entc/gen: set foreign-key columns non-nullable for required edges

[a8m]

Note, this only applies to edges without circular references.
Fixed #1688 and #1374

[serbanmarti]

Is this still being worked on? This fix is really needed for my use case.

[ksthiele]

is this still active?

[edigaryev]

We faced this issue at @cirruslabs while trying to ensure consistency and I've tried reproducing the failed migration test locally and got this:

=== RUN   TestMySQL/56
    enttest.go:67: sql/schema: alter table "groups": Error 1830: Column 'group_info' cannot be NOT NULL: needed in a foreign key constraint 'test/groups_group_infos_info' SET NULL
    --- FAIL: TestMySQL/56 (0.05s)

The previous migration created by master had a ON DELETE SET NULL constraint on a group_info column, but the new migration tries to change the group_info column type to NOT NULL, which makes no sense without changing the constraint too and triggers error 1830.

It seems that the current migration logic is somewhat append-only and won't change any constraints:

ent/dialect/sql/schema/migrate.go

Lines 136 to 144 in 14cba0a

	// Create creates all schema resources in the database. It works in an "append-only"
	// mode, which means, it only create tables, append column to tables or modifying column type.
	//
	// Column can be modified by turning into a NULL from NOT NULL, or having a type conversion not
	// resulting data altering. From example, changing varchar(255) to varchar(120) is invalid, but
	// changing varchar(120) to varchar(255) is valid. For more info, see the convert function below.
	//
	// Note that SQLite dialect does not support (this moment) the "append-only" mode describe above,
	// since it's used only for testing.

@a8m do you think adding a separate migration option that will enable schema modifications such as constraint updates would be a reasonable way solve this?

I've also read in some issues that a work on a new migration engine is being done, do you have any plans to de-compose this task into smaller chunks and make this effort more transparent overall, so that the community could help?

[iwata]

@a8m Any progress on this pull request?

[a8m]

Hey all, this PR actually waited a long time for the new migration engine, due to migration failures, and thanks to github.com/ariga/atlas, this issue is resolved now and I plan to merge it on Sunday morning. CI is green, and the only thing left is to update the documentation.

If you didn't have a chance to see our v0.10 yesterday, here's the announcement post. Thanks 🙏 ❤️