CMSEditLink method modified to support DataObject links and Example o…

…f using ElemenatalArea with DataObject

docs/en/examples/elementalarea_with_dataobject.md

@@ -0,0 +1,111 @@
+# Using ElementalArea with DataObject
+
+## Creating Model and adding ElementalArea
+
+In this example the class `BlogPost` will be created, it will extend the `DataObject` class. Also a new `BlogPost` Admin section will be created in the Admin panel where CMS users can manage the `BlogPost` objects.
+
+Let's look at an example:
+
+**app/src/Admins/BlogPostsAdmin.php**
+
+```php
+<?php
+
+namespace App\Admins;
+
+use App\Models\BlogPost;
+use SilverStripe\Admin\ModelAdmin;
+
+class BlogPostsAdmin extends ModelAdmin
+{
+    private static string $url_segment = 'blog-posts-admin';
+
+    private static string $menu_title = 'Blog Posts';
+
+    private static string $menu_icon_class = 'font-icon-block-banner';
+
+    private static array $managed_models = [
+        BlogPost::class,
+    ];
+}
+```
+
+`$managed_models` - this static variable connects `BlogPostAdmin` with `BlogPost`, which will be created in the following code.\
+When you create a `DataObject` you should define the connection between your `DataObject` and `ElementalArea` by adding `$has_one` relationship.\
+In this example `BlogPost` will have one `ElementalArea`.
+
+**app/src/Models/BlogPost.php**
+
+```php
+<?php
+
+namespace App\Models;
+
+use App\Admins\BlogPostsAdmin;
+use DNADesign\Elemental\Models\ElementalArea;
+use SilverStripe\Control\Controller;
+use SilverStripe\ORM\DataObject;
+use SilverStripe\Versioned\Versioned;
+
+class BlogPost extends DataObject
+{
+    private static string $table_name = 'BlogPost';
+
+    private static $has_one = [
+        'ElementalArea' => ElementalArea::class,
+    ];
+
+    private static $owns = ['ElementalArea'];
+
+    // ...
+}
+ ```
+
+If you are using `ElementalArea` together with `DataObject`, it is important to define the `CMSEditLink()` method in the class.\
+`BaseElement::CMSEditLink()` relies on a valid CMS link being available in the parent `DataObject` - in this case, `BlogPost`. It is used to navigate directly to the editing section of the particular element.\
+***Note:*** For nested `GridField`s this method can get more complicated. Similarly, if your class is used in multiple admins, you will have to choose one to be the canonical admin section for the purposes of this method. This example only shows the simplest case, where the `BlogPost` class is used directly in `BlogPostsAdmin`.
+
+```php
+// ...
+
+class BlogPost extends DataObject
+{
+    // ...
+
+    public function CMSEditLink()
+    {
+        // In this example we use BlogPostsAdmin class as Controller
+        $admin = BlogPostsAdmin::singleton();
+
+        // Makes link more readable. Instead App\Models\ BlogPost, we get App-Models-BlogPost
+        $sanitisedClassname = str_replace('\\', '-', $this->ClassName);
+
+        // Returns link to editing section with elements
+        return Controller::join_links(
+            $admin->Link($sanitisedClassname),
+            'EditForm/field/',
+            $sanitisedClassname,
+            'item',
+            $this->ID,
+        );
+    }
+
+    // ...
+}
+
+```
+
+And finally, add `ElementalAreasExtension` to the `DataObject`
+
+**app/_config/elemental.yml**
+
+```yml
+App\Models\BlogPost:
+  extensions: 
+    - DNADesign\Elemental\Extensions\ElementalAreasExtension
+```
+
+## Related Documentation
+
+* [Preview](https://docs.silverstripe.org/en/4/developer_guides/customising_the_admin_interface/preview/)
+(note that this requires at least `silverstripe/admin` 4.11.0 and `dnadesign/silverstripe-elemental` 4.9.0)

src/Models/BaseElement.php

@@ -243,13 +243,18 @@ public function canEdit($member = null)
     public function canDelete($member = null)
     {
         $extended = $this->extendedCan(__FUNCTION__, $member);
+
         if ($extended !== null) {
             return $extended;
         }
 
         if ($this->hasMethod('getPage')) {
             if ($page = $this->getPage()) {
-                return $page->canArchive($member);
+                if ($page->hasExtension(Versioned::class)) {
+                    return $page->canArchive($member);
+                } else {
+                    return $page->canDelete($member);
