[tarzan]

fixes #4535

Sorry about the whitespace changes - mix formatter automatically runs in my editor, do I need to revert those changes?

Key Changes:

Core Implementation (lib/ecto/repo/preloader.ex)

Added a new clause to the add_preload_order/2 function that checks if the query already has order_by clauses:

defp add_preload_order([], query), do: query

defp add_preload_order(_order, %{order_bys: [_|_]} = query) do
  # Skip applying preload_order when query already has custom order_by clauses
  query
end

This ensures that when a custom query with its own ordering is provided, the :preload_order is not applied, allowing the custom order to take precedence.

Documentation Updates (lib/ecto/schema.ex)

Updated the documentation for :preload_order in both has_many/3 and many_to_many/3 to clarify the new behavior:

• Added a note explaining that custom query order_by clauses take precedence over :preload_order
• This applies to both association types

Test Coverage (integration_test/cases/preload.exs)

Added a comprehensive test case (custom query order_by overrides preload_order) that verifies:

• Without a custom query, :preload_order is applied (ascending order by text)
• With a custom query having order_by, the custom order takes precedence (descending order by text)

Changelog (CHANGELOG.md)

Added an entry documenting this enhancement for the next release.

[josevalim]

The integration tests are failing, can you please take a look?

     +integration-test *failed* |   1) test custom query order_by overrides preload_order (Ecto.Integration.PreloadTest)
     +integration-test *failed* |      /src/ecto/integration_test/cases/preload.exs:698
     +integration-test *failed* |      ** (ArgumentError) schema Ecto.Integration.Post does not have association or embed :force
     +integration-test *failed* |      code: post = TestRepo.preload(post, ordered_comments: query, force: true)
     +integration-test *failed* |      stacktrace:
     +integration-test *failed* |        (elixir 1.17.3) lib/enum.ex:2531: Enum."-reduce/3-lists^foldl/2-0-"/3
     +integration-test *failed* |        /src/ecto/integration_test/cases/preload.exs:711: (test)

[warmwaffles]

Are the formatting changes necessary to shim into this pr?

[josevalim]

@tarzan I have formatted those files on main, so you can rebase and it should keep the PR tiny!

[tarzan]

The integration tests are failing, can you please take a look?

     +integration-test *failed* |   1) test custom query order_by overrides preload_order (Ecto.Integration.PreloadTest)
     +integration-test *failed* |      /src/ecto/integration_test/cases/preload.exs:698
     +integration-test *failed* |      ** (ArgumentError) schema Ecto.Integration.Post does not have association or embed :force
     +integration-test *failed* |      code: post = TestRepo.preload(post, ordered_comments: query, force: true)
     +integration-test *failed* |      stacktrace:
     +integration-test *failed* |        (elixir 1.17.3) lib/enum.ex:2531: Enum."-reduce/3-lists^foldl/2-0-"/3
     +integration-test *failed* |        /src/ecto/integration_test/cases/preload.exs:711: (test)

This should be fixed now.

I rebased the code as well.

Can you re-run the workflow?

[josevalim]

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