From 0519b993979a8d5ff4d3870df8208567d67b6226 Mon Sep 17 00:00:00 2001
From: Travis Tidwell <travis@form.io>
Date: Fri, 2 Feb 2018 09:09:21 -0600
Subject: [PATCH] Adding an item comparer configuration to allow custom
 comparisons of items.

---
 README.md                     | 10 +++++++
 assets/scripts/src/choices.js |  5 +++-
 tests/spec/choices_spec.js    | 53 +++++++++++++++++++++++++++++++++++
 3 files changed, 67 insertions(+), 1 deletion(-)

diff --git a/README.md b/README.md
index 4689d4a..c7195f1 100644
--- a/README.md
+++ b/README.md
@@ -99,6 +99,9 @@ Or include Choices directly:
     maxItemText: (maxItemCount) => {
       return `Only ${maxItemCount} values can be added.`;
     },
+    itemComparer: (choice, item) => {
+      return choice === item;
+    },
     classNames: {
       containerOuter: 'choices',
       containerInner: 'choices__inner',
@@ -458,6 +461,13 @@ const example = new Choices(element, {
 
 **Usage:** The text that is shown when a user has focus on the input but has already reached the [max item count](https://github.com/jshjohnson/Choices#maxitemcount). To access the max item count, pass a function with a `maxItemCount` argument (see the [default config](https://github.com/jshjohnson/Choices#setup) for an example), otherwise pass a string.
 
+### itemComparer
+**Type:** `Function` **Default:** `strict equality`
+
+**Input types affected:** `select-one`, `select-multiple`
+
+**Usage:** Compare choice and value in appropriate way (e.g. deep equality for objects). To compare choice and value, pass a function with a `itemComparer` argument (see the [default config](https://github.com/jshjohnson/Choices#setup) for an example).
+
 ### classNames
 **Type:** `Object` **Default:**
 
diff --git a/assets/scripts/src/choices.js b/assets/scripts/src/choices.js
index a12dc05..42fc772 100644
--- a/assets/scripts/src/choices.js
+++ b/assets/scripts/src/choices.js
@@ -90,6 +90,9 @@ class Choices {
       maxItemText: (maxItemCount) => {
         return `Only ${maxItemCount} values can be added.`;
       },
+      itemComparer: (choice, item) => {
+        return choice === item;
+      },
       uniqueItemText: 'Only unique values can be added.',
       classNames: {
         containerOuter: 'choices',
@@ -947,7 +950,7 @@ class Choices {
       choiceValue.forEach((val) => {
         const foundChoice = choices.find((choice) => {
           // Check 'value' property exists and the choice isn't already selected
-          return choice.value === val;
+          return this.config.itemComparer(choice.value, val);
         });
 
         if (foundChoice) {
diff --git a/tests/spec/choices_spec.js b/tests/spec/choices_spec.js
index 778094f..3577669 100644
--- a/tests/spec/choices_spec.js
+++ b/tests/spec/choices_spec.js
@@ -78,6 +78,7 @@ describe('Choices', () => {
       expect(this.choices.config.noChoicesText).toEqual(jasmine.any(String));
       expect(this.choices.config.itemSelectText).toEqual(jasmine.any(String));
       expect(this.choices.config.classNames).toEqual(jasmine.any(Object));
+      expect(this.choices.config.itemComparer).toEqual(jasmine.any(Function));
       expect(this.choices.config.callbackOnInit).toEqual(null);
       expect(this.choices.config.callbackOnCreateTemplates).toEqual(null);
     });
@@ -1217,4 +1218,56 @@ describe('Choices', () => {
       expect(selectedItems[0].customProperties).toBe(expectedCustomProperties);
     });
   });
+
+  describe('should allow to use object in value', function() {
+    beforeEach(function() {
+      this.input = document.createElement('select');
+      this.input.className = 'js-choices';
+      this.input.setAttribute('multiple', '');
+
+      document.body.appendChild(this.input);
+
+      this.choicesArray = [
+        {
+          label: 'One',
+          value: {
+            id: 1
+          }
+        },
+        {
+          label: 'Two',
+          value: {
+            id: 2
+          }
+        },
+        {
+          label: 'Three',
+          value: {
+            id: 3
+          }
+        }
+      ];
+    });
+
+    afterEach(function() {
+      this.choices.destroy();
+    });
+
+    it('should allow the user to supply itemComparer via options', function() {
+      function comparer(choice, item) {
+        return choice.id === item.id;
+      }
+
+      this.choices = new Choices(this.input, {
+        itemComparer: comparer,
+        choices: this.choicesArray
+      });
+
+      this.choices.setValueByChoice({
+        id: 1
+      });
+
+      expect(this.choices.currentState.items[0].label).toBe(this.choicesArray[0].label);
+    });
+  });
 });