Ensure one property is not empty in JSON schema

Question

For the given schema below, is it possible to ensure that at least one property contains a value (ie, minLength is 1):

{
    "$schema": "http://json-schema.org/draft-04/schema#",
    "type": "object",
    "properties": {
        "fundRaiseId": {
            "type": "string"
        },
        "productTypeId": {
            "type": "string"
        },
        "businessLineId": {
            "type": "string"
        }
    }
}

So this would pass validation:

{
 "fundRaiseId": "x"
}

And this would fail as no values are present:

{
  "fundRaiseId": "",
  "productTypeId": "",
  "businessLineId": ""
}

score 22 · Accepted Answer · answered Jul 20 '16 at 10:23

I would try something like

{
    "allOf": [{
        "type": "object",
        "properties": {
            "fundRaiseId": {
                "type": "string"
            },
            "productTypeId": {
                "type": "string"
            },
            "businessLineId": {
                "type": "string"
            }
        }
    }, {
        "anyOf": [{
            "properties": {
                "fundRaiseId": {
                    "$ref": "#/definitions/nonEmptyString"
                }
            }
        }, {
            "properties": {
                "productTypeId": {
                    "$ref": "#/definitions/nonEmptyString"
                }
            }
        }, {
            "properties": {
                "businessLineId": {
                    "$ref": "#/definitions/nonEmptyString"
                }
            }
        }]
    }],
    "definitions": {
        "nonEmptyString": {
            "type": "string",
            "minLength": 1
        }
    }
}

Explanation: the JSON to be validated should conform to 2 root-level schemas, one is your original definition (3 string properties). The other one contains 3 additional sub-schemas, each defining one of your original properties as non-empty string. These are wrapped in an "anyOf" schema, so at least one of these should match, plus the original schema.

Great idea, however, the following is valid against the schema `{ }` whereas I need at least one property to contain a value as you have defined in your definition of `nonEmptyString` — Ric, Jul 20 '16 at 10:29
Then change the anyOf subschemas to eg. `{ "properties": { "fundRaiseId": { "$ref": "#/definitions/nonEmptyString" } }, "required" : ["fundRaiseId"] }` (so use the "required" keyword) — erosb, Jul 20 '16 at 10:30
I changed `anyOf` to `oneOf` and have got it working although all properties need to be present this more than suffices. — Ric, Jul 20 '16 at 12:14

score 21 · Answer 2 · answered Jul 21 '16 at 07:04

Is it a requirement that you allow the values to be empty? You can write a much cleaner schema if you requiring that all the strings are non-empty.

{
    "$schema": "http://json-schema.org/draft-04/schema#",
    "type": "object",
    "properties": {
        "fundRaiseId": { "$ref": "#/definitions/non-empty-string" },
        "productTypeId": { "$ref": "#/definitions/non-empty-string" },
        "businessLineId": { "$ref": "#/definitions/non-empty-string" }
    },
    "anyOf": [
        { "required": ["fundRaiseId"] },
        { "required": ["productTypeId"] },
        { "required": ["businessLineId"] }
    ],
    "definitions": {
        "non-empty-string": {
            "type": "string",
            "minLength": 1
        },
    }
}

this will still take in string with multiple spaces – Mohit Kalra Aug 27 '21 at 02:16 — Mohit Kalra, Aug 27 '21 at 02:16

Ensure one property is not empty in JSON schema

2 Answers2