laravel BelongsTo relationship with different databases not working

Question

I\'ve seen in several places to \"stay away\" from this, but alas - this is how my DB is built:

class Album extends Eloquent {

   // default connection

            


        

Answer 1

This is the way it worked for me:

In my .env and config/database.php i have defined my other connection => How to use multiple databases in Laravel

I updated my model this way:

class MyOtherDBModel extends Model
{
    protected $table = 'tablename';
    protected $connection = 'mysql2';

    public function __construct(array $attributes = [])
    {
        $this->table = env('DB_DATABASE_2').'.'.$this->table;
        parent::__construct();
    }
}

class MyModel extends Model
{
    public function myOtherModel()
    {
        return $this->belongsTo(MyOtherDBModel::class, 'field', 'field');
    }
}

Now i can call

$query = MyModel::whereHas('myOtherModel');

Answer 2

I had the same issue when relationship wasn't working off the model connection.

My solution was to override the belongsToMany method on the model trying to establish. See example below.

<?php

namespace App\Model;

use Illuminate\Database\Eloquent\Model;
use Illuminate\Database\Eloquent\Relations\BelongsToMany;

class ConnectionModel extends Model
{
    /**
     * Override method to allow inheriting connection of parent
     *
     * Define a many-to-many relationship.
     *
     * @param  string  $related
     * @param  string  $table
     * @param  string  $foreignKey
     * @param  string  $otherKey
     * @param  string  $relation
     * @return \Illuminate\Database\Eloquent\Relations\BelongsToMany|BelongsToMany
     */
    public function belongsToMany($related, $table = null, $foreignKey = null, $otherKey = null, $relation = null)
    {
        // If no relationship name was passed, we will pull backtraces to get the
        // name of the calling function. We will use that function name as the
        // title of this relation since that is a great convention to apply.
        if (is_null($relation)) {
            $relation = $this->getBelongsToManyCaller();
        }

        // First, we'll need to determine the foreign key and "other key" for the
        // relationship. Once we have determined the keys we'll make the query
        // instances as well as the relationship instances we need for this.
        $foreignKey = $foreignKey ?: $this->getForeignKey();

        $instance = new $related;

        // get connection from parent
        $instance->setConnection(parent::getConnectionName());

        $otherKey = $otherKey ?: $instance->getForeignKey();

        // If no table name was provided, we can guess it by concatenating the two
        // models using underscores in alphabetical order. The two model names
        // are transformed to snake case from their default CamelCase also.
        if (is_null($table)) {
            $table = $this->joiningTable($related);
        }

        // Now we're ready to create a new query builder for the related model and
        // the relationship instances for the relation. The relations will set
        // appropriate query constraint and entirely manages the hydrations.
        $query = $instance->newQuery();

        return new BelongsToMany($query, $this, $table, $foreignKey, $otherKey, $relation);
    }
}

Answer 3

It looks like Eager Loading will do what you want to do

Album::with(['genre' => function ($q) {
   $q->connection('Resources')
     ->where('genre', 'German HopScotch'); 
}]);

Answer 4

Solution for laravel v5.7 and above

class Album extends Eloquent {

   // default connection

   public function genre() {
       return $this->setConnection('Resources')->belongsTo('genre');
   }
...
}

Answer 5

Add the connection variable with the default connection on the genre model:

protected $connection = 'mysql';

I had some problems with the relationships by not adding this.

Answer 6

I found a really good article for this here: http://fideloper.com/laravel-multiple-database-connections

You basically have to specify your two connections in your config file like so:

<?php
return array(

    'default' => 'mysql',

    'connections' => array(

        # Our primary database connection
        'mysql' => array(
            'driver'    => 'mysql',
            'host'      => 'host1',
            'database'  => 'database1',
            'username'  => 'user1',
            'password'  => 'pass1'
            'charset'   => 'utf8',
            'collation' => 'utf8_unicode_ci',
            'prefix'    => '',
        ),

        # Our secondary database connection
        'mysql2' => array(
            'driver'    => 'mysql',
            'host'      => 'host2',
            'database'  => 'database2',
            'username'  => 'user2',
            'password'  => 'pass2'
            'charset'   => 'utf8',
            'collation' => 'utf8_unicode_ci',
            'prefix'    => '',
        ),
    ),
);

So your two connections are aliased to mysql and mysql2.

Then you can tell eloquent which 'alias' to use like so:

<?php

class SomeModel extends Eloquent {

    protected $connection = 'mysql2';

}

Then you can setup your relationships like normal.

tl;dr: Basically instead of specifying the table name as $connection in eloquent, specify the connection alias in your configuration and it should work.