fix #244: remove @dataclass from MigrationError #266

Merged

Mark merged 1 commit from fix/mesh-seed-244-dataclass-migrationerror into master

2026-08-04 17:06:34 +00:00

Mark commented

2026-08-04 17:04:45 +00:00

Owner

Summary

Remove @dataclass decorator from MigrationError(Exception) in substrate/ledger/migrations.py:118.

Problem

MigrationError base class is decorated with @dataclass, which generates an __init__ that accepts only self. Subclasses (MigrationDriftError, UnknownMigrationError, ChecksumMismatchError) call super().__init__(message), which fails with:

TypeError: MigrationError.__init__() takes 1 positional argument but 2 were given

This breaks drift detection — db_migrate verify raises TypeError instead of MigrationDriftError.

Fix

Remove the @dataclass decorator. The subclasses set instance attributes manually already.

Verification

from substrate.ledger.migrations import MigrationDriftError
try:
    raise MigrationDriftError(checksum="abc", applied_sql="SELECT 1")
except MigrationDriftError:
    print("Fixed — drift detection works")

Closes #244

## Summary Remove `@dataclass` decorator from `MigrationError(Exception)` in `substrate/ledger/migrations.py:118`. ## Problem `MigrationError` base class is decorated with `@dataclass`, which generates an `__init__` that accepts only `self`. Subclasses (`MigrationDriftError`, `UnknownMigrationError`, `ChecksumMismatchError`) call `super().__init__(message)`, which fails with: ``` TypeError: MigrationError.__init__() takes 1 positional argument but 2 were given ``` This breaks drift detection — `db_migrate verify` raises TypeError instead of MigrationDriftError. ## Fix Remove the `@dataclass` decorator. The subclasses set instance attributes manually already. ## Verification ```python from substrate.ledger.migrations import MigrationDriftError try: raise MigrationDriftError(checksum="abc", applied_sql="SELECT 1") except MigrationDriftError: print("Fixed — drift detection works") ``` Closes #244

Mark added 1 commit

2026-08-04 17:04:46 +00:00

fix #244 : remove @dataclass from MigrationError to restore exception protocol

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07abae279d

The @dataclass decorator on MigrationError(Exception) generated an __init__
that accepted only self, breaking subclasses (MigrationDriftError,
UnknownMigrationError, ChecksumMismatchError) that call super().__init__(message).

This caused drift detection to raise TypeError instead of MigrationDriftError,
rendering the db_migrate verify CLI path broken.

Fix: remove the @dataclass decorator from line 118.