In this episode, we're digging into the hasManyThrough relationship in Laravel. At first, this relationship type might sound a bit confusing, but it’s actually super handy for accessing models that are related to each other through a third model—models that aren't directly connected to your original model.
To get a grasp of this, we walk through a practical example: Imagine a user who can create many projects, and each project can have many files. Now, there isn’t a direct relationship between the user and the files, but with a hasManyThrough, you can easily get all the files a user has uploaded, even though they’re technically attached to projects.
We start from scratch: creating the migrations for users, projects, and files, seeding some sample data, and setting up the basic hasMany
relationships (user → projects, project → files). Then, the real fun starts—we set up a hasManyThrough
on the user to directly fetch all their files across all projects.
Next, we put this into action by building a couple of simple endpoints: one to list a user’s projects and their files, and another to show all files a user has, regardless of project. We also touch on the syntax variations for hasManyThrough
—Laravel gives you a few choices, so you can pick whichever one feels clearest for your codebase.
We also look at how to display the project a file belongs to, and finish up by checking out query efficiency with the Laravel Debug Bar. To avoid crazy numbers of queries, we demonstrate how to eager load related models, making sure our app scales nicely.
By the end, you'll have a much better sense of when and how to use hasManyThrough
—it's a really useful tool for when you need to get to those "distant" related models in Laravel!