Get Pull Request number when building its merge commit

Travis CI Discussions & Feedback
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1

The Pull Request number environment variable is “false” when the build is merging a Pull Request. Is there any way to retrieve it or it is only available when the current job is a pull request ?

2

Googling “github api merge commit get pull request number” shows that it’s possible to retrieve this information with Github v4 API:

3

In “More options->Requests” in Travis UI (link for your test project), you can see what kinds of requests Github sends to Travis. Then, Event Types & Payloads | GitHub Developer Guide documents what information is available in the payload of each event’s type.
This is the entire information that Travis can potentially expose to a build.

4

The solution I found:

  1. Retrieve all Pull Requests via the GitHub API.
  2. Filter the needed Pull Request using the environment variable TRAVIS_COMMIT and the ‘merge_commit_sha’ property of the Pull Request. (Those two should be equal for the correct Pull Request).
5

Note that this will become increasingly taxing and eventually run afoul of Github API limits as the number of pull requests grows.