

1. Edit the implementation in the generated .py file
2. Test it with codegen run rename-function
3. Deploy it for team use with codegen deploy rename-function

Common Issues

If you see “File already exists”:

1. Choose a different name for your codemod, or
2. Use the --overwrite flag to replace the existing file

The codemod name will be converted to snake_case for the Python file (e.g., update-imports becomes update_imports.py).