JSON Schema Draft 7 builder

This JSON Schema builder can be used to create JSON Schemas or even extending the builder i.e. see AsyncAPI builder.

The builder is very fluent and therefore it can be error pruning which methods which can be used when, check out Method combinations section for complet information about how to use and initilize the builder. Further the builder does not include a comprehensive check for nullpoint errors.

The following is an example usecase of the builder:

new JsonSchemaBuilder().
    object().
        property("id", SimpleType.INTEGER).
            minimum(0).
            description("Id of the streetlight.").parent().
        property("lumens", SimpleType.INTEGER).
            minimum(0).
            description("Light intensity measured in lumens.").parent().
        property("sentAt", SimpleType.STRING).
            format(StringFormat.DATE_TIME).
            description("Date and time when the message was sent.");

Method combinations

In below section an attempt is given to try an explain how to use the builder with the different method combinations which are available.

Initiating the root

Initiating the root is one of the first methods that is required to be called to prime the builder, any of the following methods can be used:

new JsonSchemaBuilder().
    object(). //Use an Object schema as root schema.
    nullSchema(). //Use a null type as a root schema.
    booleanSchema(). //Use a boolean type as a root schema.
    string(). //Use a string type as a root schema.
    array(). //Use an array type as a root schema.
    number(). //Use a number type as a root schema.
    integer(). //Use an integer type as a root schema.

Based on which root schema is used it opens up for a number of methods:

• Generic methods and special methods are always available no matter which root schema is choosen.
• Object schema are available to the object() root schema.
• nullSchema() and booleanSchema() root schemas does not have any extra methods.
• String schema are available to the string() root schema.
• Array schema are available to the array() root schema.
• Integer and Number schema are available to the number() and integer() root schema.

Special methods

build() are always available to return the root Schema object, which can then return the JSON string representation by calling toJson() i.e:

String jsonString = new JsonSchemaBuilder().booleanSchema().build().toJson();

parent() are used to return back to a previous schema. For example in the example usecase defined in the beginning of the readme parent() are used to move from the inner integer schemas to the root Object schema to define more properties.

new JsonSchemaBuilder().
    object().
        property("id", SimpleType.INTEGER).
            minimum(0).
            description("Id of the streetlight.").parent().
        property("lumens", SimpleType.INTEGER).
            minimum(0).
            description("Light intensity measured in lumens.").parent().
        property("sentAt", SimpleType.STRING).
            format(StringFormat.DATE_TIME).
            description("Date and time when the message was sent.");

When the SimpleType type parameter is seen it means a new schema object is created based on the type provided and is then used as the "active" schema, use parent() to return to the previous schema. I.e. for the object adding a property can be done by calling property(String propertyName, SimpleType type) which as shown below will create an Integer schema and use that as the current schema. Which then opens up for the use of string schema methods.

new JsonSchemaBuilder().
    object().
        property("lumens", SimpleType.INTEGER).
            minimum(0).
            description("Light intensity measured in lumens.")

Generic methods

Below is all the generic methods which available regardless of which root schema is choosen:

new JsonSchemaBuilder().
    object().
    nullSchema().
    booleanSchema().
    string().
    array().
    number().
    integer().
        title(String title).
        description(String description).
        elseDo().
        thenDo().
        ifCondition().
        oneOf(SimpleType type).
        allOf(SimpleType type).
        anyOf(SimpleType type);

Object schema

The following methods canbe used if the current schema is an object schema:

new JsonSchemaBuilder().
    object().
        property(String propertyName, SimpleType type).
        property(String propertyName, SimpleType type, boolean required).
        minProperties(int minProperties).
        maxProperties(int maxProperties);

Null schema

Does not have any extra methods.

Boolean schema

Does not have any extra methods.

String schema

The following methods canbe used if the current schema is a string schema:

new JsonSchemaBuilder().
    string().
        pattern(String pattern).
        contentMediaType(String contentMediaType).
        encoding(ContentEncoding encoding).
        format(StringFormat format).
        minLength(int minLength).
        maxLength(int maxLength);

Array schema

The following methods canbe used if the current schema is an array schema:

new JsonSchemaBuilder().
    array().
        allowAdditionalItems().
        onlyUniqueItems().
        minItems(int minItems).
        maxItems(int maxItems).
        item(SimpleType type).
        contain(SimpleType type);

Integer and Number schema

The following methods canbe used if the current schema is an integer and number schema:

new JsonSchemaBuilder().
    number().
    integer().
        minimum(double minimum).
        exclusiveMinimum(double exclusiveMinimum).
        maximum(double maximum).
        exclusiveMaximum(double exclusiveMaximum).
        multipleOf(double multipleOf);

What are not supported in the builder

Besides what the metamodel does not support, the following features are not supported in the builder:

• dependencies
• propertyNames
• anyOf, allOf, oneOf root schemas

JSON Schema draft 7 model

The underlying metamodel for JSON Schema draft 7 does not fully support all the different options available by the specification. The below section highlights what is not available

• References
• $schema
• Custom Format - besides Regular Expressions
• Property names
• Dependencies - Schema dependencies
• Pattern Properties