Generate Json Schema from POJO with a twist

Question

What I have:

I\'m generating a JSON schema from a pojo. My code to generate the schema looks like so:

ObjectMapper mapper = new ObjectMapper();
Titl         


        

Answer 1

It seems to not be possible using the instructions I found using databind. However I found another jackson module that seems to do the trick nicely. Oddly several of the objects are named the same.

TLDR: use objects from the org.codehaus.jackson.map package rather than the com.fasterxml.jackson.databind package. If you're following the instructions on this page then you're doing it wrong. Just use the jackson-mapper module instead.

Here's the code for future googlers:

private static String getJsonSchema(Class clazz) throws IOException {
    org.codehaus.jackson.map.ObjectMapper mapper = new ObjectMapper();
    //There are other configuration options you can set.  This is the one I needed.
    mapper.configure(SerializationConfig.Feature.WRITE_ENUMS_USING_TO_STRING, true);

    JsonSchema schema = mapper.generateJsonSchema(clazz);

    return mapper.writerWithDefaultPrettyPrinter().writeValueAsString(schema);
}

Answer 2

If someone comes here and wants to support the newest draft version in his code.

Look here for your preferred language: https://json-schema.org/implementations.html

Answer 3

Storme's answer references org.codehaus, which is an older version of jackson. The following is similar but uses fasterxml (newer version).

Pom:

<dependency>
    <groupId>com.fasterxml.jackson.core</groupId>
    <artifactId>jackson-core</artifactId>
    <version>2.7.1</version>
</dependency>
<dependency>
    <groupId>com.fasterxml.jackson.core</groupId>
    <artifactId>jackson-databind</artifactId>
    <version>2.7.1</version>
</dependency>
<dependency>
    <groupId>com.fasterxml.jackson.core</groupId>
    <artifactId>jackson-annotations</artifactId>
    <version>2.7.1</version>
</dependency>
<dependency>
    <groupId>com.fasterxml.jackson.module</groupId>
    <artifactId>jackson-module-jsonSchema</artifactId>
    <version>2.1.0</version>
</dependency>

Code:

import ...TargetClass;
import com.fasterxml.jackson.databind.ObjectMapper;
import com.fasterxml.jackson.databind.SerializationFeature;
import com.fasterxml.jackson.databind.jsonschema.JsonSchema;

import java.io.IOException;

public final class JsonSchemaGenerator {

    private JsonSchemaGenerator() { };

    public static void main(String[] args) throws IOException {
        System.out.println(JsonSchemaGenerator.getJsonSchema(TargetClass.class));
    }

    public static String getJsonSchema(Class clazz) throws IOException {
        ObjectMapper mapper = new ObjectMapper();
        mapper.configure(SerializationFeature.WRITE_ENUMS_USING_TO_STRING, true);
        JsonSchema schema = mapper.generateJsonSchema(clazz);
        return mapper.writerWithDefaultPrettyPrinter().writeValueAsString(schema);
    }

}