Implementing a Laravel 4 Pivot Table using Eloquent - mysql

Question

I've got the following structure in my database:
-shared_resources table
-tags table
-shared_resource_tag table
There is a many to many relationship between shared_resources and tags. When I am creating a shared_resource I do the following:
Add the shared_resource to the shared_resources table
Add the tags to the tags table
Add the shared_resource_id and the tag_id to the shared_resource_tag table
I can manage to get through steps 1 and 2 but for some reason I am unable to make any entries to the pivot table. I don't know why. I set up the relationships in my models accordingly:
SharedResource:
class SharedResource extends Eloquent{
public function tags(){
return $this->belongsToMany('Tag');
}
}
Tag:
class Tag extends Eloquent{
public function sharedResources(){
return $this->belongsToMany('SharedResource');
}
}
Then when I am creating the entries I do this:
$tags = Array();
$tags = explode(',', Input::get('tags'));
foreach($tags as $tag){
$newTag = new Tag;
$newTag->name = $tag;
$newTag->save();
}
//Pivot table entry
$resource->tags()->sync($tags);
$resource->save();
The code above runs into an error:
SQLSTATE[42S22]: Column not found: 1054 Unknown column 'shared_resource_id' in 'where clause' (SQL: select `tag_id` from `shared_resource_tag` where `shared_resource_id` is null)
I'm very confused as to whats going on, I understood that Eloquent made implementing these n:n relationships easy.

Answer 1

The sync() method will need the id's of the tags, and not the string names which you are giving it. You can try something like:
$tags = Array();
$tagIds = Array();
$tags = explode(',', Input::get('tags'));
foreach($tags as $tag){
$newTag = new Tag;
$newTag->name = $tag;
$newTag->save();
$tagIds[] = $newTag->id;
}
//Pivot table entry
$resource->tags()->sync($tagIds);
$resource->save();
You can find more info here under Using Sync To Attach Many To Many Models

Answer 2

$tags = explode(',', Input::get('tags'));
// Create or add tags
$tagIds = array();
if ( $tags )
{
$found = $this->tag->findOrCreate( $tags );
foreach ( $found as $tag )
{
$tagIds[ ] = $tag->id;
}
}
// Assign set tags to model
$model->tags()->sync( $tagIds );