Trigger diferent jobs depending on pull request type

Question

I'm trying to reduce the amount of files I have for my workflows from 4 to 1. And with that my on is like this:

on:
  pull_request:
    types: [opened, synchronize, closed]
  push:
    branches: [master]

I know it's possible to use if in workflows but looking at the documentation I didn't find which parameters I should use to trigger the correct jobs when:

• Pull request is opened
• Pull request is closed
• Push is made to a existing pull request
• Push is made to a brach

Answer 1

The piece of documentation that touches on how to use if is this one.

You can use it at the job level. Consider the following example to execute a job only when the PR has been closed and merged (not just closed):

name: Build Your App

on:
  pull_request:
    types: [ closed ]
    
jobs:
  build:
    # this job will only run if the PR has been merged, not just 'closed'
    if: github.event.pull_request.merged == true
    runs-on: ubuntu-latest
    steps:

    - name: Checkout repository
      uses: actions/checkout@v2
      with:
        fetch-depth: '0'

And you can also use it at the step level, to execute or not the step based on the {{ expression }} evaluation, as the documentation shows.

Based on your ask, I would use the information on the github.event.* payload. To do that I use to re-create the conditions and triggers on a test repository and print it to the console. Then I know what I have to look for in each kind of event. It's like debugging the events. This is the documentation to do that.