impl Add support for Django reverse relationships #2071

[asukaminato0721]

Summary

Fixes #2071

Implemented Django reverse relationship synthesis by scanning model field bindings in the module, inferring reverse accessors for ForeignKey/ManyToManyField (and OneToOneField), parsing related_name (including %(class)s/%(app_label)s), and adding a RelatedManager helper for reverse FK accessors.

Notes/limits:

Reverse accessors are synthesized only from relation fields declared in the same module and with literal related_name/None (dynamic names are skipped).

Cross-module reverse inference isn’t covered yet. supported.

Test Plan

Added assertions for reverse accessors

[Copilot]

Pull request overview

This pull request implements support for Django reverse relationships, addressing issue #2071. The implementation synthesizes reverse accessors for ForeignKey, ManyToManyField, and OneToOneField by scanning model field bindings, inferring reverse accessors, parsing related_name (including template substitution for %(class)s and %(app_label)s), and adding a RelatedManager helper for reverse ForeignKey accessors.

Changes:

• Added reverse relationship field synthesis for Django models
• Implemented related_name template parsing with %(class)s and %(app_label)s support
• Added RelatedManager type support for ForeignKey reverse accessors

Reviewed changes

Copilot reviewed 3 out of 3 changed files in this pull request and generated no comments.

File	Description
pyrefly/lib/alt/class/django.rs	Core implementation of reverse relationship synthesis including relation kind detection, related_name parsing with template substitution, and manager type resolution
pyrefly/lib/test/django/foreign_key.rs	Added test assertion for ForeignKey reverse accessor (article_set) on Reporter model
pyrefly/lib/test/django/many_to_many.rs	Added test assertion for ManyToManyField reverse accessor (books) on Author model

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[migeed-z]

Thank you so much! I will import and take a closer look.

[meta-codesync]

@migeed-z has imported this pull request. If you are a Meta employee, you can view this in D90513475.

[rchen152]

Review automatically exported from Phabricator review in Meta.

[migeed-z]

Hello! we got to review the diff in more details. Here are some open questions:

• The implementation requires iterating over every single ClassField binding. Can we do better? this would be expensive for large django models. Can we store do one pass in the bindings phase and collect ForeignKey, ManyToManyField, and OneToOneField assignments and store the names of those fields in class metadata and go from there?
• Cross module support seems important to me on realistic codebases and ultimately the goal. Is this approach going in the right direction towards that?

[asukaminato0721]

Moved Django reverse-relationship synthesis to a module-level binding/index so we compute reverse fields once per module (instead of scanning every KeyClassField for each model).

The binder now records candidate relation fields during the class-body pass, and the solver builds a reverse-relation index keyed by target class that get_django_model_synthesized_fields can query.

[asukaminato0721]

Started cross‑module support by building a global reverse‑relation index once per solve and caching it in the thread state. The index merges each module’s KeyDjangoRelations result, so reverse accessors now come from all modules loaded in the current transaction (not just the current module).

This required exporting KeyDjangoRelations and adding LookupAnswer::modules() so the solver can enumerate available modules and combine their per‑module indexes.

[github-actions]

Diff from mypy_primer, showing the effect of this PR on open source code:

