From 68a9238937c158eadf9ac6ced28f31e66a4f6a88 Mon Sep 17 00:00:00 2001
From: ryanxwelch <ryan.x.welch@gmail.com>
Date: Fri, 27 Jan 2017 11:26:49 -0500
Subject: [PATCH 1/3] fix(serializer): remove duplicate includes from
 serializer

Proposed resolution to the following issue:
https://github.com/digitalsadhu/loopback-component-jsonapi/issues/111
---
 lib/serializer.js | 20 +++++++++++++++++++-
 1 file changed, 19 insertions(+), 1 deletion(-)

diff --git a/lib/serializer.js b/lib/serializer.js
index de94d14..fe9ccfa 100644
--- a/lib/serializer.js
+++ b/lib/serializer.js
@@ -379,7 +379,25 @@ function handleIncludes (resp, includes, relations, app) {
   })
 
   if (embedded.length) {
-    resp.included = _.flattenDeep(embedded)
+    // This array may contain duplicate models if the same item is referenced multiple times in 'data'
+    let duplicate = _.flattenDeep(embedded)
+    // So begin with an empty array that will only contain unique items
+    let unique = []
+    // Iterate through each item in the first array
+    duplicate.forEach(function(d){
+      // Count the number of items in the unique array with matching 'type' AND 'id'
+      // Since we're adhering to the JSONAPI spec, both 'type' and 'id' can assumed to be present
+      // Both 'type' and 'id' are needed for comparison because we could theoretically have objects of different
+      // types who happen to have the same 'id', and those would not be considered duplicates
+      let count = unique.filter(function(u){
+        return (u.type === d.type) && (u.id === d.id)
+      }).length;
+      // If there are no matching entries, then add the item to the unique array
+      if (count === 0) {
+        unique.push(d)
+      }
+    })
+    resp.included = unique
   }
 }
 

From 6c8ac19ec26d533a5ace0a20e99ad8a23c2f5f71 Mon Sep 17 00:00:00 2001
From: Richard Walker <digitalsadhu@gmail.com>
Date: Sat, 10 Jun 2017 09:18:11 +0200
Subject: [PATCH 2/3] fix(serializer): switch let to var

---
 lib/serializer.js | 10 +++++-----
 1 file changed, 5 insertions(+), 5 deletions(-)

diff --git a/lib/serializer.js b/lib/serializer.js
index fe9ccfa..33b8155 100644
--- a/lib/serializer.js
+++ b/lib/serializer.js
@@ -380,18 +380,18 @@ function handleIncludes (resp, includes, relations, app) {
 
   if (embedded.length) {
     // This array may contain duplicate models if the same item is referenced multiple times in 'data'
-    let duplicate = _.flattenDeep(embedded)
+    var duplicate = _.flattenDeep(embedded)
     // So begin with an empty array that will only contain unique items
-    let unique = []
+    var unique = []
     // Iterate through each item in the first array
-    duplicate.forEach(function(d){
+    duplicate.forEach(function (d) {
       // Count the number of items in the unique array with matching 'type' AND 'id'
       // Since we're adhering to the JSONAPI spec, both 'type' and 'id' can assumed to be present
       // Both 'type' and 'id' are needed for comparison because we could theoretically have objects of different
       // types who happen to have the same 'id', and those would not be considered duplicates
-      let count = unique.filter(function(u){
+      var count = unique.filter(function (u) {
         return (u.type === d.type) && (u.id === d.id)
-      }).length;
+      }).length
       // If there are no matching entries, then add the item to the unique array
       if (count === 0) {
         unique.push(d)

From 4152a3a213a2ade166de81e49b9947ba13b786a0 Mon Sep 17 00:00:00 2001
From: Richard Walker <digitalsadhu@gmail.com>
Date: Sun, 11 Jun 2017 10:00:02 +0200
Subject: [PATCH 3/3] chore(tests): Add test for duplicate fix

---
 test/hasManyRelationships.test.js | 25 +++++++++++++++++++++++++
 1 file changed, 25 insertions(+)

diff --git a/test/hasManyRelationships.test.js b/test/hasManyRelationships.test.js
index 6549e78..2747ed7 100644
--- a/test/hasManyRelationships.test.js
+++ b/test/hasManyRelationships.test.js
@@ -113,4 +113,29 @@ describe('loopback json api hasMany relationships', function () {
         })
     })
   })
+
+  describe('Duplicate models in `includes`', function () {
+    beforeEach(function () {
+      const Foo = ds.createModel('foo', {title: String})
+      app.model(Foo)
+      const Bar = ds.createModel('bar', {title: String})
+      app.model(Bar)
+      Foo.hasMany(Bar)
+      Foo.belongsTo(Bar)
+
+      return Promise.all([
+        Foo.create({title: 'one', barId: 1}),
+        Bar.create({title: 'one', barId: 1, fooId: 1})
+      ])
+    })
+
+    it('should not occur', function () {
+      return request(app).get('/foos/1/?include=bars,bar')
+        .expect(200)
+        .then(function (res) {
+          expect(res.body.included.length).to.equal(1,
+            'Should be exactly 1 item in included array')
+        })
+    })
+  })
 })