Validating a 1.1 station_status.json doesn't flag presence of incorrect 'num_bikes_available_types' attribute.

[richtaylor-ito]

When validating a v1.1 station_status.json which uses 'num_bike_available_types' in place of 'vehicles_types_available' (as per the 1.1 schema), the validator doesn't flag this.

An example of this can be seen in Bcycle's feed https://gbfs.bcycle.com/bcycle_lametro/gbfs.json :

{ is_returning: 1, is_renting: 1, is_installed: 1, num_docks_available: 23, num_bikes_available: 8, last_reported: 1635497046, num_bikes_available_types: { electric: 4, smart: 0, classic: 4 }, station_id: "bcycle_lametro_3005" }

[richtaylor-ito]

While GBFS does allow for extensions outside of the spec, extensions should be prefixed with an underscore, which would make it possible to distinguish them from mis-named or mis-used attributes.

[isabelle-dr]

Hi @richtaylor-ito, thanks for opening this issue!
It seems like this can be handled with additional properties.
Adding the following property in the Json Schemas will flag additional properties.

"additionalProperties": false

But this would flag the extensions outside the spec as well...
@PierrickP any thoughts on how to solve this problem?

[isabelle-dr]

After trying it with an online Json Schema Validator, using "additionalProperties": false works.
We would need to add it to all properties levels in order to flag additional fields in all levels of the JSON file.

Here is the modified station_status file that flags the additional field in Bcycle's feed:

station_status.json

{
  "$schema": "http://json-schema.org/draft-07/schema",
  "$id": "https://github.com/NABSA/gbfs/blob/master/gbfs.md#station_statusjson",
  "description":
    "Describes the capacity and rental availablility of the station",
  "type": "object",
  "properties": {
    "last_updated": {
      "description":
        "Last time the data in the feed was updated in POSIX time.",
      "type": "integer",
      "minimum": 1450155600
    },
    "ttl": {
      "description":
        "Number of seconds before the data in the feed will be updated again (0 if the data should always be refreshed).",
      "type": "integer",
      "minimum": 0
    },
    "version": {
      "description":
        "GBFS version number to which the feed conforms, according to the versioning framework (added in v1.1).",
      "type": "string",
      "const": "1.1"
    },
    "data": {
      "description":
        "Array that contains one object per station as defined below.",
      "type": "object",
      "properties": {
        "stations": {
          "type": "array",
          "items": {
            "type": "object",
            "properties": {
              "station_id": {
                "description": "Identifier of a station.",
                "type": "string"
              },
              "num_bikes_available": {
                "description":
                  "Number of vehicles of any type physically available for rental at the station.",
                "type": "number",
                "minimum": 0
              },
              "num_bikes_disabled": {
                "description":
                  "Number of disabled vehicles of any type at the station.",
                "type": "number",
                "minimum": 0
              },
              "num_docks_available": {
                "description":
                  "Number of functional docks physically at the station.",
                "type": "number",
                "minimum": 0
              },
              "num_docks_disabled": {
                "description":
                  "Number of empty but disabled docks at the station.",
                "type": "number",
                "minimum": 0
              },
              "is_installed": {
                "description": "Is the station currently on the street?",
                "type": "number",
                "minimum": 0,
                "maximum": 1
              },
              "is_renting": {
                "description": "Is the station currently renting vehicles?",
                "type": "number",
                "minimum": 0,
                "maximum": 1
              },
              "is_returning": {
                "description": "Is the station accepting vehicle returns?",
                "type": "number",
                "minimum": 0,
                "maximum": 1
              },
              "last_reported": {
                "description":
                  "The last time this station reported its status to the operator's backend.",
                "type": "number",
                "minimum": 1450155600
              }
            },
            "required": [
              "station_id",
              "num_bikes_available",
              "num_docks_available",
              "is_installed",
              "is_renting",
              "is_returning",
              "last_reported"
            ],
            "additionalProperties": false
          }
        }
      },
      "required": ["stations"],
    }
  },
  "required": ["last_updated", "ttl", "version", "data"],
}

[PierrickP]

Hello additionalProperties should work and i think there are a tricks with a regex to only accept underscore prefixed key

[richfab]

The spec

"Field names of extensions SHOULD be prefixed with an underscore (_) character." (reference)

Expected outcome:

The validator should return a WARNING when an additional property does not start with an underscore (_).

