Many-to-Many Relationships - Rest Generic Class

Rest Generic Class provides a powerful trait for managing many-to-many relationships with full CRUD support, pivot data, and complex filtering. This guide covers the ManagesManyToMany trait for controllers that expose belongsToMany relationships.

Overview

The trait provides:

List and show related entities with filtering, pagination, and ordering
Create and update related models through the relationship
Delete related models (with optional cascade)
Attach/detach existing entities (pivot-only operations)
Sync the entire relationship set
Toggle specific IDs
Update pivot fields without modifying the related model
Export related entities to Excel/PDF

Setup

Define the Relationship

Add the many-to-many relationship to your parent model:

use Illuminate\Database\Eloquent\Relations\BelongsToMany;

class User extends BaseModel
{
    const RELATIONS = ['addresses'];

    public function addresses(): BelongsToMany
    {
        return $this->belongsToMany(
            Address::class,
            'user_addresses',    // Pivot table
            'user_id',           // Foreign key for this model
            'address_id'         // Foreign key for related model
        )
        ->withPivot(['is_primary', 'label', 'expires_at'])
        ->withTimestamps();
    }
}

Use ->withPivot() to include custom pivot columns in responses. Without it, pivot data won’t be visible.

Add the Trait to Your Controller

use Ronu\RestGenericClass\Core\Traits\ManagesManyToMany;

class UserController extends RestController
{
    use ManagesManyToMany;

    protected array $manyToManyConfig = [
        'addresses' => [
            'relationship'  => 'addresses',        // BelongsToMany method name
            'relatedModel'  => Address::class,
            'pivotModel'    => UserAddress::class,
            'parentModel'   => User::class,
            'parentKey'     => 'user_id',
            'relatedKey'    => 'address_id',

            'mutation' => [
                'dataKey'       => ['Addresses', 'addresses'],
                'deleteRelated' => true,
                'pivotColumns'  => ['is_primary', 'label', 'expires_at'],
            ],
        ],
    ];
}

Use the inject middleware to set _relation and _scenario:

Route::prefix('users/{user_id}/addresses')->group(function () {
    // List and show
    Route::get('/', [UserController::class, 'listRelation'])
        ->middleware('inject:_relation,addresses');
    
    Route::get('/{relatedId}', [UserController::class, 'showRelation'])
        ->middleware('inject:_relation,addresses');
    
    // Attach operations
    Route::post('/', [UserController::class, 'attachRelation'])
        ->middleware('inject:_relation,addresses,_scenario,attach');
    
    Route::post('/sync', [UserController::class, 'attachRelation'])
        ->middleware('inject:_relation,addresses,_scenario,sync');
    
    // Detach
    Route::delete('/{relatedId}', [UserController::class, 'detachRelation'])
        ->middleware('inject:_relation,addresses,_scenario,detach');
    
    // Update pivot
    Route::put('/{relatedId}/pivot', [UserController::class, 'updatePivotRelation'])
        ->middleware('inject:_relation,addresses,_scenario,update_pivot');
});

Configuration Reference

Required Fields

Field	Description	Example
`relationship`	BelongsToMany method name on parent model	`'addresses'`
`relatedModel`	Fully qualified class name of related model	`Address::class`
`pivotModel`	Fully qualified class name of pivot model	`UserAddress::class`
`parentModel`	Fully qualified class name of parent model	`User::class`
`parentKey`	Foreign key column for parent in pivot table	`'user_id'`
`relatedKey`	Foreign key column for related model in pivot	`'address_id'`

Mutation Config (Optional)

Field	Type	Default	Description
`dataKey`	`string\|array`	`[]`	Keys to extract bulk data from request body
`deleteRelated`	`bool`	`true`	Delete related model when `deleteRelation` is called
`pivotColumns`	`array`	`[]`	Whitelist of allowed pivot columns (empty = allow all)

List all addresses for a user:

GET /api/v1/users/42/addresses

Response:

{
  "data": [
    {
      "id": 1,
      "street": "123 Main St",
      "city": "New York",
      "state": "NY",
      "zip": "10001",
      "pivot": {
        "user_id": 42,
        "address_id": 1,
        "is_primary": true,
        "label": "Home",
        "created_at": "2026-01-01T00:00:00.000000Z"
      }
    },
    {
      "id": 2,
      "street": "456 Broadway",
      "city": "New York",
      "state": "NY",
      "zip": "10002",
      "pivot": {
        "user_id": 42,
        "address_id": 2,
        "is_primary": false,
        "label": "Work",
        "created_at": "2026-02-15T00:00:00.000000Z"
      }
    }
  ]
}

With Filtering

GET /api/v1/users/42/addresses
Content-Type: application/json

{
  "oper": {
    "and": ["state|=|NY", "is_primary|=|true"]
  }
}

With Pagination

GET /api/v1/users/42/addresses
Content-Type: application/json

{
  "pagination": {
    "page": 1,
    "pageSize": 10
  }
}

With Ordering

GET /api/v1/users/42/addresses
Content-Type: application/json

{
  "orderby": [{"label": "asc"}]
}

GET /api/v1/users/42/addresses/1

Response:

{
  "id": 1,
  "street": "123 Main St",
  "city": "New York",
  "state": "NY",
  "zip": "10001",
  "pivot": {
    "user_id": 42,
    "address_id": 1,
    "is_primary": true,
    "label": "Home"
  }
}

Attach Operations

Attach operations link existing entities without creating new ones.

