Hi there, I tried to extend the Member Object with a Friendship Relation.

Therefore the Member Object gets a many_many relation to itself.

Here is some code:

class BaseMember extends DataExtension {
    
    private static $many_many = array(
        'FriendsRequested' => 'Member'
    );
    
    private static $belongs_many_many = array(
        'FriendsAccepted' => 'Member.FriendsRequested'
    );
    
    public function Friends(){
        return $this->owner->FriendsRequested()->innerJoin("Member_FriendsRequested", "\"Member_FriendsRequested\".\"MemberID\" = \"FriendsAccepted\".\"ChildID\" AND \"Member_FriendsRequested\".\"ChildID\" = \"FriendsAccepted\".\"MemberID\"", "FriendsAccepted");
    }
}

Now I ran into the Problem, that a many_many relation to itself leads to a "Inverse component of Member.FriendsRequested not found (Member)" Error on ModelAdmin. Everywhere else this is working without any errors or Problems.

I allready tried to remove the FriendsRequested Tab from the CMS Fields (by using updateCMSFields), but without any success.

Does anyone of you have an idea, how to solve this, as I really need access to the ModelAdmin in the Backend again.

I tried to reverse engineer this error/bug and came across the problem, that in general the ModelAdmin results in an Inverse component Error when you have a multible many_many relations to the same object.

Here is some code which also fails:

class Category extends DataObject {
    
    private static $db = array(
        "Title" => "Varchar(255)"
    );
    
    private static $many_many = array(
        'BigProducts' => 'Product',
        'SmallProducts' => 'Product'
    );
}

class Product extends DataObject {
    
    private static $db = array(
        "Title" => "Varchar(255)"
    );
    
    private static $belongs_many_many = array(
        'BigCategories' => 'Category.BigProducts',
        'SmallCategories' => 'Category.SmallProducts'
    );
}

Hello Andre, I just had the same problem. The code with dot-notation worked for me perfectly fine in Silverstripe 3.1.6, but now I've updated to 3.1.9 it throws this error... it seems to me like something changed in the framework. But I can't figure out what or why and if it's a bug or a different approuch to things.

Did you manage to find a solution / the problem / a workaround?

I'm not sure if this helps, but here's a stackoverflow post addressing this issue with a custom getCMSFields() function...

Hi Looney, hi martimiz,

customizing the getCMSFields Method doesn't help. I allready tried that. But I also have halfway good news.

I solved the Problem, but you need to change the core (and currently I didn't checked my Patch for possible errors, that are followups).

In /framework/model/DataObject.php you have to change the many_many method:

	public function many_many($component = null) {

                ...

                                // Try belongs_many_many
				$belongsManyMany = Config::inst()->get($class, 'belongs_many_many', Config::UNINHERITED);
				$candidate = (isset($belongsManyMany[$component])) ? $belongsManyMany[$component] : null;
				if($candidate) {
					
// Here are my changes
					// If $candidate is of dot notation for multiple many_many relations to the same class
					if(strpos($candidate,'.') !== FALSE){
						$candidate=explode('.', $candidate);
						$candidate=$candidate[0];
					}
                                        
					$childField = $candidate . "ID";

// end of my changes

					// We need to find the inverse component name
				       
                                        ....
		}
		
		return isset($items) ? $items : null;
	}

I created a patch repository, that will overwrite some files within the silverstripe core using composer.

The following apptemplate can help you, how to use the fixes repository.

https://github.com/andrelohmann/silverstripe-apptemplate

It will be updated to Silverstripe 3.1.9 within the next two days (currently its on ss3.1.8).

Very Nice! Thanks a lot Andre! With your fix in DataObject it's working fine now! :)

you're welcome

but keep in mind, I didn't checked it for side effects, even if I'm using SS heavily to build real complex applications and I didn't found any side effect so far.