A tool for validating structured data and providing metrics on data streams. It works primarily with Avro/JSON data for now but can be extended to support other schemas.
You can augment an existing Avro schema by including new tags that reference type-specific constraints. In the partial Person schema below we'd like to ensure that first name values are kept between 2 and 30 characters in length:
fields : {
"name": "firstname",
"type": "string",
"doc": "Person's first name",
"constraints" : [
{
"function" : "length",
"id" : "firstNameLength",
"args" : [
{ "name" : "min", "value" : "2"},
{ "name" : "max", "value" : "30"}
]
} ]
},
You can then use the modified schema to configure a validator that checks all firstname values and returns any violations found in a map keyed by paths to the offending field:
validator = new AvroValidator(Person.getClassSchema(), false);
Person p = newPerson(……); // deserialized from JSON/Avro
Map<Path, Collection<Violation>> issues = validator.validate(p);
if (issues.isEmpty()) return;
// else simple issuehandler that prints them out
for (Entry<Path,Collection<Violation>> errors : issues.entrySet()) {
System.err.println(……);
}
Like XML, as long as your schema is syntactically correct, Json parsers will ignore new tags leaving you free to fully document & constraint your schemas and ensure that everyone that references them is on the same page.
A full listing of the available constraints and how to write your own are listed in the /docs/manual.pdf