BUG Fix decimal scaffolding

Fixes #7454

src/ORM/FieldType/DBDecimal.php

@@ -11,7 +11,26 @@ use SilverStripe\Forms\NumericField;
 class DBDecimal extends DBField
 {
 
-    protected $wholeSize, $decimalSize, $defaultValue;
+    /**
+     * Whole number size
+     *
+     * @var int
+     */
+    protected $wholeSize = 9;
+
+    /**
+     * Decimal scale
+     *
+     * @var int
+     */
+    protected $decimalSize = 2;
+
+    /**
+     * Default value
+     *
+     * @var string
+     */
+    protected $defaultValue = 0;
 
     /**
      * Create a new Decimal field.
@@ -27,7 +46,6 @@ class DBDecimal extends DBField
         $this->decimalSize = is_int($decimalSize) ? $decimalSize : 2;
 
         $this->defaultValue = number_format((float) $defaultValue, $decimalSize);
-        ;
 
         parent::__construct($name);
     }
@@ -84,7 +102,8 @@ class DBDecimal extends DBField
      */
     public function scaffoldFormField($title = null, $params = null)
     {
-        return new NumericField($this->name, $title);
+        return NumericField::create($this->name, $title)
+            ->setScale($this->decimalSize);
     }
 
     /**

tests/php/ORM/DecimalTest.php

@@ -3,12 +3,16 @@
 namespace SilverStripe\ORM\Tests;
 
 use SilverStripe\Dev\SapphireTest;
+use SilverStripe\ORM\FieldType\DBDecimal;
 
 class DecimalTest extends SapphireTest
 {
 
     protected static $fixture_file = 'DecimalTest.yml';
 
+    /**
+     * @var DecimalTest\TestObject
+     */
     protected $testDataObject;
 
     protected static $extra_dataobjects = array(
@@ -56,4 +60,15 @@ class DecimalTest extends SapphireTest
             'Default value for Decimal type is set to 4'
         );
     }
+
+    public function testScaffoldFormField()
+    {
+        /** @var DBDecimal $decimal */
+        $decimal = $this->testDataObject->dbObject('MyDecimal2');
+        $field = $decimal->scaffoldFormField('The Decimal');
+        $this->assertEquals(3, $field->getScale());
+        $field->setValue(1.9999);
+        $this->assertEquals(1.9999, $field->dataValue());
+        $this->assertEquals('2.000', $field->Value());
+    }
 }