Getting "Method not found: 'Boolean Newtonsoft.Json.Schema.SchemaExtensions.IsValid" in VS2019

Question

I've copied a sample from the site https://www.newtonsoft.com/jsonschema/help/html/ValidatingJson.htm:

using Newtonsoft.Json.Linq;
using Newtonsoft.Json.Schema;
...
string schemaJson = @"{
  'description': 'A person',
  'type': 'object',
  'properties': {
    'name': {'type': 'string'},
    'hobbies': {
      'type': 'array',
      'items': {'type': 'string'}
    }
  }
}";

JSchema schema = JSchema.Parse(schemaJson);

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

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

When I try to debug it in VS2019 I get an exception: "Method not found: 'Boolean Newtonsoft.Json.Schema.SchemaExtensions.IsValid"

I feel so stupid for asking, but what am I doing wrong?

Answer 1

等待大神答复