From 07f814984b6285876009af8ec0328c1ac953ebc5 Mon Sep 17 00:00:00 2001
From: Vincent Plannthin <vincent@plannthin.net>
Date: Wed, 26 Apr 2023 15:27:42 +0200
Subject: [PATCH] fix(kitsu-core): Merge meta keys to preserve data

Previously only the meta from the resource identifier object was preserved,
while the resource object meta was discarded, resulting in some cases
where meta would be set to undefined.

The meta keys are now merged instead of picked between, preserving the
largest amount of data possible.
---
 .../kitsu-core/src/deserialise/index.spec.js  | 265 ++++++++++++++++++
 .../kitsu-core/src/linkRelationships/index.js |   7 +-
 2 files changed, 269 insertions(+), 3 deletions(-)

diff --git a/packages/kitsu-core/src/deserialise/index.spec.js b/packages/kitsu-core/src/deserialise/index.spec.js
index 51986f2e..dd0f14d3 100644
--- a/packages/kitsu-core/src/deserialise/index.spec.js
+++ b/packages/kitsu-core/src/deserialise/index.spec.js
@@ -815,6 +815,271 @@ describe('kitsu-core', () => {
       expect(input).toEqual(output)
     })
 
+    it('merges meta from relationship object and resource object', () => {
+      expect.assertions(1)
+
+      const input = JSON.parse(stringify(deserialise({
+        data: [
+          {
+            id: 1,
+            type: 'anime',
+            relationships: {
+              primary_category: {
+                meta: { qux: true },
+                data: { id: 1, type: 'category', meta: { foo: true } }
+              },
+              categories: {
+                meta: { qux: true },
+                data: [ { id: 1, type: 'category', meta: { foo: true } } ]
+              }
+            }
+          },
+          {
+            id: 2,
+            type: 'anime',
+            relationships: {
+              primary_category: {
+                meta: { quux: true },
+                data: { id: 1, type: 'category', meta: { bar: true } }
+              },
+              categories: {
+                meta: { quux: true },
+                data: [ { id: 1, type: 'category', meta: { bar: true } } ]
+              }
+            }
+          },
+          {
+            id: 3,
+            type: 'anime',
+            relationships: {
+              primary_category: {
+                meta: { corge: true },
+                data: { id: 1, type: 'category' }
+              },
+              categories: {
+                meta: { corge: true },
+                data: [ { id: 1, type: 'category' } ]
+              }
+            }
+          },
+          {
+            id: 4,
+            type: 'anime',
+            relationships: {
+              primary_category: {
+                meta: { grault: true },
+                data: { id: 1, type: 'category', meta: { baz: false } }
+              },
+              categories: {
+                meta: { grault: true },
+                data: [ { id: 1, type: 'category', meta: { baz: false } } ]
+              }
+            }
+          }
+        ],
+        included: [ { id: 1, type: 'category', attributes: { title: 'foobar' }, meta: { baz: true } } ]
+      })))
+
+      const output = {
+        data: [
+          {
+            primary_category: {
+              meta: { qux: true },
+              data: {
+                id: 1,
+                type: 'category',
+                title: 'foobar',
+                meta: {
+                  baz: true,
+                  foo: true
+                }
+              }
+            },
+            categories: {
+              meta: { qux: true },
+              data: [
+                {
+                  id: 1,
+                  meta: {
+                    baz: true,
+                    foo: true
+                  },
+                  title: 'foobar',
+                  type: 'category'
+                }
+              ]
+            },
+            id: 1,
+            type: 'anime'
+          },
+          {
+            primary_category: {
+              meta: { quux: true },
+              data: {
+                id: 1,
+                type: 'category',
+                title: 'foobar',
+                meta: {
+                  baz: true,
+                  bar: true
+                }
+              }
+            },
+            categories: {
+              meta: { quux: true },
+              data: [
+                {
+                  id: 1,
+                  meta: {
+                    baz: true,
+                    bar: true
+                  },
+                  title: 'foobar',
+                  type: 'category'
+                }
+              ]
+            },
+            id: 2,
+            type: 'anime'
+          },
+          {
+            primary_category: {
+              meta: { corge: true },
+              data: {
+                id: 1,
+                type: 'category',
+                title: 'foobar',
+                meta: {
+                  baz: true
+                }
+              }
+            },
+            categories: {
+              meta: { corge: true },
+              data: [
+                {
+                  id: 1,
+                  title: 'foobar',
+                  type: 'category',
+                  meta: {
+                    baz: true
+                  }
+                }
+              ]
+            },
+            id: 3,
+            type: 'anime'
+          },
+          {
+            primary_category: {
+              meta: { grault: true },
+              data: {
+                id: 1,
+                type: 'category',
+                title: 'foobar',
+                meta: {
+                  baz: false
+                }
+              }
+            },
+            categories: {
+              meta: { grault: true },
+              data: [
+                {
+                  id: 1,
+                  title: 'foobar',
+                  type: 'category',
+                  meta: {
+                    baz: false
+                  }
+                }
+              ]
+            },
+            id: 4,
+            type: 'anime'
+          }
+        ]
+      }
+
+      expect(input).toEqual(output)
+    })
+
+    it('preserves meta from included resource object', () => {
+      expect.assertions(1)
+
+      const input = JSON.parse(stringify(deserialise({
+        data: {
+          id: '1',
+          type: 'users',
+          relationships: {
+            followers: {
+              links: {
+                self: 'https://kitsu.example/users/1/relationships/followers',
+                related: 'https://kitsu.example/users/1/followers'
+              },
+              data: [ {
+                type: 'follows',
+                id: '1'
+              } ]
+            }
+          }
+        },
+        included: [
+          {
+            id: '1',
+            type: 'follows',
+            attributes: { a: 123 },
+            links: {
+              self: 'https://kitsu.example/follows/1'
+            },
+            meta: { value: 1 },
+            relationships: {
+              follower: {
+                links: {
+                  self: 'https://kitsu.io/follows/1/relationships/follower',
+                  related: 'https://kitsu.io/follows/1/follower'
+                }
+              }
+            }
+          }
+        ]
+      })))
+
+      const output = {
+        data: {
+          id: '1',
+          type: 'users',
+          followers: {
+            links: {
+              self: 'https://kitsu.example/users/1/relationships/followers',
+              related: 'https://kitsu.example/users/1/followers'
+            },
+            data: [
+              {
+                id: '1',
+                type: 'follows',
+                a: 123,
+                links: {
+                  self: 'https://kitsu.example/follows/1'
+                },
+                meta: {
+                  value: 1
+                },
+                follower: {
+                  links: {
+                    self: 'https://kitsu.io/follows/1/relationships/follower',
+                    related: 'https://kitsu.io/follows/1/follower'
+                  }
+                }
+              }
+            ]
+          }
+        }
+      }
+
+      expect(input).toEqual(output)
+    })
+
     it('Deserializes nested single circular resource', () => {
       expect.assertions(1)
 
