Fix Field.error_messages type to allow dict and list values#2907
Merged
sloria merged 4 commits intomarshmallow-code:devfrom Mar 25, 2026
Merged
Fix Field.error_messages type to allow dict and list values#2907sloria merged 4 commits intomarshmallow-code:devfrom
sloria merged 4 commits intomarshmallow-code:devfrom
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The error_messages parameter on Field and its type annotation were typed as dict[str, str], but error messages can actually be dicts or lists (as used in tests and supported by ValidationError). This updates the type to dict[str, str | list | dict] via a new ErrorMessages type alias, fixing marshmallow-code#1636. Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>
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Summary
Closes #1636.
The
Field.error_messagesparameter was typed asdict[str, str], but error message values can be dicts or lists (e.g., the existing testtest_required_message_can_be_changedalready passes dict and list values). Themake_errormethod also already handles non-string values correctly.Changes
ErrorMessageValueandErrorMessagestype aliases totypes.pyfields.pyfromdict[str, str]totypes.ErrorMessages:_BaseFieldKwargs.error_messagesField.default_error_messagesField.__init__parametermessagesvariable in__init__Test plan
test_required_message_can_be_changedalready validates dict and list error message values