Issue 3357 - Add GridField Readonly Transformation

GridField doesn't have a valid readonly state if it's value is set to an Object
without `forTemplate()`. The default behaviour is to render a ReadonlyField,
but given GridField is a complex type this isn't suitable.

This bugfix provides a transformation method to render only components that are
whitelisted to provide a readonly state.

@see #3357 - https://github.com/silverstripe/silverstripe-framework/issues/3357

src/Forms/GridField/GridField.php

@@ -105,6 +105,21 @@ class GridField extends FormField
      */
     protected $name = '';
 
+    /**
+     * A whitelist of readonly component classes allowed if performReadonlyTransform is called.
+     *
+     * @var array
+     */
+    protected $readonlyComponents = array(
+        GridFieldDetailForm::class,
+        GridFieldDataColumns::class,
+        GridFieldConfig_RecordViewer::class,
+        GridFieldToolbarHeader::class,
+        GridFieldPageCount::class,
+        GridFieldPaginator::class,
+        GridState_Component::class
+    );
+
     /**
      * Pattern used for looking up
      */
@@ -193,6 +208,60 @@ class GridField extends FormField
         );
     }
 
+    /**
+     * Overload the readonly components for this gridfield.
+     *
+     * @param array $components an array map of component class references to whitelist for a readonly version.
+     */
+    public function setReadonlyComponents(array $components)
+    {
+        $this->readonlyComponents = $components;
+    }
+
+    /**
+     * Return the readonly components
+     *
+     * @return array a map of component classes.
+     */
+    public function getReadonlyComponents()
+    {
+        return $this->readonlyComponents;
+    }
+
+    /**
+     * Custom Readonly transformation to remove actions which shouldn't be present for a readonly state.
+     *
+     * @return GridField
+     */
+    public function performReadonlyTransformation()
+    {
+        $copy = clone $this;
+        $copy->setReadonly(true);
+
+        // get the whitelist for allowable readonly components
+        $allowedComponents = $this->getReadonlyComponents();
+        foreach ($this->getConfig()->getComponents() as $component) {
+
+            // if a component doesn't exist, remove it from the readonly version.
+            if (!in_array(get_class($component), $allowedComponents)) {
+                $copy->getConfig()->removeComponent($component);
+            }
+        }
+
+        return $copy;
+    }
+
+    /**
+     * Disabling the gridfield should have the same affect as making it readonly (removing all action items).
+     *
+     * @return GridField
+     */
+    public function performDisabledTransformation(){
+        parent::performDisabledTransformation();
+
+        return $this->performReadonlyTransformation();
+    }
+
     /**
      * @return GridFieldConfig
      */

