April 2019
Beginner to intermediate
244 pages
6h 34m
English
Content preview from Programming EctoBecome an O’Reilly member and get unlimited access to this title plus top books and audiobooks from O’Reilly and nearly 200 top publishers, thousands of courses curated by job role, 150+ live events each month,
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Deleting Records with Associations
An important thing to consider with associations is what should happen to child records when a parent record is deleted. For example, if we delete an album, what should we do with the associated tracks? Ecto provides the on_delete: option to specify the desired behavior, but the exact implementation will vary depending on the database you’re using. Let’s take a closer look.
One approach is to define the behavior when creating the association. The has_many, has_one, and many_to_many functions all support the on_delete: option, which can have one of three values:
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:nothing—This is the default behavior: Ecto won’t try to do anything to the child records if the parent is deleted.
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:nilify_all—Ecto updates all ...
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O’Reilly covers everything we've got, with content to help us build a world-class technology community, upgrade the capabilities and competencies of our teams, and improve overall team performance as well as their engagement.Julian F.
I wanted to learn C and C++, but it didn't click for me until I picked up an O'Reilly book. When I went on the O’Reilly platform, I was astonished to find all the books there, plus live events and sandboxes so you could play around with the technology.Addison B.
I’ve been on the O’Reilly platform for more than eight years. I use a couple of learning platforms, but I'm on O'Reilly more than anybody else. When you're there, you start learning. I'm never disappointed.Amir M.
I'm always learning. So when I got on to O'Reilly, I was like a kid in a candy store. There are playlists. There are answers. There's on-demand training. It's worth its weight in gold, in terms of what it allows me to do.