Support Multiple Templates per Repository

[BrutalSimplicity]

I would like for copier to support multiple templates in a given repository by allowing the subdirectory of the repository to be specified with the vcs ref, and supporting updates by filtering commit history based on the subdirectory and a user-specified suffix/prefix for tags.

Alternatively, I can continue to use single repo per template approach that makes template management more difficult on the user and developer.

[BrutalSimplicity]

I've seen this workaround, https://copier.readthedocs.io/en/stable/configuring/#subdirectory, but I don't believe that will support the use case of having different questions per template. Unless it's possible to pull in questions from each subdirectory. If so, that would be 💯

[bittner]

To showcase a real use case, I have a Python TDD tooling and education project that provides project examples in a subfolder. Since developers are lazy I want them to be able to generate one of those "flavors" in the subfolder directly off GitHub, i.e. avoiding to have to clone the project first. Quite a few developers would certainly stop here otherwise for trying the project out.

The user experience I'm after is a simple, intuitive one-liner, e.g.

copier https://github.com/foo/bar examples/one cli-example

Note that there is now an explanation for the "1 template = 1 Git repository" recommendation in the documentation, along with a suggested solution.

With this questions file and this directory structure, the user will be prompted which Python engine to use, and the project will be generated using the subdirectory whose name matches the answer from the user:

This sounds promising! I'm curious whether it has my use case covered. 👀 🤖

[BrutalSimplicity]

nvm, it's in the docs, https://copier.readthedocs.io/en/stable/configuring/#include-other-yaml-files. I think I can work with the combination of those two options.

[mshafer-NI]

@BrutalSimplicity, if you figure out a working example, I would be interested in seeing it.

[BrutalSimplicity]

Well, I can open this back up. Do you mean the original support in the ticket, or a setup that the configuration supports?

[mshafer-NI]

An example layout, I'm interested doing something similar.

[BrutalSimplicity]

Hmm, ok. I assume you've seen this.

[mshafer-NI]

Yes, I played with putting extra copier.yml files in the _subdirectory, but didn't seem to get anywhere with that.

[mshafer-NI]

(I am currently including a handful of files in the top level copier.yml to separate out my questions and each question does a when based on the _subdirectory parameter); but this has the downside of everything winding up in every answers file.

[yajo]

Maybe yaml anchors can help you reducing repetition.

[icj217]

I've come up with a somewhat feasible approach to multiple templates in a repository (possible once a release is created that includes this merged PR)

Basically, the repo will contain a single copier.yml file containing a single required question named template indicating the template to use, and then template-specific questions below it that are conditional.

# copier.yml

# Save answers to file namespaced by selected template
_answers_file: ".copier-answers.{{ template }}.yml"
# Store each template under separate subdirectory
_subdirectory: "{{ template }}"
# Don't include the README
_exclude:
  - README.md

template:
  type: str
  choices:
    - foo
    - bar
    - baz

# foo questions

foo_question1:
  type: str
  when: &foo
    "{{ template == 'foo' }}"

foo_question2:
  type: str
  when: *foo

# bar questions

bar_question1:
  type: str
  when: &bar
    "{{ template == 'bar' }}"

bar_question2:
  type: str
  when: *bar

# baz questions

baz_question1:
  type: str
  when: &baz
    "{{ template == 'baz' }}"

baz_question2:
  type: str
  when: *baz

For each choice in template, you create a separate directory with that name containing your template files + and answers file i.e.

copier.yml
foo/
  < files >
  {{_copier_conf.answers_file}}.jinja
bar/
  < files >
  {{_copier_conf.answers_file}}.jinja
baz/
  < files >
  {{_copier_conf.answers_file}}.jinja

This allows you to choose from multiple templates stored in the same repository and ensure that each template choice saves its answers to its own namespaced answers file e.g. .copier-answers.foo.yml