From 3a4086e22f2a4c837635f14bb6e9ae056299dc6c Mon Sep 17 00:00:00 2001
From: Andrew Beresford <aberesford@equalexperts.com>
Date: Fri, 6 Apr 2018 15:58:45 +0100
Subject: [PATCH] Expose the target commit ID through the tag API

This is useful for annotated tags, where the deferenced target is not the same as the tag object. At the moment there is no way to differentiate the two through the tag API.

This change adds a "target" property and leaves the existing "commit" property alone so that existing behaviour is not altered.
---
 changelogs/unreleased/feature-add_target_to_tags.yml | 5 +++++
 doc/api/tags.md                                      | 6 ++++++
 lib/api/entities.rb                                  | 2 +-
 spec/fixtures/api/schemas/public_api/v4/tag.json     | 1 +
 4 files changed, 13 insertions(+), 1 deletion(-)
 create mode 100644 changelogs/unreleased/feature-add_target_to_tags.yml

diff --git a/changelogs/unreleased/feature-add_target_to_tags.yml b/changelogs/unreleased/feature-add_target_to_tags.yml
new file mode 100644
index 00000000000..75816005e1f
--- /dev/null
+++ b/changelogs/unreleased/feature-add_target_to_tags.yml
@@ -0,0 +1,5 @@
+---
+title: Expose the target commit ID through the tag API
+merge_request:
+author:
+type: added
diff --git a/doc/api/tags.md b/doc/api/tags.md
index fa25dc76452..4af096c3c0c 100644
--- a/doc/api/tags.md
+++ b/doc/api/tags.md
@@ -42,6 +42,7 @@ Parameters:
       "description": "Amazing release. Wow"
     },
     "name": "v1.0.0",
+    "target": "2695effb5807a22ff3d138d593fd856244e155e7",
     "message": null
   }
 ]
@@ -73,6 +74,7 @@ Example Response:
 {
   "name": "v5.0.0",
   "message": null,
+  "target": "60a8ff033665e1207714d6670fcd7b65304ec02f",
   "commit": {
     "id": "60a8ff033665e1207714d6670fcd7b65304ec02f",
     "short_id": "60a8ff03",
@@ -132,12 +134,16 @@ Parameters:
     "description": "Amazing release. Wow"
   },
   "name": "v1.0.0",
+  "target: "2695effb5807a22ff3d138d593fd856244e155e7",
   "message": null
 }
 ```
 The message will be `null` when creating a lightweight tag otherwise
 it will contain the annotation.
 
+The target will contain the tag objects ID when creating annotated tags,
+otherwise it will contain the commit ID when creating lightweight tags.
+
 In case of an error,
 status code `405` with an explaining error message is returned.
 
diff --git a/lib/api/entities.rb b/lib/api/entities.rb
index e35b1a0ff63..8aad320e376 100644
--- a/lib/api/entities.rb
+++ b/lib/api/entities.rb
@@ -928,7 +928,7 @@ module API
     end
 
     class Tag < Grape::Entity
-      expose :name, :message
+      expose :name, :message, :target
 
       expose :commit, using: Entities::Commit do |repo_tag, options|
         options[:project].repository.commit(repo_tag.dereferenced_target)
diff --git a/spec/fixtures/api/schemas/public_api/v4/tag.json b/spec/fixtures/api/schemas/public_api/v4/tag.json
index 52cfe86aeeb..10d4edb7ffb 100644
--- a/spec/fixtures/api/schemas/public_api/v4/tag.json
+++ b/spec/fixtures/api/schemas/public_api/v4/tag.json
@@ -10,6 +10,7 @@
     "name": { "type": "string" },
     "message": { "type": ["string", "null"] },
     "commit": { "$ref": "commit/basic.json" },
+    "target": { "type": "string" },
     "release": {
       "oneOf": [
         { "type": "null" },