{
  "id": "python/flask-sqlalchemy-integrity-error",
  "signature": "sqlalchemy.exc.IntegrityError: (sqlite3.IntegrityError) UNIQUE constraint failed: users.username",
  "signature_zh": "SQLAlchemy 完整性错误：(sqlite3.IntegrityError) 唯一约束失败：users.username",
  "regex": "sqlalchemy\\.exc\\.IntegrityError:\\ \\(sqlite3\\.IntegrityError\\)\\ UNIQUE\\ constraint\\ failed:\\ users\\.username",
  "domain": "python",
  "category": "data_error",
  "subcategory": null,
  "root_cause": "尝试插入重复的用户名，违反了数据库的唯一约束",
  "root_cause_type": "generic",
  "root_cause_zh": "尝试插入重复的用户名，违反了数据库的唯一约束",
  "versions": [
    {
      "version": "3.9",
      "introduced": null,
      "deprecated": null,
      "removed": null,
      "behavior_change": null,
      "status": "active"
    },
    {
      "version": "3.10",
      "introduced": null,
      "deprecated": null,
      "removed": null,
      "behavior_change": null,
      "status": "active"
    }
  ],
  "os_specific": {},
  "dead_ends": [
    {
      "action": "捕获异常后直接忽略",
      "why_fails": "用户不会收到错误提示，数据未保存",
      "fail_rate": 0.9,
      "condition": "",
      "sources": []
    },
    {
      "action": "删除唯一约束而不数据清洗",
      "why_fails": "可能导致数据混乱",
      "fail_rate": 0.7,
      "condition": "",
      "sources": []
    }
  ],
  "workarounds": [
    {
      "action": "在插入前检查用户名是否已存在",
      "success_rate": 0.9,
      "how": "if User.query.filter_by(username=username).first():\n    return '用户名已存在', 400",
      "condition": "",
      "sources": []
    },
    {
      "action": "使用 try-except 捕获并返回友好错误",
      "success_rate": 0.95,
      "how": "try:\n    db.session.add(user)\n    db.session.commit()\nexcept IntegrityError:\n    db.session.rollback()\n    return '用户名已存在', 400",
      "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": 0.86,
  "fix_success_rate": 0.8,
  "resolvable": "true",
  "first_seen": "2024-07-22",
  "last_confirmed": "2025-01-01",
  "last_updated": "2025-01-01",
  "evidence_count": 0,
  "tags": [],
  "locale": "en",
  "aliases": []
}