{
  "bsonType": "object",
  "required": ["uid", "fid", "create_time"],
  "permission": {
    "read": true,
    "create": "doc.uid == auth.uid || 'admin' in auth.role",
    "update": "doc.uid == auth.uid || 'admin' in auth.role",
    "delete": "doc.uid == auth.uid || 'admin' in auth.role"
  },
  "properties": {
    "_id": {
      "bsonType": "objectId",
      "description": "自动生成的文档ID"
    },
    "uid": {
      "bsonType": "string",
      "title": "用户标识",
      "foreignKey": "uni-id-users._id",
      "trim": "both",
      "minLength": 24,
      "maxLength": 24,
      "errorMessage": "用户ID必须为24位合法ObjectId"
    },
    "fid": {
      "bsonType": "string",
      "title": "关联对象ID",
	  "foreignKey": "uni-id-users._id",
      "trim": "both",
	  "minLength": 24,
	  "maxLength": 24,
      "errorMessage": "关联ID必须为24位合法ObjectId"
    },
    "create_time": {
      "bsonType": "timestamp",
      "title": "创建时间",
      "defaultValue": {
        "$env": "now"
      }
    }
  },
  "indexes": [
    {"uid": 1, "fid": 1}
  ]
}