JSON schema does not explicitly add "additionProperties: false"

[crobinson42]

This validator:

v
  .object({
    id: v.string().required(),
    username: v.string(),
    nested: v.object({
      email: v.string(),
    }),
  })

Will produce this json-schema:

{
  type: 'object',
  properties: {
    id: { type: 'string' },
    username: { type: 'string' },
    nested: { type: 'object', properties: [Object] }
  },
  required: [ 'id' ]
}

The problem here is that JSON-schema validators like ajv infer if there is no additionalProperties: false then additional properties are allowed. This conflicts with the implementation of the ObjectValidator because if you want to allow additional properties you are required to chain .additional({ ... }) which should imply to the developer that when .additional({...}) is not used then to expect _additionalProperties: false_ in the json-schema output.

[crobinson42]

In case anyone comes here looking for a solution, I patch the JSON-schema programmatically using this function:

/**
 * This function will recursively search for JSON-schema { type: 'object' } and add { additionalProperties: false } to them.
 * @param data
 */
export function addAdditionalPropertiesFalse(data: any) {
  // If the current data is an object and not an array, proceed
  if (typeof data === 'object' && !Array.isArray(data)) {
    // Check if the object has the type property 'object'
    if (data.type === 'object') {
      // Add the additionalProperties property set to false
      data.additionalProperties = false;
    }

    // Iterate over each property of the object
    for (let key in data) {
      // If the property is an object or an array, recurse into it
      if (typeof data[key] === 'object') {
        addAdditionalPropertiesFalse(data[key]);
      }
    }
  } else if (Array.isArray(data)) {
    // Iterate over each item of the array
    for (let i = 0; i < data.length; i++) {
      // If the item is an object or an array, recurse into it
      if (typeof data[i] === 'object') {
        addAdditionalPropertiesFalse(data[i]);
      }
    }
  }
}

[crobinson42]

https://github.com/grantila/suretype/blob/master/lib/validators/object/validator.ts#L44C2-L69C3