this post was submitted on 24 Oct 2023
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Programming
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I much prefer the repository pattern, as used by sequel and Ecto
Your models are essentially just enhanced structs. They hold information about the shape of data. Generally don't hold any validations or logic related to storing the data. You perform changes on the data using changesets, which handle validation and generating the transaction to persist the data
It works extremely well, and I've yet to encounter the funky problems ActiveRecord could give you
OK, but what about reading the data?
I've never had a problem writing to a database with an ORM. The problems happen when you try to read data (quickly and efficiently).
I agree, it’s even what I mostly use the ORM for, writing is so easy that way and results in far more succinct code.
Data comes out as a map or keyword list, which is then turned into the repository struct in question. If you want raw db data you can get that too. And you can have multiple structs that are backed by the same persistent dataset. It's quite elegant.
Queries themselves are constructed using a language that is near SQL, but far more composable:
Queries themselves are composable
And can be written in a keyword style, like the above examples, or a functional style, like the rest of elixir:
None of these "queries" will execute until you tell the Repo to do something. For that, you have commands like
Repo.all
andRepo.one
, the latter of which sticks alimit: 1
on the end of the provided queryI wouldn't call that "near" SQL, I'd basically just call it SQL. Nothing wrong with that... SQL is great, and using proper language constructs instead of strings makes it even better... but it's not solving the some problem as an ORM.