Single Attach

Attach address ID 5 with pivot data:

POST /api/v1/users/42/addresses
Content-Type: application/json

{
  "address_id": 5,
  "is_primary": true,
  "label": "Home"
}

Response:

{
  "attached": [5]
}

Bulk Attach

Attach multiple addresses at once:

POST /api/v1/users/42/addresses/bulk
Content-Type: application/json

{
  "addresses": [
    {"address_id": 5, "is_primary": true, "label": "Home"},
    {"address_id": 8, "is_primary": false, "label": "Work"}
  ]
}

Response:

{
  "attached": [5, 8]
}

Sync Operation

Sync replaces the entire relationship set. IDs not in the sync payload are detached.

Sync with ID Array

POST /api/v1/users/42/addresses/sync
Content-Type: application/json

[1, 2, 3]

Result:

User 42 now has exactly 3 addresses (1, 2, 3)
Any other addresses are detached
No pivot data is updated

Sync with Objects

POST /api/v1/users/42/addresses/sync
Content-Type: application/json

[
  {"address_id": 1, "is_primary": true, "label": "Home"},
  {"address_id": 2, "is_primary": false, "label": "Work"},
  {"address_id": 3, "label": "Vacation"}
]

Sync with Laravel Map Format

POST /api/v1/users/42/addresses/sync
Content-Type: application/json

{
  "1": {"is_primary": true, "label": "Home"},
  "2": {"is_primary": false, "label": "Work"},
  "3": {"label": "Vacation"}
}

Response (all formats):

{
  "attached": [2, 3],
  "detached": [7, 9],
  "updated": [1]
}

Toggle Operation

Toggle reverses the attachment status: attached IDs become detached, detached IDs become attached.

POST /api/v1/users/42/addresses/toggle
Content-Type: application/json

[1, 2, 3]

Before:

User has addresses: [1, 5, 7]

After toggle:

User has addresses: [2, 3, 5, 7]
1 was detached (was attached)
2 and 3 were attached (were detached)
5 and 7 unchanged (not in toggle list)

Response:

{
  "attached": [2, 3],
  "detached": [1]
}

Detach Operations

Single Detach

Remove the pivot row (keeps the Address model):

DELETE /api/v1/users/42/addresses/5

Response:

{
  "detached": 1
}

Bulk Detach

DELETE /api/v1/users/42/addresses/bulk
Content-Type: application/json

[5, 8, 12]

Response:

{
  "detached": 3
}

Update Pivot Fields

Update pivot data without changing the related model.

Single Pivot Update

PUT /api/v1/users/42/addresses/5/pivot
Content-Type: application/json

{
  "is_primary": true,
  "label": "Main Office"
}

Response:

{
  "id": 5,
  "street": "123 Main St",
  "pivot": {
    "user_id": 42,
    "address_id": 5,
    "is_primary": true,
    "label": "Main Office"
  }
}

Bulk Pivot Update

PUT /api/v1/users/42/addresses/pivot/bulk
Content-Type: application/json

{
  "addresses": [
    {"address_id": 5, "is_primary": true, "label": "Main Office"},
    {"address_id": 8, "is_primary": false, "label": "Warehouse"}
  ]
}

Pivot Column Whitelist

The pivotColumns config provides a security whitelist:

'mutation' => [
    'pivotColumns' => ['is_primary', 'label', 'expires_at'],
],

How It Works

With the whitelist above: Request:

{
  "address_id": 5,
  "is_primary": true,
  "label": "Home",
  "approved_at": "2025-01-01",
  "internal_notes": "VIP customer"
}

Actual pivot data stored:

{
  "is_primary": true,
  "label": "Home"
}

approved_at and internal_notes are silently stripped (not in whitelist).

When pivotColumns is empty or not set, all pivot columns are accepted (backward compatible).

Create new related entities through the relationship.

Create Single

POST /api/v1/users/42/addresses/create
Content-Type: application/json

{
  "street": "789 Park Ave",
  "city": "New York",
  "state": "NY",
  "zip": "10003"
}

Response (201 Created):

{
  "success": true,
  "model": {
    "id": 15,
    "street": "789 Park Ave",
    "city": "New York",
    "state": "NY",
    "zip": "10003"
  }
}

Create Bulk

POST /api/v1/users/42/addresses/create/bulk
Content-Type: application/json

{
  "addresses": [
    {"street": "111 First St", "city": "Boston", "state": "MA", "zip": "02101"},
    {"street": "222 Second St", "city": "Boston", "state": "MA", "zip": "02102"}
  ]
}

PUT /api/v1/users/42/addresses/5
Content-Type: application/json

{
  "street": "123 Main Street",
  "zip": "10001-5555"
}

By default, deleting a relation also deletes the related model.

