JSON Schema equivalent of XSD maxOccurs-CodePudding

I have been searching around for a few hours now but I can't find examples for the query I have. I have an XSD schema (this is a really cut down version)

<xs:schema xmlns:xs="http://www.w3.org/2001/XMLSchema">
  <xs:element name="Transaction-Header">
    <xs:complexType>
      <xs:sequence>
        <xs:element name="Origin" type="xs:string" minOccurs="1" maxOccurs="1">
        </xs:element>
        <xs:element name="Type" type="xs:string" minOccurs="0" maxOccurs="1">
        </xs:element>
      </xs:sequence>
    </xs:complexType>
  </xs:element>
  <xs:element name="Transaction">
    <xs:complexType>
      <xs:sequence>
        <xs:element ref="Transaction-Header" minOccurs="1" maxOccurs="1" />
      </xs:sequence>
    </xs:complexType>
  </xs:element>
</xs:schema>

I am converting it to JSONSchema (it's a massive xsd) with a lot of success but what I can't seem to figure out is how to incorporate the minOccurs and maxOccurs restrictions.

Essentially, there should always only ever be 1 Transaction-Header i.e.

{
  "Transaction": {
    "Transaction-Header": {
      "Origin": "Origin",
      "Type": "Type"
    }
  }
}

Invalid:

{
  "Transaction": {
    "Transaction-Header": {
      "Origin": "Origin",
      "Type": "Type"
    },
    "Transaction-Header": {
      "Origin": "Origin",
      "Type": "Type"
    }
  }
}

I understand this can be done by using the array minItems / maxItems functionality, but these are really elements and not arrays and I don't really want to have to define them as such if possible.

Anyone know how (or even if) this is possible please?

CodePudding user response：

JSON Schema uses the JSON document model, and your second example is not valid JSON -- a property name cannot appear twice. You'll have to rename your properties so they are unique, or use an array.

If you use an array, you can use contains and minContains/maxContains to specify limitations on items in the array.