Relationships

When we built our application in Chapter 3, Your First Application, we made use of relationships. Each cat in our application was of a particular breed. However, instead of storing the name of the breed next to every individual cat and potentially having the breed repeating numerous times, we created a separate breeds table and each cat's breed was a value that referred to the ID of a record in that table. This gave us an example of two types of relationships: a cat belongs to a breed, but a breed can have many cats. This is defined as a one-to-many relationship.

There are other types of relationships, for each of which Eloquent provides good support:

• One-to-one

• Many-to-many

• Has-many-through

• Polymorphic relations

• Many-to-many polymorphic relations

Here, we will look through them with an example of each.

One-to-one

Sometimes, you may want to split data across multiple tables for ease of management, or because they represent two different parts of one entity. A common example is a user...