+                }
             }
         }
 
@@ -568,7 +573,8 @@ public function getSimpleClassName()
     }
 
     /**
-     * @return null|SiteTree
+     * Despite the name of the method, getPage can return any type of DataObject
+     * @return null|DataObject
      * @throws \Psr\Container\NotFoundExceptionInterface
      * @throws \SilverStripe\ORM\ValidationException
      */
@@ -579,7 +585,6 @@ public function getPage()
             return $this->cacheData['page'];
         }
 
-
         $class = DataObject::getSchema()->hasOneComponent($this, 'Parent');
         $area = ($this->ParentID) ? DataObject::get_by_id($class, $this->ParentID) : null;
         if ($area instanceof ElementalArea && $area->exists()) {
@@ -638,9 +643,10 @@ public function getAnchor()
      */
     public function AbsoluteLink($action = null)
     {
-        if ($page = $this->getPage()) {
+        $page = $this->getPage();
+
+        if ($page && ClassInfo::hasMethod($page, 'AbsoluteLink')) {
             $link = $page->AbsoluteLink($action) . '#' . $this->getAnchor();
-
             $this->extend('updateAbsoluteLink', $link);
 
             return $link;
@@ -657,9 +663,10 @@ public function AbsoluteLink($action = null)
      */
     public function Link($action = null)
     {
-        if ($page = $this->getPage()) {
-            $link = $page->Link($action) . '#' . $this->getAnchor();
+        $page = $this->getPage();
 
+        if ($page && ClassInfo::hasMethod($page, 'Link')) {
+            $link = $page->Link($action) . '#' . $this->getAnchor();
             $this->extend('updateLink', $link);
 
             return $link;
@@ -712,35 +719,62 @@ public function CMSEditLink($directLink = false)
             return $this->cacheData['cms_edit_link'];
         }
 
+        $link = $this->getElementCMSLink($directLink);
+        $this->extend('updateCMSEditLink', $link);
+
+        if ($link) {
+            $this->cacheData['cms_edit_link'] = $link;
+        }
+
+        return $link;
+    }
+
+    /**
+     * @param bool $directLink
+     * @return null|string
+     */
+    private function getElementCMSLink(bool $directLink)
+    {
         $relationName = $this->getAreaRelationName();
         $page = $this->getPage();
 
+        $link = null;
+
         if (!$page) {
-            $link = null;
-            $this->extend('updateCMSEditLink', $link);
             return $link;
         }
 
-        if (!$page instanceof SiteTree && method_exists($page, 'CMSEditLink')) {
-            $link = Controller::join_links($page->CMSEditLink(), 'ItemEditForm');
-        } else {
+        if ($page instanceof SiteTree) {
             $link = $page->CMSEditLink();
+        } elseif (ClassInfo::hasMethod($page, 'CMSEditLink')) {
+            $link = Controller::join_links($page->CMSEditLink(), 'ItemEditForm');
         }
-
-        // In-line editable blocks should just take you to the page. Editable ones should add the suffix for detail form
+        // In-line editable blocks should just take you to the page.
+        // Editable ones should add the suffix for detail form.
         if (!$this->inlineEditable() || $directLink) {
-            $link = Controller::join_links(
-                singleton(CMSPageEditController::class)->Link('EditForm'),
-                $page->ID,
-                'field/' . $relationName . '/item/',
-                $this->ID,
-                'edit'
-            );
+            if ($page instanceof SiteTree) {
+                return Controller::join_links(
+                    singleton(CMSPageEditController::class)->Link('EditForm'),
+                    $page->ID,
+                    'field',
+                    $relationName,
+                    'item',
+                    $this->ID,
+                    'edit'
+                );
+            } else {
+                // If $page is not a Page, then generate $link base on $page->CMSEditLink()
+                return Controller::join_links(
+                    $link,
+                    'field',
+                    $relationName,
+                    'item',
+                    $this->ID,
+                    'edit'
+                );
+            }
         }
 
-        $this->extend('updateCMSEditLink', $link);
-
-        $this->cacheData['cms_edit_link'] = $link;
         return $link;
     }