Generate entity for duplicated many-to-many paths

[billy1624]

PR Info

• Closes 0.10.6: still issues with conflicting implementations of trait #1333

Bug Fixes

• The implementation of Related<R> with via and to methods will not be generated if there exists multiple paths via an intermediate table. Like in the schema defined below - Path 1. users <-> users_votes <-> bills, Path 2. users <-> users_saved_bills <-> bills

CREATE TABLE users
(
  id uuid  PRIMARY KEY  DEFAULT uuid_generate_v1mc(),
  email TEXT UNIQUE NOT NULL,
  ...
);

CREATE TABLE bills
(
  id uuid  PRIMARY KEY  DEFAULT uuid_generate_v1mc(),
  ...
);

CREATE TABLE users_votes
(
  user_id uuid REFERENCES users (id) ON UPDATE CASCADE ON DELETE CASCADE,
  bill_id uuid REFERENCES bills (id) ON UPDATE CASCADE ON DELETE CASCADE,
  vote boolean NOT NULL,
  CONSTRAINT users_bills_pkey PRIMARY KEY (user_id, bill_id)
);

CREATE TABLE users_saved_bills
(
  user_id uuid REFERENCES users (id) ON UPDATE CASCADE ON DELETE CASCADE,
  bill_id uuid REFERENCES bills (id) ON UPDATE CASCADE ON DELETE CASCADE,
  CONSTRAINT users_saved_bills_pkey PRIMARY KEY (user_id, bill_id)
);

Adapted from #1333 (comment)

[tyt2y3]

what are these bits about though

[billy1624]

Install nightly channel with rustfmt component. Then, run cargo +nightly fmt

[billy1624]

Only night's fmt respect rustfmt.toml config file that's why.

[billy1624]

This PR includes a written-entity to generated-entity test cases. Which works like this:

1. sea-orm is being added as dev-dependency on the codegen crate. All entity files under codegen/tests_cfg module are being compiled and checked.
2. The tests were performed at the end of transformer.rs. Using create_table_from_entity to generate SeaQuery create table statement from the SeaORM entity.
3. Then, the statement was passed to EntityTransformer and followed by EntityWriter::gen_compact_code_blocks.
4. Finally, assert the output from the writer againsts the file defined in codegen/tests_cfg

[tyt2y3]

This is a very substantial change and seems to only fix a special case. Can we postpone this?

[billy1624]

Okay, we can ship this with 0.11.1 and backport this to 0.10.x

Shall we?

[tyt2y3]

No. I mean, to postpone it after 0.11

[kev0960]

Just curious when this can be merged? It's the only blocker that we cannot upgrade to a newer version

[tyt2y3]

Even if this gets merged now there will still be some time before the next release.
I can rebase the branch onto master, so you can install it and try it out locally.

[github-actions]

🎉 Released In 0.12.1 🎉

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