Many-to-many (belongsToMany) in Laravel - Step-by-Step Execution

Concept Flow - Many-to-many (belongsToMany)

Define Models

↓

Create Pivot Table

↓

Set belongsToMany in Model A

↓

Set belongsToMany in Model B

↓

Attach/Detach/Sync Relations

↓

Query Related Models

↓

Use Data in App

This flow shows how Laravel sets up and uses many-to-many relationships between two models using a pivot table.

Execution Sample

Laravel

class User extends Model {
  public function roles() {
    return $this->belongsToMany(Role::class);
  }
}

$user = User::find(1);
$roles = $user->roles;

This code defines a many-to-many relation from User to Role and fetches roles for user with ID 1.

Execution Table

Step	Action	Evaluation	Result
1	Call User::find(1)	User with ID 1 exists	User object loaded
2	Call $user->roles()	belongsToMany relation method runs	Query builder built to get roles linked to user 1
3	Execute SQL query on pivot table	Pivot table joins users and roles	Collection of Role objects returned
4	Assign roles to $roles variable	Roles fetched successfully	Roles collection ready for use
5	Use $roles in app	Iterate or display roles	Roles data shown or processed
6	End	No more actions	Execution stops

💡 All related roles for user 1 fetched; no further steps.

Variable Tracker

Variable	Start	After Step 1	After Step 2	After Step 3	After Step 4	Final
$user	null	User object with ID 1	User object	User object	User object	User object
$roles	null	null	Collection of Role objects	Collection of Role objects	Collection of Role objects	Collection of Role objects

Key Moments - 3 Insights

Why do we need a pivot table in many-to-many relationships?

The pivot table stores the links between two models. Without it, Laravel cannot know which records relate to each other. See execution_table step 3 where the pivot table is queried.

What does belongsToMany() return when called?

It returns a query builder for the related model. The actual data is fetched when you access or iterate the relation, as shown in execution_table step 3.

How does Laravel know which pivot table to use?

By default, Laravel uses the two model names in alphabetical order joined by an underscore. You can specify a custom table name in belongsToMany() if needed.

Visual Quiz - 3 Questions

Look at the execution table, what is stored in $roles after step 3?

A A SQL query string

B A collection of Role objects related to the user

C A User object

D Null

💡 Hint

Check the 'Result' column in step 3 of the execution_table.

At which step does Laravel query the pivot table to get related roles?

A Step 1

B Step 2

C Step 3

D Step 4

💡 Hint

Look at the 'Action' and 'Evaluation' columns in the execution_table for the pivot table query.

If the pivot table name was customized, where would you specify it?

A Inside the belongsToMany() method call

B In the User::find() method

C In the Role model's constructor

D In the database seeders

💡 Hint

belongsToMany() accepts the pivot table name as an optional second argument.

Concept Snapshot

Many-to-many relationships link two models via a pivot table.
Use belongsToMany() in both models to define the relation.
Laravel queries the pivot table to find related records.
Attach, detach, or sync methods manage links.
Access related models via the relation property or method.

Full Transcript

In Laravel, many-to-many relationships connect two models through a pivot table. You define this by adding a belongsToMany() method in both models. When you fetch a model and call this relation, Laravel builds a query joining the pivot table to get related records. The pivot table stores the links between the two models. You can manage these links with attach, detach, or sync methods. This example shows fetching roles related to a user by calling $user->roles(). The execution steps trace loading the user, building the query, querying the pivot table, and returning the related roles collection.