fix(ModelAdmin): Workaround for silverstripe-recipe 4.3.0

- Primary takeaway: this allows a site to use multisites with
  silverstripe-recipe 4.3.0
- Silverstripe-recipe 4.3.0 introduced changes that broke the previous
  approach to retrieving the model class.
- This will be fixed in silverstripe-recipe 4.3.1 (really
  silverstripe-admin 1.3.1).
- Don't want to require a specific version of ss-admin as it will create
  composer conflicts.
- This commit changes multisites to only work with ss-recipe >= 4.3.0
- When using ss-recipe 4.3.0:
  - An error will be thrown if you use the MultisitesAware extension.
  - Else MultisitesAware will be bypassed.
- Will work with ss-recipe >= 4.3.1 (other potential issues aside).

composer.json

@@ -13,6 +13,7 @@
 	"require":
 	{
 		"silverstripe/cms": "~4.0",
+		"silverstripe/admin": "^4.3",
 		"symbiote/silverstripe-multivaluefield": "~5.0"
 	},
     "require-dev": {
@@ -24,7 +25,7 @@
         ],
 		"installer-name": "multisites",
 		"branch-alias": {
-			"dev-master": "5.0.x-dev"
+			"dev-master": "5.2.x-dev"
 		}
 	},
 	"replace": {

src/Admin/MultisitesModelAdminExtension.php

@@ -9,14 +9,15 @@
 use SilverStripe\Core\Extension;
 use Symbiote\Multisites\Multisites;
 use Symbiote\Multisites\Model\Site;
+use Symbiote\Multisites\Extension\MultisitesAware;
 
 /**
  * MultisitesModelAdminExtension
  *
  * @package silverstripe-multisites
  */
 class MultisitesModelAdminExtension extends Extension {
-	
+
 	private static $allowed_actions = array(
 		'updateSiteFilter'
 	);
@@ -27,24 +28,26 @@ class MultisitesModelAdminExtension extends Extension {
 	 * @var DataObject
 	 **/
 	private $listDataClass;
-	
+
 	/**
 	 * If this dataClass is MultisitesAware, set the Multisites_ActiveSite 
 	 * session variable to one of the follwing:
 	 * a) The SiteID passed in the request params, if it exists
 	 * b) The current site, if the current member is a manager of that site
 	 * c) The first site that the current member is a manager of
 	 **/
-	public function onAfterInit(){	
-		if($this->modelIsMultiSitesAware()) {
+	public function onAfterInit(){
+        // throws exception if using ss-recipe <= 4.3.0 and using MultiSitesAware
+		$this->checkMultisitesAware();
 
+		if($this->modelIsMultiSitesAware()) {
 			if($siteID = $this->owner->getRequest()->requestVar('SiteID')){
 				$this->setActiveSite($siteID);
 			}
 
 			if(!$this->getActiveSite()){
 				$managedByMember = Multisites::inst()->sitesManagedByMember();
-				
+
 				if(count($managedByMember)){
 					$currentSiteID = Multisites::inst()->getCurrentSiteId();
 					if(in_array($currentSiteID, $managedByMember)){
@@ -58,7 +61,27 @@ public function onAfterInit(){
 		}
 	}
 
-
+	/**
+     * Prevents use of MultisitesAware extension when using
+     * silvestripe-recipe <= 4.3.0
+     *
+     * @return void
+     */
+    public function checkMultisitesAware() {
+        // only true if using silverstripe-recipe <= 4.3.0
+        if (!$this->owner->hasMethod('getModelClass')) {
+            $models = $this->owner->getManagedModels();
+            // throw error if any models use MultisitesAware extension
+            foreach ($models as $model => $val) {
+                if($model::has_extension(MultisitesAware::class)) {
+                    throw new \Exception(
+                        '`ModelAdmin::getModelClass()` missing. You are likely using `silverstripe-recipe:4.3.0` which introduced this bug. This can be fixed by updating to `silverstripe-recipe:4.3.1` or greater.'
+                    );
+                }
+            }
+        }
+    }
+
 	/**
 	 * If this dataClass is MultisitesAware, filter the list by the current Multisites_ActiveSite
 	 **/
@@ -71,7 +94,6 @@ public function updateList(&$list){
 		}
 	}
 
-
 	/**
 	 * If the current member is not a "Manager" of any sites, they shouldn't be able to manage MultisitesAware DataObjects.
 	 **/
@@ -88,7 +110,6 @@ public function updateEditForm($form){
 		}
 	}
 
-
 	/**
 	 * Provide a Site filter
 	 **/
@@ -110,7 +131,6 @@ public function updateSearchForm($form){
 		}
 	}
 
-
 	/**
 	 * get the active site for this model admin
 	 *
@@ -128,7 +148,6 @@ public function getActiveSite() {
 		}
 	}
 
-
 	/**
 	 * Set the active site for this model admin
 	 *
@@ -143,7 +162,6 @@ public function setActiveSite($siteID) {
 		}
 	}
 
-
 	/**
 	 * Get the key used to store this model admin active site Session to
 	 *
@@ -153,27 +171,47 @@ public function getActiveSiteSessionKey() {
 		return 'Multisites_ActiveSite_For_' . get_class($this->owner);
 	}
 
-
-	/**
-	 * Get and cache an instance of the data class currently being listed
-	 *
-	 * @return DataObject
-	 **/
-	private function getListDataClass() {
-		if(!$this->listDataClass) {
-			$this->listDataClass = singleton($this->owner->getSearchContext()->getResults(array())->dataClass());
-		}		
-		return $this->listDataClass;
-	}
-
-
-	/**
-	 * Determines whether the current model being managed is MultiSitesAware
-	 *
-	 * @return boolean
-	 **/
-	private function modelIsMultiSitesAware() {
-		$model = $this->getListDataClass();
-		return $model->hasExtension('MultisitesAware') || $model instanceof SiteTree;
-	}
+    /**
+     * Get and cache an instance of the data class currently being listed
+     *
+     * @return DataObject
+     **/
+    private function getListDataClass() {
+        /**
+         * Silverstripe-recipe 4.3.0 introduces changes that broke the
+         * previous approach to retrieving the model class.
+         *
+         * This is/will be fixed in silverstripe-recipe 4.3.1
+         *
+         * We've taken this approach so that Multisites can work with
+         * SS 4.3.0 so long as you don't use the MultisitesAware extension.
+         */
+        if ($this->listDataClass === null) {
+            // only true if silverstripe-recipe > 4.3.0
+            if ($this->owner->hasMethod('getModelClass')) {
+                $this->listDataClass = $this->owner->getModelClass();
+            }
+            // else false to bypass the MultisitesAware extension
+            else {
+                $this->listDataClass = false;
+            }
+        }
+        return $this->listDataClass;
+    }
+
+    /**
+     * Determines whether the current model being managed is MultiSitesAware
+     *
+     * @return boolean
+     **/
+    private function modelIsMultiSitesAware() {
+        $model = $this->getListDataClass();
+        // always false if using silverstripe-recipe <= 4.3.0
+        if ($model) {
+            $isAware = $model::has_extension(MultisitesAware::class);
+            $isSiteTree = in_array(SiteTree::class, ClassInfo::ancestry($model));
+            return $isAware || $isSiteTree;
+        }
+        return false;
+    }
 }