Conditionally Required Attributes in jsonSchema: Explained

JSON (JavaScript Object Notation) Schema is a powerful tool for validating JSON data. It allows developers to define the structure and validation rules for JSON data. One important feature of JSON Schema is the ability to set certain attributes as required. However, in some cases, you may want to set an attribute as required only under certain conditions. This is where conditionally required attributes come in.

What are Conditionally Required Attributes?

Conditionally Required Attributes are attributes that are required only under certain conditions. For example, consider a JSON object representing a person. The person may have a "middleName" attribute, but it should only be required if the person's "firstName" and "lastName" attributes are both present. In this case, "middleName" is a conditionally required attribute.

How to Define Conditionally Required Attributes in jsonSchema?

Defining conditionally required attributes in jsonSchema involves using the "if" and "then" keywords. The "if" keyword is used to specify the condition under which the attribute should be required, while the "then" keyword is used to specify the attribute as required.

{
  "type": "object",
  "properties": {
    "firstName": {
      "type": "string"
    },
    "lastName": {
      "type": "string"
    },
    "middleName": {
      "type": "string"
    }
  },
  "required": ["firstName", "lastName"],
  "if": {
    "properties": {
      "firstName": { "const": "John" },
      "lastName": { "const": "Doe" }
    }
  },
  "then": {
    "required": ["middleName"]
  }
}

In the example above, the "middleName" attribute is conditionally required. It is required only if the "firstName" and "lastName" attributes are both "John" and "Doe" respectively.

Conclusion

Conditionally Required Attributes in jsonSchema provide a powerful way to define validation rules for JSON data. By using the "if" and "then" keywords, developers can define attributes as required only under certain conditions. This can help to ensure that JSON data is structured correctly and meets the required validation rules.