BUG Fix for $source left null

BUG Fix missing imports
Semver compatible setSource()

src/TagField.php

@@ -2,15 +2,18 @@
 
 namespace SilverStripe\TagField;
 
+use Exception;
 use SilverStripe\Control\Controller;
 use SilverStripe\Control\HTTPRequest;
 use SilverStripe\Control\HTTPResponse;
 use SilverStripe\Core\Injector\Injector;
 use SilverStripe\Forms\DropdownField;
+use SilverStripe\Forms\Validator;
 use SilverStripe\ORM\ArrayList;
 use SilverStripe\ORM\DataList;
 use SilverStripe\ORM\DataObject;
 use SilverStripe\ORM\DataObjectInterface;
+use SilverStripe\ORM\Relation;
 use SilverStripe\ORM\SS_List;
 use SilverStripe\View\ArrayData;
 use SilverStripe\View\Requirements;
@@ -67,11 +70,10 @@ class TagField extends DropdownField
      * @param null|DataList $value
      * @param string $titleField
      */
-    public function __construct($name, $title = '', $source = [], $value = null, $titleField = 'Title')
+    public function __construct($name, $title = '', $source = null, $value = null, $titleField = 'Title')
     {
-        $this->setSourceList($source);
         $this->setTitleField($titleField);
-        parent::__construct($name, $title, [], $value);
+        parent::__construct($name, $title, $source, $value);
     }
 
     /**
@@ -175,7 +177,9 @@ class TagField extends DropdownField
     }
 
     /**
-     * Get the DataList source. The 4.x upgrade for SelectField::setSource starts to convert this to an array
+     * Get the DataList source. The 4.x upgrade for SelectField::setSource starts to convert this to an array.
+     * If empty use getSource() for array version
+     *
      * @return DataList
      */
     public function getSourceList()
@@ -185,7 +189,8 @@ class TagField extends DropdownField
 
     /**
      * Set the model class name for tags
-     * @param  DataList $className
+     *
+     * @param DataList $sourceList
      * @return self
      */
     public function setSourceList($sourceList)
@@ -322,11 +327,29 @@ class TagField extends DropdownField
     public function getSource()
     {
         if (is_null($this->source)) {
-            $this->setSource($this->getSourceList());
+            $this->source = $this->getListMap($this->getSourceList());
         }
         return $this->source;
     }
 
+    /**
+     * Intercept DataList source
+     *
+     * @param mixed $source
+     * @return $this
+     */
+    public function setSource($source)
+    {
+        // When setting a datalist force internal list to null
+        if ($source instanceof DataList) {
+            $this->source = null;
+            $this->setSourceList($source);
+        } else {
+            parent::setSource($source);
+        }
+        return $this;
+    }
+
     /**
      * {@inheritdoc}
      */
@@ -342,7 +365,8 @@ class TagField extends DropdownField
     }
 
     /**
-     * {@inheritdoc}
+     * @param DataObject|DataObjectInterface $record DataObject to save data into
+     * @throws Exception
      */
     public function saveInto(DataObjectInterface $record)
     {
@@ -350,8 +374,9 @@ class TagField extends DropdownField
 
         $name = $this->getName();
         $titleField = $this->getTitleField();
-        $source = $this->getSource();
         $values = $this->Value();
+
+        /** @var Relation $relation */
         $relation = $record->$name();
         $ids = array();
 
@@ -384,13 +409,16 @@ class TagField extends DropdownField
      * Get or create tag with the given value
      *
      * @param  string $term
-     * @return DataObject
+     * @return DataObject|false
      */
     protected function getOrCreateTag($term)
     {
         // Check if existing record can be found
-        /** @var DataList $source */
         $source = $this->getSourceList();
+        if (!$source) {
+            return false;
+        }
+
         $titleField = $this->getTitleField();
         $record = $source
             ->filter($titleField, $term)
@@ -436,10 +464,10 @@ class TagField extends DropdownField
      */
     protected function getTags($term)
     {
-        /**
-         * @var array $source
-         */
         $source = $this->getSourceList();
+        if (!$source) {
+            return [];
+        }
 
         $titleField = $this->getTitleField();
 
@@ -476,10 +504,11 @@ class TagField extends DropdownField
     /**
      * Converts the field to a readonly variant.
      *
-     * @return TagField_Readonly
+     * @return ReadonlyTagField
      */
     public function performReadonlyTransformation()
     {
+        /** @var ReadonlyTagField $copy */
         $copy = $this->castedCopy(ReadonlyTagField::class);
         $copy->setSourceList($this->getSourceList());
         return $copy;