diff --git a/CHANGELOG.md b/CHANGELOG.md
index 4d4ba52..e795683 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -3,6 +3,21 @@ All notable changes to this project will be documented in this file.
 
 The format is based on [Keep a Changelog](http://keepachangelog.com/).
 
+## [Unreleased]
+
+## [1.8.1] - 2020-07-04
+### Fixed
+ - Fix `onlyCategories` option not applied correctly #135 (bjornhij)
+
+## [1.8.0] - 2019-08-25
+
+### Added
+ - Add `onlyCategories` option to Module settings #128
+
+### Changed
+ - Improve TranslateBehavior saving #99
+   The attribute is now saved as translation when the language of the application is different from the source language.
+
 ## [1.7.3] - 2018-04-04
 ### Fixed
  - Fix invalid column name in findOne() condition #118
@@ -80,11 +95,14 @@ The format is based on [Keep a Changelog](http://keepachangelog.com/).
  - Import/export feature #31
 
 ### Changed
- - Autocofus translation textarea in frontend translation dialog #33
+ - Autofocus translation textarea in frontend translation dialog #33
 
 ### Fixed
  - Round error in translation statistic
 
+[Unreleased]: https://github.com/lajax/yii2-translate-manager/compare/1.8.1...HEAD
+[1.8.1]: https://github.com/lajax/yii2-translate-manager/compare/1.8.0...1.8.1
+[1.8.0]: https://github.com/lajax/yii2-translate-manager/compare/1.7.3...1.8.0
 [1.7.3]: https://github.com/lajax/yii2-translate-manager/compare/1.7.2...1.7.3
 [1.7.2]: https://github.com/lajax/yii2-translate-manager/compare/1.7.1...1.7.2
 [1.7.1]: https://github.com/lajax/yii2-translate-manager/compare/1.7.0...1.7.1
diff --git a/Module.php b/Module.php
index 01dd20e..2138b49 100644
--- a/Module.php
+++ b/Module.php
@@ -3,6 +3,7 @@
 namespace lajax\translatemanager;
 
 use Yii;
+use yii\base\InvalidConfigException;
 use yii\web\ForbiddenHttpException;
 use yii\web\Response;
 
@@ -121,10 +122,15 @@ class Module extends \yii\base\Module
     public $roles = [];
 
     /**
-     * @var array list of the categories being ignored.
+     * @var string[] List of the categories being ignored.
      */
     public $ignoredCategories = [];
 
+    /**
+     * @var string[] List of the categories to be scanned. If empty, all categories will be scanned.
+     */
+    public $onlyCategories = [];
+
     /**
      * @var array directories/files being ignored.
      */
@@ -286,6 +292,18 @@ class Module extends \yii\base\Module
      */
     public $scanners = [];
 
+    /**
+     * @throws InvalidConfigException
+     */
+    public function init()
+    {
+        parent::init();
+
+        if ($this->onlyCategories && $this->ignoredCategories) {
+            throw new InvalidConfigException("Please configure either 'ignoredCategories', or 'onlyCategories'!");
+        }
+    }
+
     /**
      * @inheritdoc
      */
diff --git a/README.md b/README.md
index e68283a..c889899 100644
--- a/README.md
+++ b/README.md
@@ -111,6 +111,7 @@ A more complex example including database table with multilingual support is bel
         'jsTranslators' => ['lajax.t'], // list of the js function for translating messages.
         'patterns' => ['*.js', '*.php'],// list of file extensions that contain language elements.
         'ignoredCategories' => ['yii'], // these categories won't be included in the language database.
+        'onlyCategories' => ['yii'],    // only these categories will be included in the language database (cannot be used together with "ignoredCategories").
         'ignoredItems' => ['config'],   // these files will not be processed.
         'scanTimeLimit' => null,        // increase to prevent "Maximum execution time" errors, if null the default max_execution_time will be used
         'searchEmptyCommand' => '!',    // the search string to enter in the 'Translation' search field to find not yet translated items, set to null to disable this feature
@@ -420,7 +421,17 @@ class Category extends \yii\db\ActiveRecord {
 
 * With behavior (since 1.5.3):
 
