{
  "id": "python/fastapi-query-param-list-error",
  "signature": "fastapi.exceptions.RequestValidationError: [{'loc': ['query', 'tags'], 'msg': 'value is not a valid list', 'type': 'type_error.list'}]",
  "signature_zh": "fastapi.exceptions.RequestValidationError: [{'loc': ['query', 'tags'], 'msg': '值不是有效的列表', 'type': 'type_error.list'}]",
  "regex": "fastapi\\.exceptions\\.RequestValidationError:\\ \\[\\{'loc':\\ \\['query',\\ 'tags'\\],\\ 'msg':\\ 'value\\ is\\ not\\ a\\ valid\\ list',\\ 'type':\\ 'type_error\\.list'\\}\\]",
  "domain": "python",
  "category": "type_error",
  "subcategory": null,
  "root_cause": "A query parameter is declared as List[str] but the client sends a single string without repeated parameters.",
  "root_cause_type": "generic",
  "root_cause_zh": "查询参数声明为 List[str]，但客户端发送单个字符串而未重复参数。",
  "versions": [
    {
      "version": "3.x",
      "introduced": null,
      "deprecated": null,
      "removed": null,
      "behavior_change": null,
      "status": "active"
    }
  ],
  "os_specific": {},
  "dead_ends": [
    {
      "action": "",
      "why_fails": "This is not standard and may break URL encoding.",
      "fail_rate": 0.5,
      "condition": "",
      "sources": []
    },
    {
      "action": "",
      "why_fails": "The validation still fails because the value is not a list.",
      "fail_rate": 0.7,
      "condition": "",
      "sources": []
    }
  ],
  "workarounds": [
    {
      "action": "",
      "success_rate": 1.0,
      "how": "Send multiple query parameters: /path?tags=a&tags=b",
      "condition": "",
      "sources": []
    },
    {
      "action": "",
      "success_rate": 0.8,
      "how": "Use a string and parse it: tags: str = Query(\"\"), then tags.split(\",\")",
      "condition": "",
      "sources": []
    }
  ],
  "workarounds_zh": [],
  "transition_graph": {
    "leads_to": [],
    "preceded_by": [],
    "frequently_confused_with": []
  },
  "official_doc_url": null,
  "official_doc_section": null,
  "error_code": null,
  "verification_tier": "ai_generated",
  "confidence": 0.89,
  "fix_success_rate": 0.8,
  "resolvable": "true",
  "first_seen": "2024-07-07",
  "last_confirmed": "2025-01-01",
  "last_updated": "2025-01-01",
  "evidence_count": 0,
  "tags": [],
  "locale": "en",
  "aliases": []
}