json_schema: {
      "$schema": "http://json-schema.org/draft-04/schema#",
      "type": "object",
      "properties": {
          "id": {
              "type": "number"
          },
          "rater": {
              "type": "object",
              "properties": {
                  "id": {
                      "type": "number"
                  },
                  "nickname": {
                      "type": "string"
                  },
                  "avatar": {
                      "type": ["string","null"]
                  },
                  "created_at": {
                      "type": "string"
                  },
                  "updated_at": {
                      "type": "string"
                  }
              },
              "required": [
                  "id",
                  "nickname",
                  "created_at",
                  "updated_at"
              ]
          },
          "value": {
              "type": "number"
          },
          "created_at": {
              "type": "string"
          },
          "updated_at": {
              "type": "string"
          }
      },
      "required": [
          "id",
          "rater",
          "value",
          "created_at",
          "updated_at"
      ]
  }
  