Determine if a new PR was created

[sheurich]

Subject of the issue

I would like to inform the next step in the workflow whether create-pull-request created a new PR, updated an existing PR or (successfully) did nothing. Ideally this would be implemented as an output from the action step.

This could be used e.g. by a subsequent non-idempotent step which should only run when a new PR has been created.

Steps to reproduce

The current set of outputs do not provide enough information about the action status; the pull-request-number and pull-request-url outputs are the same regardless of new, update or no-op activity.

[peter-evans]

Hi @sheurich

I've avoided adding this up to now because it is not quite as easy at it appears to implement. Firstly, the action handles create/update/delete of the git branch, and the create/update of the pull request on GitHub's API. So what use cases like yours are interested in is presumably a combination of these states. Secondly, there is the problem of what counts as "updated." For the update of the PR on GitHub's API the action doesn't check the current state of the title, body, labels, etc., it just sends a PATCH which would overwrite if there were changes. If there wasn't any changes the action would still consider that "updated." I'm not sure if users would find that satisfactory.

If would be helpful if you could explain what subsequent non-idempotent step you are planning to run.

[sheurich]

If would be helpful if you could explain what subsequent non-idempotent step you are planning to run.

👋🏽 @peter-evans

I want to notify an external system, e.g. using the Jira API to create a ticket, only when a PR is created or updated.

One use-case might be tracking an upstream repository and updating a fork using the c-p-r action. Running this on a timed basis should create a ticket for a person to review the PR when created or when updated with additional upstream changes.

[peter-evans]

Would it work for you if the action returned an output with one of following values?

created - The action only returns this if a new pull request has been created. What this means is that a new PR is created via the GitHub API, regardless of the state of the pull request branch.
updated - The action returns this if the pull request branch is updated. This means there are changes to the PR diff. (This will not be returned if other inputs like title, body, labels, etc., are updated.)
closed - The action returns this when it deletes the pull request branch. This causes GitHub to automatically close the associated pull request if it exists.
- The action returns an empty string if none of the above are true.

[sheurich]

Your proposed change would fix my issue perfectly. Thanks!

[peter-evans]

Released as v3.8.0 / v3.