Merge pull request #214 from bummzack/fix/has-one

fix: Deal with DataObjects or Int values

readme.md

@@ -73,6 +73,45 @@ $field = TagField::create(
 **Note:** This assumes you have imported the namespaces class, e.g. use
 SilverStripe\TagField\TagField;
 
+
+#### Has-One Relations
+
+You can also use the TagField to select values for `has_one` relations.
+Let's assume, that a `BlogPost` *has one* `BlogCategory`.
+
+```php
+class BlogCategory extends DataObject
+{
+    private static $db = [
+        'Title' => 'Varchar(200)',
+    ];
+}
+```
+
+```php
+use SilverStripe\ORM\DataObject;
+
+class BlogPost extends DataObject
+{
+    private static $has_one = [
+        'BlogCategory' => BlogCategory::class
+    ];
+}
+```
+
+```php
+$field = TagField::create(
+    'BlogCategoryID',
+    $this->fieldLabel('BlogCategory'),
+    BlogCategory::get()
+)
+    ->setIsMultiple(false)
+    ->setCanCreate(true);
+```
+
+**Note:** We're using the `ID` suffix for the field-name (eg. `BlogCategoryID` instead of `BlogCategory`) and
+only allow one value by setting `->setIsMultiple(false)`
+
 ### String Tags
 
 ```php

src/TagField.php

@@ -402,6 +402,14 @@ class TagField extends MultiSelectField
             return $values->column($this->getTitleField());
         }
 
+        if ($values instanceof DataObject && $values->exists()) {
+            return [$values->{$this->getTitleField()} ?? $values->ID];
+        }
+
+        if (is_int($values)) {
+            return [$values];
+        }
+
         return [trim((string) $values)];
     }