How to create a valid JSON example from Avro Schema?

Question

Got a fairly complicated Avro schema (which I can not modify).

Trying to mock JSON example in java:

GenericRecord genericRecord = AvroUtil.jsonToGenericRecord(jsonData, avroSchema);

It keeps failing:

Exception in thread "main" org.apache.avro.AvroTypeException: Expected start-union. Got VALUE_STRING

Is there e.g. online tool that will provide example of JSON data for any given Avro schema? (so that it can match correctly)

Tried mocking JSON data for hours and still no success..

Answer 1

You can create random data using trevni dependency and test scope. Here you have a sample code

import org.apache.avro.Schema;
import org.apache.trevni.avro.RandomData;

import java.util.Iterator;

public class JSONExample {
    public static void main(String [] args){
        Schema schema = new Schema.Parser().parse("{\n" +
                "     \"type\": \"record\",\n" +
                "     \"namespace\": \"com.acme\",\n" +
                "     \"name\": \"Test\",\n" +
                "     \"fields\": [\n" +
                "       { \"name\": \"name\", \"type\": \"string\" },\n" +
                "       { \"name\": \"age\", \"type\": \"int\" },\n" +
                "       { \"name\": \"sex\", \"type\": \"string\" },\n" +
                "       { \"name\": \"active\", \"type\": \"boolean\" }\n" +
                "     ]\n" +
                "}");

        Iterator<Object> it = new RandomData(schema, 1).iterator();
        System.out.println(it.next());
    }
}

output

{"name": "cjnyvbmetf", "age": -1757126879, "sex": "", "active": false}

maven dependencies

<dependencies>
    <dependency>
        <groupId>org.apache.avro</groupId>
        <artifactId>avro</artifactId>
        <version>1.8.2</version>
    </dependency>
    <dependency>
        <groupId>org.apache.avro</groupId>
        <artifactId>trevni-core</artifactId>
        <classifier>tests</classifier>
        <version>1.8.2</version>
    </dependency>
    <dependency>
        <groupId>org.apache.avro</groupId>
        <artifactId>trevni-avro</artifactId>
        <classifier>tests</classifier>
        <version>1.8.2</version>
    </dependency>
</dependencies>

Answer 2

You need to import below packages

compile "org.apache.avro:avro:1.8.2"
compile "org.apache.avro:avro-tools:1.8.2"
compile "org.apache.avro:trevni-core:1.8.2"
compile "org.apache.avro:trevni-avro:1.8.2"