Eloquent: Relationships

Eloquent: Relationships

• Introduction
• Defining Relationships
  • One To One
  • One To Many
  • One To Many (Inverse)
  • Many To Many
  • Has Many Through
  • Polymorphic Relations
  • Many To Many Polymorphic Relations
• Querying Relations
  • Relationship Methods Vs. Dynamic Properties
  • Querying Relationship Existence
  • Querying Relationship Absence
  • Counting Related Models
• Eager Loading
  • Constraining Eager Loads
  • Lazy Eager Loading
• Inserting & Updating Related Models
  • The save Method
  • The create Method
  • Belongs To Relationships
  • Many To Many Relationships
• Touching Parent Timestamps

Introduction

Database tables are often related to one another. For example, a blog post may have many comments, or an order could be related to the user who placed it. Eloquent makes managing and working with these relationships easy, and supports several different types of relationships:

• One To One
• One To Many
• Many To Many
• Has Many Through
• Polymorphic Relations
• Many To Many Polymorphic Relations

Defining Relationships

Eloquent relationships are defined as functions on your Eloquent model classes. Since, like Eloquent models themselves, relationships also serve as powerful query builders, defining relationships as functions provides powerful method chaining and querying capabilities. For example, we may chain additional constraints on this posts relationship:

$user->posts()->where('active', 1)->get();

But, before diving too deep into using relationships, let's learn how to define each type.