JSON Validation with JSON Schema

JSON has became a de-facto standard for webservices, replacing XML web services. It has native support in web browser clients.

That makes JSON is the standard of choice for UI-oriented services. It has a good support on mobile devices. Also, it provides smaller data payload size compared to XML and it’s very sufficient for high-load systems as it saves a traffic. But what is for data validation? For XML web services there is a XML Schema. It comes ti mind, that similar standard for JSON should be called “JSON Schema”. And it really exists!

There are a number of libraries for working with JSON Schema, including validators, documentation generators and data processing.

For java, there is a library which implements JSON message validation: json-schema-validator. It uses jackson library as its’ core and can be used in any java environment.

Here is demo application project: json-schema-validator-demo

Code sample:

java

 1import com.fasterxml.jackson.databind.JsonNode;
 2import com.github.fge.jsonschema.main.JsonValidator;
 3import com.github.fge.jsonschema.main.JsonSchemaFactory;
 4import com.github.fge.jsonschema.core.report.ProcessingReport;
 5import com.github.fge.jsonschema.core.util.AsJson;
 6...
 7
 8JsonValidator VALIDATOR  = JsonSchemaFactory.byDefault().getValidator();
 9
10JsonNode schemaNode = ...
11JsonNode data = ...
12
13ProcessingReport report = VALIDATOR.validateUnchecked(schemaNode, data);
14
15final boolean success = report.isSuccess();
16
17final JsonNode reportAsJson = ((AsJson) report).asJson();

Demo applicaiton: https://json-schema-validator.herokuapp.com/