How to trigger github action when PR is merged and Workflow dispatch?

I was trying to implement github actions when PR is merged. It also had a part of workflow dispatch.

name: Deploy to DEV
on:
  push:
    branches:
      - dev
    paths-ignore:
      - '.github/**'
  workflow_dispatch:
jobs:
  Deploy-to-Dev:
    if: github.event.pull_request.merged == true
    runs-on: ubuntu-22.04

So what i wanted to know was will Deploy-t0-Dev run or skips? If i trigger from workflow dispatch? I currently couldn't test it due to client requirements. Thanks

For readability and semantics sake, you can use pull_request event trigger instead of push.

Among others, pull_request event has closed activity type:

When a pull request merges, the pull request is automatically closed.

And to check if the action is triggered by workflow_dispatch event, you can use GITHUB_EVENT_NAME environment variable.

GITHUB_EVENT_NAME: The name of the event that triggered the workflow. For example, workflow_dispatch

reference

Your code would like this:

name: Deploy to DEV
on:
  workflow_dispatch: {}

  pull_request:
    branches:
      - dev
    paths-ignore:
      - '.github/**'
    types:
      - closed

jobs:
  Deploy-to-Dev:
    if: github.event_name == 'workflow_dispatch' || github.event.pull_request.merged == true
    runs-on: ubuntu-22.04
    steps:
    - run: |
        echo The PR was merged

Example code snippet reference

Above workflow runs either when pull request is merged or when workflow is triggered manually via workflow_dispatch event.