fix(fetch): accept null for optional parameters#3982
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rohitg00 wants to merge 1 commit intomodelcontextprotocol:mainfrom
Open
fix(fetch): accept null for optional parameters#3982rohitg00 wants to merge 1 commit intomodelcontextprotocol:mainfrom
rohitg00 wants to merge 1 commit intomodelcontextprotocol:mainfrom
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Closes modelcontextprotocol#2035. Clients like LibreChat send explicit `null` for optional params instead of omitting them. The Fetch model declared `max_length: int`, `start_index: int`, and `raw: bool`, so Pydantic rejected `null` at the type-coercion step before field defaults could apply. Adds a `mode="before"` field_validator that maps `None` back to the field's declared default. Keeps field types as `int`/`bool`, preserves the `gt=0`/`lt=1_000_000`/`ge=0` validators on resolved values, and does not rely on falsy-coalescing (which would have replaced valid `start_index=0` or explicit `raw=false`). Adds 9 tests covering null handling, default preservation, explicit zero/false preservation, and validator behavior.
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Closes #2035.
Clients like LibreChat send explicit
nullfor optional Pydantic parameters. The Fetch model typed them asint/bool, so Pydantic rejectednullat type coercion before field defaults could apply.Fix
Adds a
mode="before"field_validator onmax_length,start_index, andrawthat mapsNoneto the field's declared default. Fields keep theirint/booltypes, validators (gt=0,lt=1_000_000,ge=0) continue to enforce on resolved values, and falsy-coalescing is avoided so validstart_index=0and explicitraw=falsepass through unchanged.Tests
9 new tests covering:
start_index=0,raw=false)Full suite: 29 passed, ruff clean, pyright 0 errors.
AI disclosure
Human-led, drafted with Claude Code assistance. I chose the validator pattern after reviewing closed PR #2631 (which used
orcoalescing that silently discards valid falsy values likestart_index=0). The fix was tested locally before opening the PR.