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Updating a project

Copier has an "update" feature. It means that, once a project is generated, you can keep updating it with the latest changes that happen in the template.

It's particularly useful when you manage a lot of projects, all generated from the same template, and you want to apply a change to all your projects.

Example: the template fixed a bug in a configuration file. You don't want to apply it manually to your projects.

Update command

To update your project, go into its directory and run:

uvx --with copier-templates-extensions copier update --trust --defaults

Your repository must be clean (no modified files) when running this command.

Flags explained:

  • --trust: Allow the template to run tasks (required for post-update hooks).
  • --defaults: Accept all previous answers without prompting. Remove this flag if you want to review and change your answers.

How it works

Copier will use the previous answers you gave when generating the project, to re-generate it in a temporary directory, compare the two versions, and apply patches to your documents. When it's not sure, or when there's a conflict, it will ask you if you want to skip that change or force it. Your previous answers are stored in the .copier-answers.yml file at the root of the project directory:

📁 my-project
├── 📄 .copier-answers.yml
└── 📄 etc.

And the file looks like this:

# Changes here will be overwritten by Copier
_commit: 0.1.10
_src_path: gh:oedokumaci/python-production-template
author_email: your@email.com
author_fullname: "Your Name"
author_username: your-username
copyright_date: '2025'
copyright_holder: "Your Name"
copyright_holder_email: your@email.com
copyright_license: ISC License
project_description: My awesome project description.
project_name: my-project
python_package_distribution_name: my-project
python_package_import_name: my_project
python_version: "3.13"
repository_name: my-project
repository_namespace: your-username
repository_provider: github.com

Reviewing changes

Since we are generally using Git in our projects, my recommendation is to not think at all and blindly apply every change Copier proposes. Indeed, you'll be able to see the diff with git diff, un-apply changes on whole files with git checkout -- FILE if they are not relevant, or do partial, interactive commits with git add -p or within your IDE interface (PyCharm and VSCode have good support and UX for selecting and committing changes).