Filter Eloquent Queries with whereBelongsTo()

Use whereBelongsTo() to filter queries by related parent models without manually hardcoding foreign key column names.

Filtering child models by their parent relation usually involves specifying foreign keys explicitly (such as where('company_id', $company->id)).

The whereBelongsTo() method infers foreign keys and primary keys automatically from the model relationship definitions.

Basic Usage

use App\Models\Company;
use App\Models\User;

$company = Company::find(1);

// Standard manual foreign key check
$users = User::where('company_id', $company->id)->get();

// Clean, relationship-aware query
$users = User::whereBelongsTo($company)->get();

Specifying Named Relationships

If your model defines custom relationship names (for example, manager instead of user), pass the relationship name as the second argument:

use App\Models\Project;
use App\Models\User;

$manager = User::find(5);

// Explicit relationship name
$projects = Project::whereBelongsTo($manager, 'manager')->get();

Filtering by Collections of Models

whereBelongsTo() also accepts Eloquent collections to perform an automatic WHERE IN query:

$vipCompanies = Company::where('tier', 'vip')->get();

// Generates: WHERE company_id IN (1, 2, 3)
$users = User::whereBelongsTo($vipCompanies)->get();

Summary

• Automatically resolves foreign keys and primary keys from model relationships.
• Prevents bugs caused by hardcoded foreign key column names when relationships change.
• Supports both single model instances and model collections for WHERE IN operations.