zulip (https://github.com/zulip/zulip)
- ERROR corporate/views/support.py:943:13-42: Object of class `RemoteZulipServer` has no attribute `remoterealm_set` [missing-attribute]
- ERROR zerver/actions/create_user.py:820:26-52: Object of class `UserProfile` has no attribute `direct_groups` [missing-attribute]
+ ERROR zerver/actions/create_user.py:833:28-55: Object of class `UserGroup` has no attribute `named_user_group` [missing-attribute]
- ERROR zerver/actions/uploads.py:136:44-66: Object of class `Message` has no attribute `attachment_set`
+ ERROR zerver/actions/uploads.py:136:44-66: Object of class `ScheduledMessage` has no attribute `attachment_set` [missing-attribute]
- Object of class `ScheduledMessage` has no attribute `attachment_set` [missing-attribute]
- ERROR zerver/actions/uploads.py:145:9-31: Object of class `Message` has no attribute `attachment_set`
+ ERROR zerver/actions/uploads.py:145:9-31: Object of class `ScheduledMessage` has no attribute `attachment_set` [missing-attribute]
- Object of class `ScheduledMessage` has no attribute `attachment_set` [missing-attribute]
- ERROR zerver/actions/uploads.py:157:35-57: Object of class `Message` has no attribute `attachment_set`
+ ERROR zerver/actions/uploads.py:157:35-57: Object of class `ScheduledMessage` has no attribute `attachment_set` [missing-attribute]
- Object of class `ScheduledMessage` has no attribute `attachment_set` [missing-attribute]
- ERROR zerver/actions/users.py:433:35-61: Object of class `UserProfile` has no attribute `direct_groups` [missing-attribute]
- ERROR zerver/lib/user_groups.py:778:17-43: Object of class `UserProfile` has no attribute `direct_groups` [missing-attribute]
- ERROR zerver/lib/user_groups.py:862:21-47: Object of class `UserProfile` has no attribute `direct_groups` [missing-attribute]
- ERROR zerver/lib/widget.py:142:12-34: Object of class `Message` has no attribute `submessage_set` [missing-attribute]
- ERROR zerver/management/commands/export_search.py:300:35-57: Object of class `Message` has no attribute `attachment_set` [missing-attribute]
- ERROR zerver/models/realms.py:1377:17-38: Object of class `Realm` has no attribute `realmdomain_set` [missing-attribute]
+ ERROR zerver/models/realms.py:1377:16-76: No matching overload found for function `list.__init__` called with arguments: (QuerySet[RealmDomain, dict[str, Any]]) [no-matching-overload]
- ERROR zerver/tests/test_custom_profile_data.py:460:26-66: Object of class `UserProfile` has no attribute `customprofilefieldvalue_set` [missing-attribute]
- ERROR zerver/tests/test_custom_profile_data.py:465:26-66: Object of class `UserProfile` has no attribute `customprofilefieldvalue_set` [missing-attribute]
- ERROR zerver/tests/test_message_fetch.py:5655:25-43: Object of class `Message` has no attribute `attachment_set` [missing-attribute]
- ERROR zerver/tests/test_message_fetch.py:5656:26-44: Object of class `Message` has no attribute `attachment_set` [missing-attribute]
- ERROR zerver/tests/test_message_fetch.py:5660:25-43: Object of class `Message` has no attribute `attachment_set` [missing-attribute]
- ERROR zerver/tests/test_message_fetch.py:5661:26-44: Object of class `Message` has no attribute `attachment_set` [missing-attribute]
- ERROR zerver/tests/test_message_fetch.py:5665:26-44: Object of class `Message` has no attribute `attachment_set` [missing-attribute]
- ::error file=corporate/views/support.py,line=943,col=13,endLine=943,endColumn=42,title=Pyrefly missing-attribute::Object of class `RemoteZulipServer` has no attribute `remoterealm_set`
- ::error file=zerver/actions/create_user.py,line=820,col=26,endLine=820,endColumn=52,title=Pyrefly missing-attribute::Object of class `UserProfile` has no attribute `direct_groups`
+ ::error file=zerver/actions/create_user.py,line=833,col=28,endLine=833,endColumn=55,title=Pyrefly missing-attribute::Object of class `UserGroup` has no attribute `named_user_group`
