Fixed default message formatter (closes #41)

README.md

@@ -180,17 +180,35 @@ The `errors` attribute contains a list of all original values that failed the un
 
 ### Error messages
 
-By default, the `ValidatorError` message will be the formatted value of `mongoose.Error.messages.general.unique` (which is set automatically by this package if not already defined).
+By default, the `ValidatorError` message will be the formatted value of a String `options.message` (which is set automatically by this package if not already defined).
 
-The default value of `mongoose.Error.messages.general.unique` is ``"Path `{PATH}` ({VALUE}) is not unique."`` which adheres to [the Mongoose error message defaults](https://github.com/Automattic/mongoose/blob/master/lib/error/messages.js).
+The default value of `options.message` is ``"Path `{PATH}` ({VALUE}) is not unique."`` which adheres to [the Mongoose error message defaults](https://github.com/Automattic/mongoose/blob/master/lib/error/messages.js).
 
-If you want to override it, add your custom message in the `unique` field (instead of `true`), during the schema's creation (or) override the default global Mongoose error:
+If you want to override it, you have two choices:
+
+1. Add your custom message in the `unique` field (instead of `true`), during the schema's creation:
+
+```diff
+const userSchema = mongoose.Schema({
+    name: {
+        type: String,
++        unique: 'Two users cannot share the same username ({VALUE})'
+-        unique: true
+    }
+});
+```
+
+2. Override the global default through `options.message` while initializing the schema plugin:
 
 ```js
 // change this however you'd like
-mongoose.Error.messages.general.unique = 'Path `{PATH}` ({VALUE}) is not unique.';
+userSchema.plugin(beautifyUnique, {
+    message: "Path `{PATH}` ({VALUE}) is not unique."
+});
 ```
 
+> **Note**: Custom messages defined in the schema will always take precedence over the global default message.
+
 ## Contributions
 
 This is free and open source software. All contributions (even small ones) are welcome. [Check out the contribution guide to get started!](CONTRIBUTING.md)

index.js

@@ -2,12 +2,6 @@
 
 var mongoose = require('mongoose');
 
-// Bind custom message for mongoose if it doesn't already exist
-if (mongoose.Error.messages.general.unique === undefined) {
-    mongoose.Error.messages.general.unique =
-        'Path `{PATH}` ({VALUE}) is not unique.';
-}
-
 var errorRegex = /index:\s*(?:.+?\.\$)?(.*?)\s*dup/;
 var indexesCache = {};
 
@@ -56,9 +50,10 @@ function getIndexes(collection) {
  * @param {Collection} collection Mongoose collection.
  * @param {Object} values Hashmap containing data about duplicated values
  * @param {Object} messages Map fields to unique error messages
+ * @param {String} message Default message formatter string
  * @return {Promise.<ValidationError>} Beautified error message
  */
-function beautify(error, collection, values, messages) {
+function beautify(error, collection, values, messages, message) {
     // Try to recover the list of duplicated fields
     var onSuberrors = global.Promise.resolve({});
 
@@ -86,7 +81,7 @@ function beautify(error, collection, values, messages) {
                     if (typeof messages[path] === 'string') {
                         props.message = messages[path];
                     } else {
-                        props.message = mongoose.Error.messages.general.unique;
+                        props.message = message;
                     }
 
                     suberrors[path] = new mongoose.Error.ValidatorError(props);
@@ -105,9 +100,14 @@ function beautify(error, collection, values, messages) {
     });
 }
 
-module.exports = function (schema) {
+module.exports = function (schema, options) {
     var tree = schema.tree, key, messages = {};
 
+    options = options || {};
+    if (!options.message) {
+        options.message = 'Path `{PATH}` ({VALUE}) is not unique.';
+    }
+
     // Fetch error messages defined in the "unique" field,
     // store them for later use and replace them with true
     for (key in tree) {
@@ -161,7 +161,7 @@ module.exports = function (schema) {
                 values = doc;
             }
 
-            beautify(error, collection, values, messages)
+            beautify(error, collection, values, messages, options.message)
                 .then(next)
                 .catch(function (beautifyError) {
                     setTimeout(function () {