-    **Note:** This will replace the model's original attribute values!
+    This behavior does the following:
+    - Replaces the specified attributes with translations after the model is loaded.
+    - Saves the attribute values as:
+        1. Source messages, if the current language is the source language.
+        2. Translations, if the current language is different from the source language.
+           This way the value stored in database is not overwritten with the translation.
+
+    **Note**: If the model should be saved as translation, but the source message does not exist yet in the database
+    then the message is saved as the source message whether the current language is the source language or not.
+    To avoid this scan the database for existing messages when using the behavior first, and only save new records
+    when the current language is the source language.
 
 ```php
 namespace common\models;
diff --git a/behaviors/TranslateBehavior.php b/behaviors/TranslateBehavior.php
index 0e298a7..7b21310 100644
--- a/behaviors/TranslateBehavior.php
+++ b/behaviors/TranslateBehavior.php
@@ -6,9 +6,23 @@
 use yii\db\BaseActiveRecord;
 use yii\behaviors\AttributeBehavior;
 use lajax\translatemanager\helpers\Language;
+use lajax\translatemanager\models\LanguageSource;
+use lajax\translatemanager\models\LanguageTranslate;
 
 /**
- * TranslateManager Database translate behavior.
+ * Behavior that translates the model attributes, and saves the changes into database.
+ *
+ * This behavior does the following:
+ *  - Replaces the specified attributes with translations after the model is loaded.
+ *  - Saves the attribute values as:
+ *      1. Source messages, if the current language is the source language.
+ *      2. Translations, if the current language is different from the source language.
+ *         This way the value stored in database is not overwritten with the translation.
+ *
+ * **Note**: If the model should be saved as translation, but the source message does not exist yet in the database
+ * then the message is saved as the source message whether the current language is the source language or not.
+ * To avoid this scan the database for existing messages when using the behavior first, and only save new records
+ * when the current language is the source language.
  *
  * Installation:
  *
@@ -45,6 +59,11 @@ class TranslateBehavior extends AttributeBehavior
      */
     public $category = 'database';
 
+    /**
+     * @var BaseActiveRecord the owner model of this behavior
+     */
+    public $owner;
+
     /**
      * @inheritdoc
      */
@@ -68,31 +87,88 @@ public function events()
     }
 
     /**
-     * Translates a message to the specified language.
+     * Translates the attributes to the current language.
      *
      * @param \yii\base\Event $event
      */
     public function translateAttributes($event)
     {
-        /* @var $owner BaseActiveRecord */
-        $owner = $this->owner;
         foreach ($this->translateAttributes as $attribute) {
-            $owner->{$attribute} = Yii::t($this->category, $owner->attributes[$attribute]);
+            $this->owner->{$attribute} = Yii::t($this->category, $this->owner->attributes[$attribute]);
         }
     }
 
     /**
-     * Saveing new language element by category.
+     * Saves new language element by category.
      *
      * @param \yii\base\Event $event
      */
     public function saveAttributes($event)
     {
-        /* @var $owner BaseActiveRecord */
-        $owner = $this->owner;
+        $isAppInSourceLanguage = Yii::$app->sourceLanguage === Yii::$app->language;
+
         foreach ($this->translateAttributes as $attribute) {
-            if ($owner->isAttributeChanged($attribute)) {
-                Language::saveMessage($owner->attributes[$attribute], $this->category);
+            if (!$this->owner->isAttributeChanged($attribute)) {
+                continue;
+            }
+
+            if ($isAppInSourceLanguage || !$this->saveAttributeValueAsTranslation($attribute)) {
+                Language::saveMessage($this->owner->attributes[$attribute], $this->category);
+            }
+        }
+    }
+
+    /**
+     * @param string $attribute The name of the attribute.
+     *
+     * @return bool Whether the translation is saved.
+     */
+    private function saveAttributeValueAsTranslation($attribute)
+    {
+        $sourceMessage = $this->owner->getOldAttribute($attribute);
+        $translatedMessage = $this->owner->attributes[$attribute];
+
+        // Restore the original value, so it won't be replaced with the translation in the database.
+        $this->owner->{$attribute} = $sourceMessage;
+
+        $translateSource = $this->findSourceMessage($sourceMessage);
+        if (!$translateSource) {
+            return false; // The source does not exist, the message cannot be saved as translation.
+        }
+
+        $translation = new LanguageTranslate();
+        foreach ($translateSource->languageTranslates as $tmpTranslate) {
+            if ($tmpTranslate->language === Yii::$app->language) {
+                $translation = $tmpTranslate;
+                break;
+            }
+        }
+
+        if ($translation->isNewRecord) {
+            $translation->id = $translateSource->id;
+            $translation->language = Yii::$app->language;
+        }
+
+        $translation->translation = $translatedMessage;
+        $translation->save();
+
+        return true;
+    }
+
+    /**
+     * Finds the source record with case sensitive match.
+     *
+     * @param string $message
+     *
+     * @return LanguageSource|null Null if the source is not found.
+     */
+    private function findSourceMessage($message)
+    {
+        $sourceMessages = LanguageSource::findAll(['message' => $message, 'category' => $this->category]);
+
+        foreach ($sourceMessages as $source) {
+            if ($source->message === $message) {
+                return $source;
             }
         }
     }
diff --git a/composer.json b/composer.json
index 94a0684..a37bf68 100644
--- a/composer.json
+++ b/composer.json
@@ -1,6 +1,6 @@
 {
     "name": "lajax/yii2-translate-manager",
-    "description": "Online Translate",
+    "description": "Translation management extension for Yii 2",
     "type": "yii2-extension",
     "keywords": ["yii2", "extension", "translate", "language", "module"],
     "license": "MIT",
diff --git a/services/scanners/ScannerFile.php b/services/scanners/ScannerFile.php
index 83e4867..083657e 100644
--- a/services/scanners/ScannerFile.php
+++ b/services/scanners/ScannerFile.php
@@ -269,6 +269,14 @@ private function _getRoots()
      */
     protected function isValidCategory($category)
     {
-        return !in_array($category, $this->module->ignoredCategories);
+        if ($this->module->onlyCategories) {
+            return in_array($category, $this->module->onlyCategories);
+        }
+
+        if ($this->module->ignoredCategories) {
+            return !in_array($category, $this->module->ignoredCategories);
+        }
+
+        return true;
     }
 }