Understanding Rails’ has_many through Relationship: Rails Basics

In Rails, establishing associations between models is a common practice. These associations define how different models are related to one another. One of the more complex associations is the has_many :through relationship, which is used when you want to set up a many-to-many relationship via an intermediate model. In this article, we will delve into the details of this association, provide examples, and share best practices.

Basics of the has_many :through Relationship

In a many-to-many relationship, many instances of one model can be associated with many instances of another model. However, Rails does not support many-to-many relations directly between two models. Instead, it uses a third, intermediary model to set up this relationship.

The has_many :through relationship is ideal for situations where you not only want to create a many-to-many relationship but also need to store additional data about the relationship.

Example: Users and Groups

Consider a scenario where you have two models: User and Group. A user can belong to many groups, and a group can have many users. Additionally, you want to store the date on which a user joined a group. Here's how you might set this up using a…