This is optimization tags for ManyToMany relationship with Post model for attaching not existing tags.

tags.php

public function storePost(Request $request)
	{
    	$notexistsTags = array();
    	$existsTags = Tag::whereIn('id', $request->input('tag_name'))->get();

    	foreach($request->input('tag_name') as $tag_name) {
            // Check if tag currently exist in database
    		foreach($existsTags as $tag) {
    			$match = false;
    			if($tag_name == $tag->id) {
    				$match = true;
    				break;
    			}
    		}
            // If tag from user's input was not matched to tag in database
            // add it to the $notexistsTags array.
    		if(!$match) {
    			$notexistsTags['tag_name'] = $tag_name;
    		}
    	}

    	//Get a pluck ID exists tags
    	$exTags = $existsTags->pluck('id')->toArray();

    	//Create not exists tags
    	$createdTags = Tag::create($notexistsTags);

    	//Get ID tags which was created
    	$getTagsId = Tag::whereIn('id', $createdTags)->pluck('id')->toArray();

    	//Add exists and not exists tags to one array for save it with attach posts
    	$tagsToAdd = array_merge($exTags, $getTagsId);
    }