copier/docs/creating.md
2023-08-05 20:33:57 +02:00

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# Creating a template
A template is a directory: usually the root folder of a Git repository.
The content of the files inside the project template is copied to the destination
without changes, **unless they end with `.jinja`** (or [your chosen
suffix][templates_suffix]). In that case, the templating engine will be used to render
them.
Jinja2 templating is used. Learn more about it by reading
[Jinja2 documentation](https://jinja.palletsprojects.com/).
If a **YAML** file named `copier.yml` or `copier.yaml` is found in the root of the
project, the user will be prompted to fill in or confirm the default values.
## Minimal example
```tree result="shell"
my_copier_template # your template project
copier.yml # your template configuration
.git/ # your template is a Git repository
{{project_name}} # a folder with a templated name
{{module_name}}.py.jinja # a file with a templated name
{{_copier_conf.answers_file}}.jinja # answers are recorded here
```
```yaml title="copier.yml"
# questions
project_name:
type: str
help: What is your project name?
module_name:
type: str
help: What is your Python module name?
```
```python+jinja title="{{project_name}}/{{module_name}}.py.jinja"
print("Hello from {{module_name}}!")
```
```yaml+jinja title="{{_copier_conf.answers_file}}.jinja"
# Changes here will be overwritten by Copier
{{ _copier_answers|to_nice_yaml -}}
```
Generating a project from this template with `super_project` and `world` as answers for
the `project_name` and `module_name` questions respectively would create in the
following directory and files:
```tree result="shell"
generated_project
super_project
world.py
.copier-answers.yml
```
```python title="super_project/world.py"
print("Hello from world!")
```
```yaml title=".copier-answers.yml"
# Changes here will be overwritten by Copier
_commit: 0.1.0
_src_path: gh:your_account/your_template
project_name: super_project
module_name: world
```
Copier allows much more advanced templating: see the next chapter,
[configuring a template](configuring.md), to see all the configurations options and
their usage.
## Template helpers
In addition to
[all the features Jinja supports](https://jinja.palletsprojects.com/en/3.1.x/templates/),
Copier includes:
- All functions and filters from
[jinja2-ansible-filters](https://gitlab.com/dreamer-labs/libraries/jinja2-ansible-filters/).
- This includes the `to_nice_yaml` filter, which is used extensively in our
context.
- `_copier_answers` includes the current answers dict, but slightly modified to make
it suitable to [autoupdate your project safely][the-copier-answersyml-file]:
- It doesn't contain secret answers.
- It doesn't contain any data that is not easy to render to JSON or YAML.
- It contains special keys like `_commit` and `_src_path`, indicating how the last
template update was done.
- `_copier_conf` includes a representation of the current Copier
<!-- prettier-ignore -->
[Worker][copier.main.Worker] object, also slightly modified:
- It only contains JSON-serializable data.
- You can serialize it with `{{ _copier_conf|to_json }}`.
- ⚠️ It contains secret answers inside its `.data` key.
- Modifying it doesn't alter the current rendering configuration.
- It contains the current commit hash from the template in
`{{ _copier_conf.vcs_ref_hash }}`.
- Contains Operating System-specific directory separator under `sep` key.