diff --git a/packages/kitsu-core/src/linkRelationships/index.js b/packages/kitsu-core/src/linkRelationships/index.js
index a085ed9c..81063575 100644
--- a/packages/kitsu-core/src/linkRelationships/index.js
+++ b/packages/kitsu-core/src/linkRelationships/index.js
@@ -21,7 +21,6 @@ function link ({ id, type, meta }, included, previouslyLinked, relationshipCache
   if (filtered.relationships) {
     linkRelationships(filtered, included, previouslyLinked, relationshipCache)
   }
-  if (meta) filtered.meta = meta
 
   return deattribute(filtered)
 }
@@ -47,7 +46,7 @@ function linkArray (data, included, key, previouslyLinked, relationshipCache) {
   for (const resource of data.relationships[key].data) {
     const cache = previouslyLinked[`${resource.type}#${resource.id}`]
     let relationship = cache || link(resource, included, previouslyLinked, relationshipCache)
-    if (resource.meta !== relationship.meta) relationship = { ...relationship, meta: resource.meta }
+    if (resource.meta || relationship.meta) { relationship = { ...relationship, meta: { ...relationship.meta, ...resource.meta } } }
     data[key].data.push(relationship)
   }
 
@@ -75,7 +74,7 @@ function linkObject (data, included, key, previouslyLinked, relationshipCache) {
     if (!isDeepEqual(cache.meta, resource.meta)) {
       resourceCache = {
         ...cache,
-        meta: resource.meta
+        meta: { ...cache.meta, ...resource.meta }
       }
     } else {
       resourceCache = cache
@@ -86,6 +85,8 @@ function linkObject (data, included, key, previouslyLinked, relationshipCache) {
     data[key].data = link(resource, included, previouslyLinked, relationshipCache)
   }
 
+  if (resource.meta || data[key].data.meta) { data[key].data = { ...data[key].data, meta: { ...data[key].data.meta, ...resource.meta } } }
+
   const cacheKey = `${data.type}#${data.id}#${key}`
   const relationships = relationshipCache[cacheKey] || data.relationships[key]
   if (!relationshipCache[cacheKey]) relationshipCache[cacheKey] = relationships