From 1e6ae4e3f9d0f4eff621f9d23578d21026f4cb0a Mon Sep 17 00:00:00 2001
From: Travis Tidwell <travis@form.io>
Date: Wed, 31 Jan 2018 20:15:15 -0600
Subject: [PATCH] Add ability to configure the item comparer function.

---
 README.md                    | 10 ++++++++++
 src/scripts/src/choices.js   |  2 +-
 src/scripts/src/constants.js |  1 +
 3 files changed, 12 insertions(+), 1 deletion(-)

diff --git a/README.md b/README.md
index 711efc3..48d5f2b 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/src/scripts/src/choices.js b/src/scripts/src/choices.js
index d40305d..64dafa6 100644
--- a/src/scripts/src/choices.js
+++ b/src/scripts/src/choices.js
@@ -2369,7 +2369,7 @@ class Choices {
   _findAndSelectChoiceByValue(val) {
     const choices = this.store.getChoices();
     // Check 'value' property exists and the choice isn't already selected
-    const foundChoice = choices.find(choice => choice.value === val);
+    const foundChoice = choices.find(choice => this.config.itemComparer(choice.value, val));
 
     if (foundChoice && !foundChoice.selected) {
       this._addItem(
diff --git a/src/scripts/src/constants.js b/src/scripts/src/constants.js
index 36070a8..5c377de 100644
--- a/src/scripts/src/constants.js
+++ b/src/scripts/src/constants.js
@@ -64,6 +64,7 @@ export const DEFAULT_CONFIG = {
   uniqueItemText: 'Only unique values can be added.',
   addItemText: value => `Press Enter to add <b>"${value}"</b>`,
   maxItemText: maxItemCount => `Only ${maxItemCount} values can be added.`,
+  itemComparer: (choice, item) => (choice === item),
   fuseOptions: {
     includeScore: true,
   },