How to trim empty lines from commit message?

[thomaseizinger]

We have the following commit message template:

{{ title }}

{{ body | get_section("## Description", "") }}

Pull-Request: #{{ number }}.
{# Here comes some fancy Jinja2 stuff for correctly attributing co-authorship: #}
{% for commit in (commits | unique(False, 'email_author')) | rejectattr("author", "==", author) %}
  {% if commit.parents|length == 1 %}
Co-Authored-By: {{ commit.author }} <{{ commit.email_author }}>
  {% endif %}
{% endfor %}
{# GitHub requires that the `Co-authored-by` lines are AT THE VERY END of a commit, hence nothing must come after this. #}

Here is an example commit that got generated: libp2p/rust-libp2p@b8ceecc

As you can see, there are multiple empty lines. Ideally, I would like to control these empty lines somehow. My expectation was that - because I did not add any empty lines between Pull-Request and the comment - there would be no empty lines. Yet it seems that the template engine adds additional empty lines?

Can this be avoided somehow?

Also, not all our PRs have a ## Description section (or it is empty). Ideally I'd like to somehow avoid additional empty lines in that case.

If we go after https://cbea.ms/git-commit/, then a commit message should never have more than a single empty line as a separator. That is what I want to achieve. Would it be possible to automatically trim additional empty lines from inside the template?

[Kontrolix]

Hi,
There is whitespace control in Jinja. You should probably add a minus to your template like this to avoid rendering it.

{{ title }}

{{ body | get_section("## Description", "") }}

Pull-Request: #{{ number }}.
{# Here comes some fancy Jinja2 stuff for correctly attributing co-authorship: #}
{%- for commit in (commits | unique(False, 'email_author')) | rejectattr("author", "==", author) -%}
  {%- if commit.parents|length == 1 -%}
Co-Authored-By: {{ commit.author }} <{{ commit.email_author }}>
  {%- endif -%}
{%- endfor -%}
{# GitHub requires that the `Co-authored-by` lines are AT THE VERY END of a commit, hence nothing must come after this. #}

Hope it's what you are looking for 😉

[thomaseizinger]

I tried it on https://j2live.ttl255.com/ with the following test-data and it is missing the newlines inbetween. I am working on it in this PR: libp2p/rust-libp2p#4104

commits:
  - email_author: [email protected]
    author: foo
    parents:
      - abc
  - email_author: [email protected]
    author: bar
    parents:
      - abc
  - email_author: [email protected]
    author: bar
    parents:
      - abc
  - email_author: [email protected]
    author: xyz
    parents:
      - abc
      - def
  - email_author: [email protected]
    author: foo
    parents:
      - abc
  - email_author: [email protected]
    author: xyz
    parents:
      - abc
  - email_author: [email protected]
    author: xyz1
    parents:
      - abc
author: test

[Kontrolix]

Hi,

With this template:

{{ title }}

Pull-Request: #{{ number }}.
{# Here comes some fancy Jinja2 stuff for correctly attributing co-authorship: #}
{%- for commit in (commits | unique(False, 'email_author')) | rejectattr("author", "==", author) -%}
  {% if commit.parents|length == 1 %}
Co-Authored-By: {{ commit.author }} <{{ commit.email_author }}>
  {%- endif -%}
{%- endfor -%}

I get this :

[thomaseizinger]

Yeah the trick is to not use - everywhere.

I actually ended up deleting all of this again because it doesn't work with what is currently exposed. See libp2p/rust-libp2p@514e2e9.

[Kontrolix]

Ok, I see, for the record, the co-author will be available directly in data in few weeks.

[thomaseizinger]

Ok, I see, for the record, the co-author will be available directly in data in few weeks.

Yep, waiting for that at the moment, thanks :)