# fastapi.exceptions.RequestValidationError: 1 validation error for Request
query -> ids.0
  value is not a valid integer (type=type_error.integer)

- **ID:** `python/fastapi-query-param-list-parsing`
- **Domain:** python
- **Category:** data_error
- **Verification:** ai_generated
- **Fix Rate:** 80%

## Root Cause

Client sent repeated query parameters (ids=1&ids=2) but the endpoint declared ids: List[int] with an older FastAPI or used ids[]=1 which is not parsed.

## Version Compatibility

| Version | Status | Introduced | Deprecated |
|---------|--------|------------|------------|
| 3.x | active | — | — |

## Workarounds

1. **** (92% success)
   ```
   Declare ids: List[int] = Query(default=[]) and send ids=1&ids=2
   ```
2. **** (88% success)
   ```
   Use a JSON body model with ids: List[int] instead of query params
   ```

## Dead Ends

- **** — Loses validation and OpenAPI schema. (55% fail)
- **** — FastAPI does not strip brackets by default. (70% fail)