Introduction

This Laravel Eloquent extension adds support for JSON foreign keys to BelongsTo, HasOne, HasMany, HasOneThrough, HasManyThrough, MorphTo, MorphOne and MorphMany relationships.
It also provides many-to-many relationships with JSON arrays.

Compatibility

Database	Laravel
MySQL 5.7+	5.5.29+
MariaDB 10.2+	5.8+
PostgreSQL 9.3+	5.5.29+
SQLite 3.18+	5.6.35+
SQL Server 2016+	5.6.25+

Installation

composer require "staudenmeir/eloquent-json-relations:^1.1"

Use this command if you are in PowerShell on Windows (e.g. in VS Code):

composer require "staudenmeir/eloquent-json-relations:^^^^1.1"

Usage

• One-To-Many Relationships
  • Referential Integrity
• Many-To-Many Relationships
  • Array of IDs
  • Array of Objects
  • Query Performance

One-To-Many Relationships

In this example, User has a BelongsTo relationship with Locale. There is no dedicated column, but the foreign key (locale_id) is stored as a property in a JSON field (users.options):

class User extends Model
{
    use \Staudenmeir\EloquentJsonRelations\HasJsonRelationships;

    protected $casts = [
        'options' => 'json',
    ];

    public function locale()
    {
        return $this->belongsTo(Locale::class, 'options->locale_id');
    }
}

class Locale extends Model
{
    use \Staudenmeir\EloquentJsonRelations\HasJsonRelationships;

    public function users()
    {
        return $this->hasMany(User::class, 'options->locale_id');
    }
}

Remember to use the HasJsonRelationships trait in both the parent and the related model.

Referential Integrity

On MySQL, MariaDB and SQL Server you can still ensure referential integrity with foreign keys on generated/computed columns.

Laravel migrations support this feature on MySQL/MariaDB:

Schema::create('users', function (Blueprint $table) {
    $table->bigIncrements('id');
    $table->json('options');
    $locale_id = DB::connection()->getQueryGrammar()->wrap('options->locale_id');
    $table->unsignedBigInteger('locale_id')->storedAs($locale_id);
    $table->foreign('locale_id')->references('id')->on('locales');
});

Laravel migrations (5.7.25+) also support this feature on SQL Server:

Schema::create('users', function (Blueprint $table) {
    $table->bigIncrements('id');
    $table->json('options');
    $locale_id = DB::connection()->getQueryGrammar()->wrap('options->locale_id');
    $locale_id = 'CAST('.$locale_id.' AS INT)';
    $table->computed('locale_id', $locale_id)->persisted();
    $table->foreign('locale_id')->references('id')->on('locales');
});

There is a workaround for older versions of Laravel.

Many-To-Many Relationships

The package also introduces two new relationship types: BelongsToJson and HasManyJson

On Laravel 5.6.25+, you can use them to implement many-to-many relationships with JSON arrays.

In this example, User has a BelongsToMany relationship with Role. There is no pivot table, but the foreign keys are stored as an array in a JSON field (users.options):

Array of IDs

By default, the relationship stores pivot records as an array of IDs:

class User extends Model
{
    use \Staudenmeir\EloquentJsonRelations\HasJsonRelationships;

    protected $casts = [
       'options' => 'json',
    ];
    
    public function roles()
    {
        return $this->belongsToJson(Role::class, 'options->role_ids');
    }
}

class Role extends Model
{
    use \Staudenmeir\EloquentJsonRelations\HasJsonRelationships;

    public function users()
    {
       return $this->hasManyJson(User::class, 'options->role_ids');
    }
}

On the side of the BelongsToJson relationship, you can use attach(), detach(), sync() and toggle():

$user = new User;
$user->roles()->attach([1, 2])->save(); // Now: [1, 2]

$user->roles()->detach([2])->save();    // Now: [1]

$user->roles()->sync([1, 3])->save();   // Now: [1, 3]

$user->roles()->toggle([2, 3])->save(); // Now: [1, 2]

Array of Objects

You can also store pivot records as objects with additional attributes:

class User extends Model
{
    use \Staudenmeir\EloquentJsonRelations\HasJsonRelationships;

    protected $casts = [
       'options' => 'json',
    ];
    
    public function roles()
    {
        return $this->belongsToJson(Role::class, 'options->roles[]->role_id');
    }
}

class Role extends Model
{
    use \Staudenmeir\EloquentJsonRelations\HasJsonRelationships;

    public function users()
    {
       return $this->hasManyJson(User::class, 'options->roles[]->role_id');
    }
}

Here, options->roles is the path to the JSON array. role_id is the name of the foreign key property inside the record object:

$user = new User;
$user->roles()->attach([1 => ['active' => true], 2 => ['active' => false]])->save();
// Now: [{"role_id":1,"active":true},{"role_id":2,"active":false}]

$user->roles()->detach([2])->save();
// Now: [{"role_id":1,"active":true}]

$user->roles()->sync([1 => ['active' => false], 3 => ['active' => true]])->save();
// Now: [{"role_id":1,"active":false},{"role_id":3,"active":true}]

$user->roles()->toggle([2 => ['active' => true], 3])->save();
// Now: [{"role_id":1,"active":false},{"role_id":2,"active":true}]

Limitations: On SQLite and SQL Server, these relationships only work partially.

Query Performance

On PostgreSQL, you can improve the query performance with jsonb columns and GIN indexes.

Use this migration when the array of IDs/objects is the column itself (e.g. users.role_ids):

Schema::create('users', function (Blueprint $table) {
    $table->bigIncrements('id');
    $table->jsonb('role_ids');
    $table->index('role_ids')->algorithm('gin');
});

Use this migration when the array is nested inside an object (e.g. users.options->role_ids):

Schema::create('users', function (Blueprint $table) {
    $table->bigIncrements('id');
    $table->jsonb('options');
    $table->rawIndex('("options"->\'role_ids\')', 'users_options_index')->algorithm('gin'); // Laravel 7.10.3+
    //$table->index([DB::raw('("options"->\'role_ids\')')], 'users_options_index', 'gin');  // Laravel < 7.10.3
});

Contributing

Please see CONTRIBUTING and CODE OF CONDUCT for details.