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0 pointsdugmartin4y ago0 comments

It is tempting to just drop down to raw queries but then when I read about things like composable Ecto queries (https://medium.com/flatiron-labs/how-to-compose-queries-in-e...) it makes me want to stay at the higher abstraction level.

The final example in that post:

    EctoCars.Car 
    |> EctoCars.Car.with_color("blue") 
    |> EctoCars.Car.with_transmission("automatic") 
    |> EctoCars.Car.with_engine_horse_power(200) 
    |> EctoCars.Repo.all()

generates very clean SQL:

    SELECT c0."id", c0."color", c0."vin_number", c0."specification_id"
    FROM "cars" AS c0
    LEFT OUTER JOIN "specifications" AS s1 ON c0."specification_id" = s1."id"
    LEFT OUTER JOIN "transmissions" AS t2 ON s1."transmission_id" = t2."id"
    LEFT OUTER JOIN "engines" AS e3 ON s1."engine_id" = e3."id" 
    WHERE (c0."color" = $1) AND (t2."type" = $2) AND (e3."horse_power" > $3)

0 comments

pmontra4y ago

Yes, we use that pattern in the Elixir project I'm working on. But that's a simple query despite all the JOINs. It's just a waste of time to convert complex queries into Ecto. Maybe the reason is that I build them in the database using it as a REPL. Then I have working SQL and a lot of hard work to turn them into Elixir. Or Ruby, or Python or whatever. I played that game for far too long. I give up immediately now, write raw SQL and move on to the next productive task.

manusachi4y ago

I think the parent commenter is not saying to write your one time use query in elixir using wrapper modules with Ecto, but tried to show that queries generated by Ecto are pretty clean and understandable in compare to other popular DataMappers/ORMs

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