feat: Allow to automatically run group rules on primary key

[Oliver Borchert (borchero)]

Motivation

When using dataframely schemas as mixins, it is sometimes convenient to define rules in the mixins. Currently, it is not possible, however, to define group rules that dynamically apply to the primary key of the schema adopting the mixin.

Changes

• Allow to set group_by="primary_key" in the @dy.rule decorator to dynamically resolve to all primary key columns

[Copilot]

Pull request overview

This PR extends Dataframely’s @dy.rule group-rule functionality to support group_by="primary_key", allowing mixins (and other reusable schema components) to define group rules that automatically group by the adopting schema’s primary key.

Changes:

• Extend @dy.rule(group_by=...) to accept the sentinel value "primary_key" and resolve it to Schema.primary_key() at class creation time.
• Raise an ImplementationError when "primary_key" is requested but the schema has no primary key columns.
• Add tests covering single/composite primary keys, no-primary-key error behavior, and mixin behavior.

Reviewed changes

Copilot reviewed 2 out of 2 changed files in this pull request and generated 2 comments.

File	Description
dataframely/_rule.py	Adds "primary_key" sentinel support to group-rule creation and documents the new behavior.
tests/schema/test_rule_implementation.py	Adds test coverage for primary-key-based grouping, including mixin usage.

[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 100.00%. Comparing base (1527718) to head (c2106c6).
⚠️ Report is 1 commits behind head on main.

Additional details and impacted files

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  Coverage   100.00%   100.00%           
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  Files           54        54           
  Lines         3127      3133    +6     
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+ Hits          3127      3133    +6     

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