Laravel : Call to undefined method Illuminate\Database\Eloquent\Collection::save()

Question

I am basically trying to get a specific row from my table and update it, however, I end up getting a collection for which save method is not defined as the error says in my Title. Can you please tell me what is wrong in the below code. I have also tried it without the get method. But in that case I get a different error. Also, please let me know if there is any better approach to retrieve a row from a table with two primary keys(userId, folderName) in this case. Thank you :)

$tempFolder =   Message_Folders::where('userId',"=",1)->where('folderName',"=",$imap_folder['name'])->get();
if($tempFolder==null){//If not existing, however in this example assume that it exists
        $tempFolder =  new Message_Folders();
        $tempFolder->userId = 1;    
        $tempFolder->folderName = $imap_folder['name'];
        }
        $tempFolder->flags = $imap_folder['status']->flags;
        $tempFolder->messages = $imap_folder['status']->messages;
        $tempFolder->recent = $imap_folder['status']->recent;
        $tempFolder->unseen = $imap_folder['status']->unseen;
        $tempFolder->uidnext = $imap_folder['status']->uidnext;
        $tempFolder->uidvalidity = $imap_folder['status']->uidvalidity;
        $tempFolder->save();

Edit 1:

After Updating the code as mentioned in the first answer, now I get a new error.

SQLSTATE[42S22]: Column not found: 1054 Unknown column 'id' in 'where clause' (SQL: update message_folders set recent = 4, updated_at = 2014-03-08 13:34:10 where id is null)

Please refer to the code below:( Also, if all the values are same then it works fine(since the update is actually not happening))

$tempFolder =   $this->folders->where('userId',"=",1)->where('folderName',"=",$imap_folder['name'])->first();
        if($tempFolder==null){
        $tempFolder =  new Message_Folders();
        $tempFolder->userId = 1;    
        $tempFolder->folderName = $imap_folder['name'];
        }
        $tempFolder->flags = $imap_folder['status']->flags;
        $tempFolder->messages = $imap_folder['status']->messages;
        $tempFolder->recent = 4;
        $tempFolder->unseen = $imap_folder['status']->unseen;
        $tempFolder->uidnext = $imap_folder['status']->uidnext;
        $tempFolder->uidvalidity = $imap_folder['status']->uidvalidity;

        $tempFolder->save();

Edit 2: Part of migration file for the table mentioned in the above code:

public function up()
    {
        Schema::create('message_folders', function(Blueprint $table) {
           $table->integer('userId');
           $table->string('folderName', 200);
           $table->integer('flags');
           $table->integer('messages');
           $table->integer('recent');
           $table->integer('unseen');
           $table->integer('uidnext');
           $table->integer('uidvalidity');
           $table->timestamps();
           $table->primary(array('userId','folderName'));
        });
    }

Answer 1

The following line, uses the get method of Query Builder:

$tempFolder =   Message_Folders::where('userId',"=",1)->where('folderName',"=",$imap_folder['name'])->get();

It will retrieve all rows from that model (filtered by where condition of course). So you are getting a Collection instead of an instance of the model.

To retrieve a single row from your query you can use first method:

//returns a single row from the query
$tempFolder =   Message_Folders::where('userId',"=",1)->where('folderName',"=",$imap_folder['name'])->first();