Single Delete

DELETE /api/v1/users/42/addresses/5/delete

This:

Detaches the address from user 42
Deletes the Address model (if deleteRelated=true)

Response:

{
  "success": true,
  "model": {
    "id": 5,
    "street": "123 Main St",
    ...
  }
}

Pivot-Only Removal

To keep the Address model and only remove the pivot row, configure:

'mutation' => [
    'deleteRelated' => false,
],

Now DELETE only removes the pivot row.

Export to Excel

GET /api/v1/users/42/addresses/export/excel?filename=user-addresses.xlsx

Optional parameters:

columns: Specify columns to export
select, oper, orderby: Apply filters before export

Export to PDF

GET /api/v1/users/42/addresses/export/pdf?filename=addresses.pdf&template=pdf

Real-World Examples

User Addresses (CRM)

UserController.php

protected array $manyToManyConfig = [
    'addresses' => [
        'relationship'  => 'addresses',
        'relatedModel'  => Address::class,
        'pivotModel'    => UserAddress::class,
        'parentModel'   => User::class,
        'parentKey'     => 'user_id',
        'relatedKey'    => 'address_id',
        'mutation' => [
            'dataKey'       => ['Addresses', 'addresses'],
            'deleteRelated' => false, // Keep addresses when detaching
            'pivotColumns'  => ['is_primary', 'label', 'address_type'],
        ],
    ],
];

Product Tags (E-commerce)

ProductController.php

protected array $manyToManyConfig = [
    'tags' => [
        'relationship'  => 'tags',
        'relatedModel'  => Tag::class,
        'pivotModel'    => ProductTag::class,
        'parentModel'   => Product::class,
        'parentKey'     => 'product_id',
        'relatedKey'    => 'tag_id',
        'mutation' => [
            'dataKey'       => ['Tags', 'tags'],
            'deleteRelated' => false, // Keep tags when detaching
            'pivotColumns'  => ['sort_order'],
        ],
    ],
];

Course Enrollments (LMS)

CourseController.php

protected array $manyToManyConfig = [
    'students' => [
        'relationship'  => 'students',
        'relatedModel'  => User::class,
        'pivotModel'    => Enrollment::class,
        'parentModel'   => Course::class,
        'parentKey'     => 'course_id',
        'relatedKey'    => 'user_id',
        'mutation' => [
            'dataKey'       => ['Students', 'students'],
            'deleteRelated' => false,
            'pivotColumns'  => ['enrolled_at', 'completed_at', 'grade', 'status'],
        ],
    ],
];

Next Steps

Relation Loading

Learn eager loading for many-to-many relationships

Bulk Operations

Optimize bulk attach/detach operations

Permissions

Secure many-to-many endpoints with Spatie

API Reference

Complete many-to-many API reference

Evidence

File: src/Core/Traits/ManagesManyToMany.php
Lines: 16-1191 (entire file)
Implements all many-to-many operations including listRelation, attachRelation, detachRelation, updatePivotRelation
File: documentacion/doc-en/03-usage/05-many-to-many.md
Lines: 1-391
Complete documentation of the trait with examples and configuration

Get Started

Installation

Core Concepts

Guides

Configuration

​Overview

​Setup

​Configuration Reference

​Required Fields

​Mutation Config (Optional)

​Listing Related Entities

​With Filtering

​With Pagination

​With Ordering

​Showing a Single Related Entity

​Attach Operations

​Single Attach

​Bulk Attach

​Sync Operation

​Sync with ID Array

​Sync with Objects

​Sync with Laravel Map Format

​Toggle Operation

​Detach Operations

​Single Detach

​Bulk Detach

​Update Pivot Fields

​Single Pivot Update

​Bulk Pivot Update

​Pivot Column Whitelist

​How It Works

​Create and Update Related Models

​Create Single

​Create Bulk

​Update Related Model

​Delete Related Models

​Single Delete

​Pivot-Only Removal

​Export Related Entities

​Export to Excel

​Export to PDF

​Real-World Examples

​User Addresses (CRM)

​Product Tags (E-commerce)

​Course Enrollments (LMS)

​Next Steps

Relation Loading

Bulk Operations

Permissions

API Reference

​Evidence

Build docs developers (and LLMs) love

Overview

Setup

Configuration Reference

Required Fields

Mutation Config (Optional)

Listing Related Entities

With Filtering

With Pagination

With Ordering

Showing a Single Related Entity

Attach Operations

Single Attach

Bulk Attach

Sync Operation

Sync with ID Array

Sync with Objects

Sync with Laravel Map Format

Toggle Operation

Detach Operations

Single Detach

Bulk Detach

Update Pivot Fields

Single Pivot Update

Bulk Pivot Update

Pivot Column Whitelist

How It Works

Create and Update Related Models

Create Single

Create Bulk

Update Related Model

Delete Related Models

Single Delete

Pivot-Only Removal

Export Related Entities

Export to Excel

Export to PDF

Real-World Examples

User Addresses (CRM)

Product Tags (E-commerce)

Course Enrollments (LMS)

Next Steps

Evidence