add new base_ref output

README.md

@@ -219,6 +219,7 @@ As seen above, we have a single example step. Perhaps you would actually use a r
 | `fork_full_name` | The full name of the fork in "org/repo" format |
 | `sha` | The commit sha if being used in the context of a pull request |
 | `ref` | The ref if being used in the context of a pull request |
+| `base_ref` | The base ref that the pull request is merging into (if available and run in the context of a pull request) |
 
 ## Allowlist 👩‍🔬
 

__tests__/schemas/action.schema.yml

@@ -250,3 +250,7 @@ outputs:
     description:
       type: string
       required: true
+  base_ref:
+    description:
+      type: string
+      required: true

action.yml

@@ -99,6 +99,8 @@ outputs:
     description: 'The commit sha if being used in the context of a pull request'
   ref:
     description: 'The ref if being used in the context of a pull request'
+  base_ref:
+    description: The base ref that the pull request is merging into (if available and run in the context of a pull request)
 runs:
   using: "node20"
   main: "dist/index.js"

src/functions/prechecks.js

@@ -60,6 +60,11 @@ export async function prechecks(
   var sha = pr.data.head.sha
   var ref = pr.data.head.ref
 
+  // set an output which is the branch name this PR is targeting to merge into
+  const baseRef = pr?.data?.base?.ref
+  core.setOutput('base_ref', baseRef)
+  core.debug(`base_ref: ${baseRef}`)
+
   var forkBypass = false
 
   // Determine whether to use the ref or sha depending on if the PR is from a fork or not