upgrade/ss4-with-enforced-limit: added code snippets from separate pull request.

Author: MasseyIsaako

code/GridFieldConfig_LimitedRelationEditor.php

@@ -11,6 +11,12 @@
  * @since   2016-02-24
  */
 class GridFieldConfig_LimitedRelationEditor extends GridFieldConfig_RelationEditor {
+    /**
+     * used instance of the GridFieldLimitItems class.
+     *
+     * @var GridFieldLimitItems
+     */
+    protected $limiter;
 
     /**
      * Setup new configuration for a relation with a hard maximum limit of items.
@@ -25,7 +31,8 @@ public function __construct($maxItems) {
         $this->removeComponentsByType('GridFieldPageCount');
 
         // Setup GridFieldLimitItems.
-        $this->addComponent(new GridFieldLimitItems($maxItems));
+        $this->limiter = new GridFieldLimitItems($maxItems);
+        $this->addComponent($this->limiter);
     }
 
     /**
@@ -39,4 +46,16 @@ public function __construct($maxItems) {
     public function addComponent(GridFieldComponent $component, $insertBefore = 'GridFieldLimitItems') {
         return parent::addComponent($component, $insertBefore);
     }
+
+    /**
+     * allows you to enforce the set limit by removing options to add new items
+     *
+     * @return  GridFieldConfig_LimitedRelationEditor
+     */
+    public function enforceLimit()
+    {
+        // set the limit to be enforced
+        $this->limiter->enforceLimit();
+        return $this;
+    }
 }

code/GridFieldLimitItems.php

@@ -4,6 +4,8 @@
 
 use Psr\Cache\InvalidArgumentException;
 use SilverStripe\Forms\GridField\GridField;
+use SilverStripe\Forms\GridField\GridFieldAddExistingAutocompleter;
+use SilverStripe\Forms\GridField\GridFieldAddNewButton;
 use SilverStripe\Forms\GridField\GridField_DataManipulator;
 use SilverStripe\Forms\GridField\GridField_HTMLProvider;
 use SilverStripe\ORM\SS_List;
@@ -54,6 +56,15 @@ public function setMaxItems($maxItems) {
         $this->maxItems = (int) $maxItems;
     }
 
+    /**
+     * The maximum number of items you wish to allow in this grid field.
+     *
+     * @return int $maxItems
+     */
+    public function getMaxItems() {
+        return $this->maxItems;
+    }
+
     /**
      * Indicates that the 'Add New [x]' button should be removed once we reach our limit.
      *
@@ -95,6 +106,23 @@ public function setRemoveFromTop($removeFromTop) {
         return $this;
     }
 
+    /**
+     * allows you to enforce the set limit by removing options to add new items
+     */
+    public function enforceLimit()
+    {
+        // ensure we are removing the buttons if these are
+        $this->onAfterManipulate(function(GridField $grid, SS_List $list){
+            if ($list->count() == $this->getMaxItems()) {
+                // var_dump($grid->getConfig());
+                // die();
+
+                $grid->getConfig()->removeComponentsByType(GridFieldAddNewButton::class);
+                $grid->getConfig()->removeComponentsByType(GridFieldAddExistingAutocompleter::class);
+            }
+        });
+    }
+
     /**
      * Allows you to perform some sort of action BEFORE any sort of manipulation is performed.
      *
@@ -153,7 +181,7 @@ public function getManipulatedData(GridField $gridField, SS_List $dataList) {
         if(($dataList instanceof UnsavedRelationList)) return $dataList;
 
         // Not compatible with paginator.
-        if ($gridField->getConfig()->getComponentByType('GridFieldPaginator')) {
+        if ($gridField->getConfig()->getComponentByType(GridFieldPaginator::class)) {
             $this->debug('GridFieldLimitItems is not compatible with GridFieldPaginator.');
             return $dataList;
         }
@@ -188,7 +216,7 @@ public function getManipulatedData(GridField $gridField, SS_List $dataList) {
         if ($this->removeButton && $total >= $this->maxItems) {
             // ... obviously shouldn't be null, but just in case.
             $gridConfig = $gridField->getConfig();
-            if ($gridConfig) $gridConfig->removeComponentsByType('GridFieldAddNewButton');
+            if ($gridConfig) $gridConfig->removeComponentsByType(GridFieldAddNewButton::class);
         }
 
             // Allow custom action after manipulation.