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many-to-many nullable columns with through#852

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collerek merged 2 commits intoormar-orm:masterfrom
nikelborm:many-to-many-nullable-columns
Apr 22, 2026
Merged

many-to-many nullable columns with through#852
collerek merged 2 commits intoormar-orm:masterfrom
nikelborm:many-to-many-nullable-columns

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@nikelborm
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@nikelborm nikelborm commented Sep 27, 2022

such code:

...
class TickerCollection(ormar.Model):
  class Meta(BaseMeta):
    tablename = "ticker_collection"

  id: int = ormar.Integer(name="ticker_collection_id", nullable=False, primary_key=True, autoincrement=True)

  createdByUser: Optional[User] = ormar.ForeignKey(User, name="created_by_user_id", nullable=True, unique=False)
  isPublic: bool                = ormar.Boolean(         name="is_public",          nullable=False, default=False)
  name: str                     = ormar.Text(            name="name",               nullable=False)
  description: str              = ormar.Text(            name="description",        nullable=True)
  tickers: Optional[List[Ticker]] = ormar.ManyToMany(
    to=Ticker,
    through=TickerToTickerCollection,
    related_name="tickerCollections",
    through_relation_name="ticker_collection_id",
    through_reverse_relation_name="ticker_id",
    # is_through_relation_column_nullable=False,
    # is_through_reverse_relation_column_nullable=False,
  )
...

cause such migration:

...
op.create_table('ticker_to_ticker_collection',
    sa.Column('id', sa.Integer(), nullable=False),
    sa.Column('ticker_id', sa.Integer(), nullable=True),
    sa.Column('ticker_collection_id', sa.Integer(), nullable=True),
    sa.ForeignKeyConstraint(['ticker_collection_id'], ['ticker_collection.ticker_collection_id'], name='asd1', onupdate='CASCADE', ondelete='CASCADE'),
    sa.ForeignKeyConstraint(['ticker_id'], ['ticker.ticker_id'], name='asd2', onupdate='CASCADE', ondelete='CASCADE'),
    sa.PrimaryKeyConstraint('id')
    )
...

Here ticker_id and ticker_collection_id are nullable by default, and there is no built-in way to set them non nullable.
I tried to set sql_nullable and nullable in arguments of ormar.ManyToMany but looks like it affects only typing information.
So then I added these two parameters, that will allow to override nullability of both through columns.

@collerek collerek force-pushed the many-to-many-nullable-columns branch from 77fae53 to 4b7de5a Compare December 10, 2022 16:22
collerek
collerek requested changes Dec 10, 2022
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Comment thread ormar/fields/many_to_many.py Outdated
Comment on lines +127 to +128
is_through_relation_column_nullable = kwargs.pop("is_through_relation_column_nullable", None)
is_through_reverse_relation_column_nullable = kwargs.pop("is_through_reverse_relation_column_nullable", None)
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@collerek collerek Dec 10, 2022

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Can you rename it to shorter names: through_relation_nullable and through_reverse_relation_nullable

Comment thread ormar/models/helpers/sqlalchemy.py Outdated
)
create_and_append_m2m_fk(
model=model_field.owner, model_field=model_field, field_name=child_name
model=model_field.owner, model_field=model_field, field_name=child_name, nullable=model_field.is_through_relation_column_nullable,
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@collerek collerek Dec 10, 2022

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Can you add missing tests for setting that column settings nullable/ not nullable and different expected behavior?

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collerek commented Dec 10, 2022

Sorry for the long review time!

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codecov Bot commented May 26, 2024 •
edited
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Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 100.00%. Comparing base (7f3149d) to head (ccbd159).

Additional details and impacted files

Impacted file tree graph

@@            Coverage Diff            @@
##            master      #852   +/-   ##
=========================================
  Coverage   100.00%   100.00%           
=========================================
  Files          204       204           
  Lines        14845     14847    +2     
=========================================
+ Hits         14845     14847    +2
Files Coverage Δ
ormar/fields/many_to_many.py 100.00% <100.00%> (ø)
ormar/models/helpers/sqlalchemy.py 100.00% <ø> (ø)

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codspeed-hq Bot commented May 26, 2024

CodSpeed Performance Report

Merging #852 will degrade performances by 12.33%

Comparing nikelborm:many-to-many-nullable-columns (ccbd159) with master (7f3149d)

Summary

❌ 1 regressions
✅ 83 untouched benchmarks

⚠️ Please fix the performance issues or acknowledge them on CodSpeed.

Benchmarks breakdown

Benchmark master nikelborm:many-to-many-nullable-columns Change
❌ test_deleting_individually[10] 8.6 ms 9.8 ms -12.33%

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nikelborm commented May 26, 2024 •
edited
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Hi @collerek
Since I wrote this PR, long time passed. At the time I wasn't much experienced in python\ormar and didn't have much time, so I wasn't able to properly write tests on this PR and fix your reviews, but now I hope I'm soon will be able to finish it

@collerek @claude
feat(relations): allow configuring nullability of M2M through FK colu…
0f78231 
…mns (ormar-orm#852)

Adds `through_relation_nullable` and `through_reverse_relation_nullable`
parameters on `ormar.ManyToMany` so users can enforce NOT NULL on the
auto-generated FK columns of the through table. Defaults to True to
preserve existing behavior.

Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>
@collerek collerek force-pushed the many-to-many-nullable-columns branch from ccbd159 to 0f78231 Compare April 22, 2026 17:51
@collerek @claude
test(relations): keep M2M through FK names under MySQL's 64-char limit
d223511 
Use `through_foreign_key_name` / `through_reverse_foreign_key_name` on
the test models to override the auto-generated constraint names that
otherwise blow past MySQL's identifier length cap.

Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>
@collerek collerek merged commit 077bcc5 into ormar-orm:master Apr 22, 2026
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@nikelborm @collerek