- ::error file=zerver/actions/uploads.py,line=136,col=44,endLine=136,endColumn=66,title=Pyrefly missing-attribute::Object of class `Message` has no attribute `attachment_set`%0AObject of class `ScheduledMessage` has no attribute `attachment_set`
+ ::error file=zerver/actions/uploads.py,line=136,col=44,endLine=136,endColumn=66,title=Pyrefly missing-attribute::Object of class `ScheduledMessage` has no attribute `attachment_set`
- ::error file=zerver/actions/uploads.py,line=145,col=9,endLine=145,endColumn=31,title=Pyrefly missing-attribute::Object of class `Message` has no attribute `attachment_set`%0AObject of class `ScheduledMessage` has no attribute `attachment_set`
+ ::error file=zerver/actions/uploads.py,line=145,col=9,endLine=145,endColumn=31,title=Pyrefly missing-attribute::Object of class `ScheduledMessage` has no attribute `attachment_set`
- ::error file=zerver/actions/uploads.py,line=157,col=35,endLine=157,endColumn=57,title=Pyrefly missing-attribute::Object of class `Message` has no attribute `attachment_set`%0AObject of class `ScheduledMessage` has no attribute `attachment_set`
+ ::error file=zerver/actions/uploads.py,line=157,col=35,endLine=157,endColumn=57,title=Pyrefly missing-attribute::Object of class `ScheduledMessage` has no attribute `attachment_set`
- ::error file=zerver/actions/users.py,line=433,col=35,endLine=433,endColumn=61,title=Pyrefly missing-attribute::Object of class `UserProfile` has no attribute `direct_groups`
- ::error file=zerver/lib/user_groups.py,line=778,col=17,endLine=778,endColumn=43,title=Pyrefly missing-attribute::Object of class `UserProfile` has no attribute `direct_groups`
- ::error file=zerver/lib/user_groups.py,line=862,col=21,endLine=862,endColumn=47,title=Pyrefly missing-attribute::Object of class `UserProfile` has no attribute `direct_groups`
- ::error file=zerver/lib/widget.py,line=142,col=12,endLine=142,endColumn=34,title=Pyrefly missing-attribute::Object of class `Message` has no attribute `submessage_set`
- ::error file=zerver/management/commands/export_search.py,line=300,col=35,endLine=300,endColumn=57,title=Pyrefly missing-attribute::Object of class `Message` has no attribute `attachment_set`
- ::error file=zerver/models/realms.py,line=1377,col=17,endLine=1377,endColumn=38,title=Pyrefly missing-attribute::Object of class `Realm` has no attribute `realmdomain_set`
+ ::error file=zerver/models/realms.py,line=1377,col=16,endLine=1377,endColumn=76,title=Pyrefly no-matching-overload::No matching overload found for function `list.__init__` called with arguments: (QuerySet[RealmDomain, dict[str, Any]])%0A  Possible overloads:%0A  () -> None%0A  (iterable: Iterable[RealmDomainDict], /) -> None [closest match]
- ::error file=zerver/tests/test_custom_profile_data.py,line=460,col=26,endLine=460,endColumn=66,title=Pyrefly missing-attribute::Object of class `UserProfile` has no attribute `customprofilefieldvalue_set`
- ::error file=zerver/tests/test_custom_profile_data.py,line=465,col=26,endLine=465,endColumn=66,title=Pyrefly missing-attribute::Object of class `UserProfile` has no attribute `customprofilefieldvalue_set`
- ::error file=zerver/tests/test_message_fetch.py,line=5655,col=25,endLine=5655,endColumn=43,title=Pyrefly missing-attribute::Object of class `Message` has no attribute `attachment_set`
- ::error file=zerver/tests/test_message_fetch.py,line=5656,col=26,endLine=5656,endColumn=44,title=Pyrefly missing-attribute::Object of class `Message` has no attribute `attachment_set`
- ::error file=zerver/tests/test_message_fetch.py,line=5660,col=25,endLine=5660,endColumn=43,title=Pyrefly missing-attribute::Object of class `Message` has no attribute `attachment_set`
- ::error file=zerver/tests/test_message_fetch.py,line=5661,col=26,endLine=5661,endColumn=44,title=Pyrefly missing-attribute::Object of class `Message` has no attribute `attachment_set`
- ::error file=zerver/tests/test_message_fetch.py,line=5665,col=26,endLine=5665,endColumn=44,title=Pyrefly missing-attribute::Object of class `Message` has no attribute `attachment_set`