Some helpers to sparkle on top of Ecto to make queries easier, and to better join + preload associations, plus some changeset helpers and slow query logger


EctoSparkles #

Some helpers to sparkle on top of Ecto

  • EctoSparkles.proload/3 and EctoSparkles.join_preload/2 to join and preload associations with less verbosity
  • EctoSparkles.reusable_join/5 to avoid duplicating joins
  • EctoSparkles.Migrator to run migrations, rollbacks, etc in a release and EctoSparkles.AutoMigrator to automatically run them at startup.
  • EctoSparkles.DataMigration: a behaviour implemented for data migrations (generally backfills).
  • EctoSparkles.Log to log slow or possible N+1 queries with telemetry (showing stacktraces)
  • EctoSparkles.Changesets.Errors to generate readable errors for changesets

NOTE: you need to put something like config :ecto_sparkles, :otp_app, :your_otp_app_name in your app's config.

proload documentation #

A macro which tells Ecto to perform a join and preload of associations.

By default, Ecto preloads associations using a separate query for each association, which can degrade performance.

You can make it run faster by using a combination of join/preload, but that requires a bit of boilerplate (see examples below).

Examples using standard Ecto #

  |> join(:left, [o, activity: activity], assoc(:object), as: :object)
  |> preload([l, activity: activity, object: object], activity: {activity, [object: object]})

Ecto requires calling three different functions for this operation: Query.join/4, Query.assoc/3 and Query.preload/2.

Here's another example:

  |> join(:left, [i], assoc(i, :customer), as: :customer)
  |> join(:left, [i], assoc(i, :lines), as: :lines)
  |> preload([lines: v, customers: c], lines: v, customer: c)

Example using proload #

With proload, you can accomplish this with just one line of code:

proload(query, activity: [:object])

And for the other example:

proload(Invoice, [:customer, :lines])

As a bonus, it automatically makes use of reusable_join so calling it multiple times with the same association has no ill effects.

Example using join_preload #

join_preload is proload's sister macro with a slightly different syntax:

  join_preload(query, [:activity, :object])


  |> join_preload(:customer)
  |> join_preload(:lines)

reusable_join documentation #

A macro similar to Ecto.Query.join/{4,5}, but can be called multiple times
with the same alias.

Note that only the first join operation is performed, the subsequent ones that use the same alias
are just ignored. Also note that because of this behaviour, its mandatory to specify an alias when
using this function.

This is helpful when you need to perform a join while building queries one filter at a time,
because the same filter could be used multiple times or you could have multiple filters that
require the same join, which poses a problem with how the filter/3 callback work, as you
need to return a dynamic with the filtering, which means that the join must have an alias,
and by default Ecto raises an error when you add multiple joins with the same alias.

To solve this, it is recommended to use this macro instead of the default Ecto.Query.join/{4,5},
in which case there will be only one join in the query that can be reused by multiple filters.

Creating reusable joins #

|> reusable_join(:left, [t1], t2 in "other_table", on: ==, as: :other_a)
|> reusable_join(:left, [t1], t2 in "other_table", on: ==, as: :other_b)
  • Copyright (c) 2021 Bonfire developers

  • Copyright (c) 2020 Up Learn

  • Copyright (c) 2019 Joshua Nussbaum

  • join_preload was originally forked from Ecto.Preloader, licensed under WTFPL)

  • reusable_join was originally forked from QueryElf, licensed under Apache License Version 2.0

  • original code licensed under Apache License Version 2.0

Updated 23 Jan 2024

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