{
  "id": "python/pydantic-datetime-parsing",
  "signature": "pydantic_core._pydantic_core.ValidationError: 1 validation error for Event\nwhen\n  Input should be a valid datetime, invalid date separator, expected `-` [type=datetime_parsing, input_value='2024/01/15', input_type=str]",
  "signature_zh": "pydantic_core._pydantic_core.ValidationError：1 个验证错误（Event）\nwhen\n  输入应为有效的 datetime，日期分隔符无效，应为 '-' [type=datetime_parsing, input_value='2024/01/15', input_type=str]",
  "regex": "pydantic_core\\._pydantic_core\\.ValidationError:\\ 1\\ validation\\ error\\ for\\ Event\\\nwhen\\\n\\ \\ Input\\ should\\ be\\ a\\ valid\\ datetime,\\ invalid\\ date\\ separator,\\ expected\\ `\\-`\\ \\[type=datetime_parsing,\\ input_value='2024/01/15',\\ input_type=str\\]",
  "domain": "python",
  "category": "data_error",
  "subcategory": null,
  "root_cause": "The string uses slash separators that Pydantic v2's strict ISO parser rejects. It expects ISO 8601 with dashes.",
  "root_cause_type": "generic",
  "root_cause_zh": "字符串使用了斜杠分隔符，Pydantic v2 的严格 ISO 解析器拒绝该格式，它期望使用短横线的 ISO 8601 格式。",
  "versions": [
    {
      "version": "2.x",
      "introduced": null,
      "deprecated": null,
      "removed": null,
      "behavior_change": null,
      "status": "active"
    }
  ],
  "os_specific": {},
  "dead_ends": [
    {
      "action": "",
      "why_fails": "datetime_format only applies to date fields, not datetime, and won't accept time-less strings.",
      "fail_rate": 0.5,
      "condition": "",
      "sources": []
    },
    {
      "action": "",
      "why_fails": "Loses validation; downstream code must branch on type.",
      "fail_rate": 0.6,
      "condition": "",
      "sources": []
    },
    {
      "action": "",
      "why_fails": "Every call site must remember to convert; easy to miss and inconsistent.",
      "fail_rate": 0.45,
      "condition": "",
      "sources": []
    }
  ],
  "workarounds": [
    {
      "action": "",
      "success_rate": 0.9,
      "how": "from pydantic import BaseModel, field_validator\nfrom dateutil import parser\nclass Event(BaseModel):\n    when: 'datetime'\n    @field_validator('when', mode='before')\n    @classmethod\n    def parse(cls, v):\n        return parser.parse(v) if isinstance(v, str) else v",
      "condition": "",
      "sources": []
    },
    {
      "action": "",
      "success_rate": 0.85,
      "how": "import re\ns = re.sub(r'/', '-', '2024/01/15')\nEvent(when=s)",
      "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": 0.87,
  "fix_success_rate": 0.8,
  "resolvable": "true",
  "first_seen": "2024-07-21",
  "last_confirmed": "2025-01-01",
  "last_updated": "2025-01-01",
  "evidence_count": 0,
  "tags": [],
  "locale": "en",
  "aliases": []
}