JSON schema - how to make an enum-dependent field required?

Question

I have a JSON schema (v7.0), in which I need to ensure that exactly the properties listed are present in the final formData.

For most cases, this can be solved using "additionalProperties": false and "minProperties": X, where X represents the #properties in an object (courtersy of this solution)

However, in some cases the number of properties is variable.

This is the case in below example, where a selection of "Manual update" (enum 2) in "sync" can result in the field "manual_date" being added. When "sync" is set to "Manual update", the "manual_date" property needs to be required - but otherwise it should not be required.

I tried implementing this via the "required" statement under dependencies, but I believe this is wrong as I get some very extensive error messages when testing it via a validator.

So in short: I'm looking for the correct way to make enum-dependent fields required in my JSON schema.

My schema:

{
  "type": "object",
  "properties": {
    "rtc": {
      "title": "REAL-TIME-CLOCK (RTC)",
      "type": "object",
      "properties": {
        "sync": {
          "title": "Time synchronization method",
          "type": "integer",
          "default": 1,
          "anyOf": [
            {
              "type": "integer",
              "title": "Retain current time",
              "enum": [
                1
              ]
            },
            {
              "type": "integer",
              "title": "Manual update",
              "enum": [
                2
              ]
            },
            {
              "type": "integer",
              "title": "Automatic update (requires WiFi)",
              "enum": [
                3
              ]
            }
          ]
        },
        "timezone": {
          "title": "Time zone (UTC−12 to UTC+14)",
          "type": "number",
          "default": 0,
          "minimum": -12,
          "maximum": 14
        },
        "adjustment": {
          "title": "Adjustment (-129600 to 129600 seconds)",
          "type": "number",
          "default": 0,
          "minimum": -129600,
          "maximum": 129600
        }
      },
      "dependencies": {
        "sync": {
          "oneOf": [
            {
              "properties": {
                "sync": {
                  "enum": [
                    1
                  ]
                }
              }
            },
            {
              "properties": {
                "sync": {
                  "enum": [
                    2
                  ]
                },
                "manual_date": {
                  "title": "Time (UTC) ",
                  "type": "string",
                  "format": "date-time"
                }
              },
              "required": [
                "manual_date"
              ]
            },
            {
              "properties": {
                "sync": {
                  "enum": [
                    3
                  ]
                }
              }
            }
          ]
        }
      },
      "additionalProperties": false,
      "patternProperties": {
        "manual_date": {}
      },
      "minProperties": 3
    }
  }
}

Martin Martin · Accepted Answer · 2019-03-15T11:53:24

Update: I did not find a direct solution to this. However, a partial solution can be done by using additionalProperties: false and minProperties: X in combination. This helps ensure that the right amount of fields - and only the right fields will be included.

JSON schema - how to make an enum-dependent field required?

1 Answers