[SOLVED] Ajv — Use actual data in a schema

Ajv — Use actual data in a schema

    field_name: {
      type: "object",
      properties: {
        min: { type: "number", minimum: 0, maximum: 600 },
        max: { type: "number", minimum: 0, maximum: 600 },
      },
      required: ["min", "max"],
      additionalProperties: false,
    },

I am using ajv to validate my objects in node.

For the object above, how do I further specify that max must always be greater than min?

Solution

You can actually use the data provided for one property in the schema of another but you need to enable $data as an option when creating your Ajv instance:

note: $data is a JSON Pointer

const ajv = new Ajv({$data: true});

const validate = ajv.compile({
  type: 'object',
  properties: {
    min: {
      type: 'number',
      minimum: 0,
      exclusiveMaximum: 600
      // i.e. min >= 0 and min < 600
    },
    max: {
      type: 'number',
      exclusiveMinimum: {$data: "1/min"},
      maximum: 600
      // i.e. max > min and max <= 600
    }
  }
});


const test = (obj) => {
  const res = validate(obj);
  console.log(`{min: ${obj.min}, max: ${obj.max}} -> ${res}`);
  if (!res) console.log(validate.errors);
  return res;
}

test({min:   0, max: 500}); // true
test({min: 500, max:   0}); // false
test({min: 200, max: 200}); // false
test({min: 599, max: 600}); // true
test({min: 600, max: 600}); // false

<script src="https://cdnjs.cloudflare.com/ajax/libs/ajv/8.11.2/ajv7.bundle.js" integrity="sha512-gopWbU/o40XPlW4g/zJHfBUj1z9LKAWK6ZBFH5xiJHDDRRm8cXBo5UMLYTG5G42Pce8pBaWVNozLmvulanI3uQ==" crossorigin="anonymous" referrerpolicy="no-referrer"></script>
<script>
const {ajv7: Ajv} = window;
</script>