How do you include a custom jinja filter / macro?

[bgalvao]

I have this function that I cannot find in the list of built in Jinja filters

from os.path import basename

def s3_basename(s3_path) -> str:
    return basename(s3_path)

I would like to register s3_basename and be able to use it inside the copier.yml file.

Is it currently possible? I am asking because so far in the docs, only the built-in jinja filters are accepted.

cc: @gilcardoai

[yajo]

You can add jinja extensions: https://copier.readthedocs.io/en/stable/configuring/#jinja_extensions

[sisp]

I believe @bgalvao is trying to register custom macros that are defined within the template. AFAIK, this isn't possible at the moment, but I believe we could support it. For instance, how about registering local extensions (that can register macros, filters, etc.) via copier.yml like this:

_jinja_extensions:
  # Either as a string ...
  - "jinja/extension.py:MyJinjaExtension"
  # ... or as a YAML mapping
  - jinja/extension.py: MyJinjaExtension

Here, the path jinja/extension.py is part of the template repo (it's just an example, it can be any path to a Python file in that repo). And MyJinjaExtension is a subclass of jinja2.ext.Extension that is defined in jinja/extension.py.

This syntax is somewhat inspired by, e.g., Poetry's scripts section.

[bgalvao]

I am a noob in Jinja. I will check Jinja extensions by yajo and brb

[pawamoy]

@sisp, @bgalvao that's actually what the copier-templates-extensions extension allows to do!

_jinja_extensions:
- copier_templates_extensions.TemplateExtensionLoader
- extensions/s3basename.py:S3BasenameExtension

S3BasenameExtension can then be written like this, in extensions/s3basename.py:

from os.path import basename
from jinja2.ext import Extension

def s3_basename(s3_path) -> str:
    return basename(s3_path)

class S3BasenameExtension(Extension):
    def __init__(self, environment):
        super().__init__(environment)
        environment.filters["s3_basename"] = s3_basename

[sisp]

@pawamoy Ahh, I didn't know that. Even better. The only thing is, it needs to be installed separately.

[bgalvao]

well, for what I needed, the included ansible extensions had a basename kind of function, so it works for me! Thanks!

fastapi_s3_model_folder:
    type: str
    help: The name of the subdirectory leaf from the fastapi_bucket_name
    default: "{{ fastapi_bucket_name | basename }}"
    when: false