tests/php/Forms/GridField/GridFieldReadonlyTest.php

@@ -0,0 +1,87 @@
+<?php
+
+namespace SilverStripe\Forms\Tests\GridField;
+
+use SilverStripe\Forms\GridField\GridField_ActionMenu;
+use SilverStripe\Forms\GridField\GridFieldAddExistingAutocompleter;
+use SilverStripe\Forms\GridField\GridFieldAddNewButton;
+use SilverStripe\Forms\GridField\GridFieldButtonRow;
+use SilverStripe\Forms\GridField\GridFieldConfig_RelationEditor;
+use SilverStripe\Forms\GridField\GridFieldDataColumns;
+use SilverStripe\Forms\GridField\GridFieldDeleteAction;
+use SilverStripe\Forms\GridField\GridFieldDetailForm;
+use SilverStripe\Forms\GridField\GridFieldEditButton;
+use SilverStripe\Forms\GridField\GridFieldFilterHeader;
+use SilverStripe\Forms\GridField\GridFieldPageCount;
+use SilverStripe\Forms\GridField\GridFieldPaginator;
+use SilverStripe\Forms\GridField\GridFieldSortableHeader;
+use SilverStripe\Forms\GridField\GridFieldToolbarHeader;
+use SilverStripe\Forms\Tests\GridField\GridFieldTest\Cheerleader;
+use SilverStripe\Forms\Tests\GridField\GridFieldTest\Team;
+use SilverStripe\Dev\SapphireTest;
+use SilverStripe\Forms\GridField\GridField;
+use SilverStripe\Versioned\VersionedGridFieldState\VersionedGridFieldState;
+
+class GridFieldReadonlyTest extends SapphireTest
+{
+    protected static $fixture_file = 'GridFieldReadonlyTest.yml';
+
+    protected static $extra_dataobjects = array(
+        Team::class,
+        Cheerleader::class,
+    );
+
+    /**
+     * The CMS can set the value of a GridField to be a hasMany relation, which needs a readonly state.
+     * This test ensures GridField has a readonly transformation.
+     */
+    public function testReadOnlyTransformation()
+    {
+        // Build a hasMany Relation via getComponents like ModelAdmin does.
+        $components = Team::get_one(Team::class)
+            ->getComponents('Cheerleaders');
+
+        $gridConfig = GridFieldConfig_RelationEditor::create();
+
+        // Build some commonly used components to make sure we're only allowing the correct components
+        $gridConfig->addComponent(new GridFieldButtonRow('before'));
+        $gridConfig->addComponent(new GridFieldAddNewButton('buttons-before-left'));
+        $gridConfig->addComponent(new GridFieldAddExistingAutocompleter('buttons-before-right'));
+        $gridConfig->addComponent(new GridFieldToolbarHeader());
+        $gridConfig->addComponent($sort = new GridFieldSortableHeader());
+        $gridConfig->addComponent($filter = new GridFieldFilterHeader());
+        $gridConfig->addComponent(new GridFieldDataColumns());
+        $gridConfig->addComponent(new GridFieldEditButton());
+        $gridConfig->addComponent(new GridFieldDeleteAction(true));
+        $gridConfig->addComponent(new GridField_ActionMenu());
+        $gridConfig->addComponent(new GridFieldPageCount('toolbar-header-right'));
+        $gridConfig->addComponent($pagination = new GridFieldPaginator(2));
+        $gridConfig->addComponent(new GridFieldDetailForm());
+        $gridConfig->addComponent(new GridFieldDeleteAction());
+        $gridConfig->addComponent(new VersionedGridFieldState());
+
+        $gridField = GridField::create(
+            'Cheerleaders',
+            'Cheerleaders',
+            $components,
+            $gridConfig
+        );
+
+        // Model Admin sets the value of the GridField directly to the relation, which doesn't have a forTemplate()
+        // function, if we rely on FormField to render into a ReadonlyField we'll get an error as HasManyRelation
+        // doesn't have a forTemplate() function.
+        $gridField->setValue($components);
+        $gridField->setModelClass(Cheerleader::class);
+
+        // This function is called by $form->makeReadonly().
+        $readonlyGridField = $gridField->performReadonlyTransformation();
+
+        // if we've made it this far, then the GridField is at least transforming correctly.
+        $readonlyComponents = $readonlyGridField->getReadonlyComponents();
+
+        // assert that all the components in the readonly version are present in the whitelist.
+        foreach($readonlyGridField->getConfig()->getComponents() as $component){
+            $this->assertTrue(in_array(get_class($component), $readonlyComponents));
+        }
+    }
+}

tests/php/Forms/GridField/GridFieldReadonlyTest.yml

@@ -0,0 +1,27 @@
+SilverStripe\Forms\Tests\GridField\GridFieldTest\Team:
+  team1:
+    Name: Team 1
+    City: Cologne
+  team2:
+    Name: Team 2
+    City: Wellington
+  team3:
+    Name: Team 3
+    City: Auckland
+  team4:
+    Name: Team 4
+    City: Melbourne
+
+SilverStripe\Forms\Tests\GridField\GridFieldTest\Cheerleader:
+  cheerleader1:
+    Name: Heather
+    Team: =>SilverStripe\Forms\Tests\GridField\GridFieldTest\Team.team1
+  cheerleader2:
+    Name: Bob
+    Team: =>SilverStripe\Forms\Tests\GridField\GridFieldTest\Team.team1
+  cheerleader3:
+    Name: Jenny
+    Team: =>SilverStripe\Forms\Tests\GridField\GridFieldTest\Team.team1
+  cheerleader4:
+    Name: Sam
+    Team: =>SilverStripe\Forms\Tests\GridField\GridFieldTest\Team.team1