Active Record Pattern

Also Known As

TL;DR

Explanation

Active Record (Martin Fowler, PoEAA) places persistence logic inside the domain object: User::find(1), $user->save(), $user->delete(). The object maps directly to a database row. Advantages: simple, low boilerplate, excellent for CRUD applications. Disadvantages: couples domain logic to persistence, makes unit testing without a database hard, violates SRP, and becomes unwieldy for complex domain logic. Laravel's Eloquent, Ruby on Rails, Django ORM are all Active Record implementations.

Common Misconception

Why It Matters

Common Mistakes

• Business logic inside Active Record models — they become unmaintainable God Objects.
• Unit testing Active Record models without a database — requires database setup, making tests slow.
• N+1 queries from lazy loading — always eager-load relationships with with() in Eloquent.
• Using Active Record when a complex aggregate requires multiple tables — use Repository instead.

Avoid When

• Domain logic is complex — mixing business rules with persistence makes both harder to test and change.
• You need to support multiple storage backends or swap databases; the object is tightly coupled to one schema.
• Writing unit tests that should not touch a database — the persistence coupling forces slow integration tests.

When To Use

• Simple CRUD-heavy apps where domain logic is thin and co-locating persistence with data is acceptable.
• Rapid prototyping or internal tools where the overhead of a separate data mapper is not justified.
• Teams already using a framework (Laravel Eloquent, Rails) where Active Record is the idiomatic default.

Code Examples

// Active Record model doing too much:
class Order extends Model {
    public function process(): void {
        // Validation, pricing, inventory, emails all in one class
        if ($this->total > $this->customer->credit_limit) throw new Exception();
        $this->status = 'processing';
        $this->save();
        $this->inventory->decrement($this->items);
        Mail::send(new OrderConfirmation($this));
        // Untestable without DB, email service, inventory service
    }
}

// Active Record for simple CRUD — appropriate:
class User extends Model {
    protected $fillable = ['name', 'email'];
    protected $hidden   = ['password'];

    public function orders(): HasMany {
        return $this->hasMany(Order::class);
    }
}
// Simple — maps rows to objects, relationships via ORM
// Complex domain logic extracted to dedicated service classes

References

• ↗ https://www.martinfowler.com/eaaCatalog/activeRecord.html

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