Validate JSON against JSON Schema C#

Question

Is there a way to validate a JSON structure against a JSON schema for that structure? I have looked and found JSON.Net validate but this does not do what I want.

JSON.net does:

JsonSchema schema = JsonSchema.Parse(@"{
  'type': 'object',
  'properties': {
    'name': {'type':'string'},
    'hobbies': {'type': 'array'}
  }
}");

JObject person = JObject.Parse(@"{
  'name': 'James',
  'hobbies': ['.NET', 'LOLCATS']
}");

bool valid = person.IsValid(schema);
// true

This validates to true.

JsonSchema schema = JsonSchema.Parse(@"{
  'type': 'object',
  'properties': {
    'name': {'type':'string'},
    'hobbies': {'type': 'array'}
  }
}");

JObject person = JObject.Parse(@"{
  'surname': 2,
  'hobbies': ['.NET', 'LOLCATS']
}");

bool valid = person.IsValid(schema);

This also validates to true

JsonSchema schema = JsonSchema.Parse(@"{
  'type': 'object',
  'properties': {
    'name': {'type':'string'},
    'hobbies': {'type': 'array'}
  }
}");

JObject person = JObject.Parse(@"{
  'name': 2,
  'hobbies': ['.NET', 'LOLCATS']
}");

bool valid = person.IsValid(schema);

Only this validates to false.

Ideally I would like it to Validate that there are no fields aka name in there that shouldn't be in there aka surname.

Answer 1

I think that you just need to add

'additionalProperties': false

to your schema. This will stop unknown properties being provided.

So now your results will be:- True, False, False

test code....

void Main()
{
var schema = JsonSchema.Parse(
@"{
    'type': 'object',
    'properties': {
        'name': {'type':'string'},
        'hobbies': {'type': 'array'}
    },
    'additionalProperties': false
    }");

IsValid(JObject.Parse(
@"{
    'name': 'James',
    'hobbies': ['.NET', 'LOLCATS']
  }"), 
schema).Dump();

IsValid(JObject.Parse(
@"{
    'surname': 2,
    'hobbies': ['.NET', 'LOLCATS']
  }"), 
schema).Dump();

IsValid(JObject.Parse(
@"{
    'name': 2,
    'hobbies': ['.NET', 'LOLCATS']
  }"), 
schema).Dump();
}

public bool IsValid(JObject obj, JsonSchema schema)
{
    return obj.IsValid(schema);
}

output :-

True
False
False

You could also add "required":true to the fields that must be supplied that way you can return a message with details of missing/invalid fields:-

Property 'surname' has not been defined and the schema does not allow additional     properties. Line 2, position 19. 
Required properties are missing from object: name. 

Invalid type. Expected String but got Integer. Line 2, position 18.