JSON data validation under JSON-schema

Question

I'm trying to validate some json data with ruby gem json-schema.

I have the following schema:

{
"$schema": "http://json-schema.org/draft-04/schema#",  
"title": "User",  
"description": "A User",  
"type": "object",  
"properties": {  
        "name": {
            "description": "The user name",
            "type": "string"
        },
        "e-mail": {
            "description": "The user e-mail",
            "type": "string"
        }  
},
"required": ["name", "e-mail"]    
}

and the following json data:

{
"name": "John Doe",
"e-mail": "john@doe.com",
"username": "johndoe"
}

And JSON::Validator.validate, using this data as input, returns true.

Shouldn't it be false since username is not specified on the schema?

Answer 1

You need to define additionalProperties in your JSON Schema and set it to false:

{
  "$schema": "http://json-schema.org/draft-04/schema#",  
  "title": "User",  
  "description": "A User",  
  "type": "object",  
  "properties": {  
    "name": {
      "description": "The user name",
      "type": "string"
    },
    "e-mail": {
      "description": "The user e-mail",
      "type": "string"
    }  
  },
  "required": ["name", "e-mail"],
  "additionalProperties": false
}

Now the validation should return false as expected:

require 'json'
require 'json-schema'

schema = JSON.load('...')
data = JSON.load('...')
JSON::Validator.validate(schema, data)
# => false