Potential solution described above by PierrickP:

1. Set the additionalProperties schema to false to reject additional properties (reference)
2. Set the patternProperties schema to {"^_": {}} to accept any property starting with underscore ("_") (reference)
3. Change the validator code to return a WARNING instead of an ERROR for this type of error.

JSON Schema example with additionalProperties and patternProperties:

station_status.json

{
  "$schema": "http://json-schema.org/draft-07/schema",
  "$id": "https://github.com/MobilityData/gbfs/blob/v3.0-RC2/gbfs.md#station_statusjson",
  "description":
    "Describes the capacity and rental availability of the station",
  "type": "object",
  "properties": {
    "last_updated": {
      "description":
        "Last time the data in the feed was updated in RFC3339 format.",
      "type": "string",
      "format": "date-time"
    },
    "ttl": {
      "description":
        "Number of seconds before the data in the feed will be updated again (0 if the data should always be refreshed).",
      "type": "integer",
      "minimum": 0
    },
    "version": {
      "description":
        "GBFS version number to which the feed conforms, according to the versioning framework (added in v1.1).",
      "type": "string",
      "enum": [
        "3.0-RC",
        "3.0-RC2",
        "3.0"
      ]
    },
    "data": {
      "description":
        "Array that contains one object per station as defined below.",
      "type": "object",
      "properties": {
        "stations": {
          "type": "array",
          "items": {
            "type": "object",
            "properties": {
              "station_id": {
                "description": "Identifier of a station.",
                "type": "string"
              },
              "num_vehicles_available": {
                "description":
                  "Number of vehicles of any type physically available for rental at the station.",
                "type": "integer",
                "minimum": 0
              },
              "vehicle_types_available": {
                "description":
                  "Array of objects displaying the total number of each vehicle type at the station (added in v2.1-RC).",
                "type": "array",
                "items": {
                  "type": "object",
                  "properties": {
                    "vehicle_type_id": {
                      "description":
                        "The vehicle_type_id of vehicle at the station (added in v2.1-RC).",
                      "type": "string"
                    },
                    "count": {
                      "description":
                        "A number representing the total amount of this vehicle type at the station (added in v2.1-RC).",
                      "type": "integer",
                      "minimum": 0
                    }
                  },
                  "required": ["vehicle_type_id", "count"]
                }
              },
              "num_vehicles_disabled": {
                "description":
                  "Number of disabled vehicles of any type at the station.",
                "type": "integer",
                "minimum": 0
              },
              "num_docks_available": {
                "description":
                  "Number of functional docks physically at the station.",
                "type": "integer",
                "minimum": 0
              },
              "num_docks_disabled": {
                "description":
                  "Number of empty but disabled docks at the station.",
                "type": "integer",
                "minimum": 0
              },
              "is_installed": {
                "description": "Is the station currently on the street?",
                "type": "boolean"
              },
              "is_renting": {
                "description": "Is the station currently renting vehicles?",
                "type": "boolean"
              },
              "is_returning": {
                "description": "Is the station accepting vehicle returns?",
                "type": "boolean"
              },
              "last_reported": {
                "description":
                  "The last time this station reported its status to the operator's backend in RFC3339 format.",
                "type": "string",
                "format": "date-time"
              },
              "vehicle_docks_available": {
                "description":
                  "Object displaying available docks by vehicle type (added in v2.1-RC).",
                "type": "array",
                "items": {
                  "type": "object",
                  "properties": {
                    "vehicle_type_ids": {
                      "description":
                        "An array of strings where each string represents a vehicle_type_id that is able to use a particular type of dock at the station (added in v2.1-RC).",
                      "type": "array",
                      "items": {
                        "type": "string"
                      }
                    },
                    "count": {
                      "description":
                        "A number representing the total number of available docks for the defined vehicle type (added in v2.1-RC).",
                      "type": "integer",
                      "minimum": 0
                    }
                  },
                  "required": ["vehicle_type_ids", "count"]
                }
              }
            },
            "required": [
              "station_id",
              "num_vehicles_available",
              "is_installed",
              "is_renting",
              "is_returning",
              "last_reported"
            ],
            "additionalProperties": false,
            "patternProperties": {"^_": {}}
          }
        }
      },
      "required": ["stations"]
    }
  },
  "required": ["last_updated", "ttl", "version", "data"]
}