JSON validator

A Java library that puts together a basic implementation of JSON codec and a generic declarative approach of validating properties of Java objects and their subitems via annotations.

Features

• You will never forget to explicitly set a serialized name for each property
• You will never get a sudden silent null after decoding in any of defined properties without explicit permission
• The whole classes tree will be checked recursively, including keys and values of any map or list
• You will get a verbose human-readable error, even if a property of sub-sub-sub...sub class of a map is invalid
• You will declare only rules which need to be checked, without any excessive code related to codec or Java
• Encoding and decoding obey common approaches like transient fields and has local-threaded optimization

Example

@SuppressWarnings({"InstanceVariableMayNotBeInitialized", "unused"})
public class ResponseError extends AbstractCheckableObject {
    // Allowed rules: ANY, NULL_OR_CHECKABLE, NOT_NULL, ZERO,
    // NON_NEGATIVE_INTEGER, POSITIVE_INTEGER, NON_EMPTY_STRING, TRUE, FALSE
    @CheckRule(NON_EMPTY_STRING)
    @SerializedName("reason")
    private String reason;

    @CheckRule(POSITIVE_INTEGER)
    @SerializedName("code")
    private Integer code;
}

// Allowed parents: AbstractCheckableMap, AbstractCheckableList, AbstractCheckableKeyValuePair
class ResponseErrors extends AbstractCheckableList<ResponseError> {}

public class Response extends AbstractCheckableObject {
    @CheckRule(NULL_OR_CHECKABLE)
    @SerializedName("errors")
    private ResponseErrors errors;
}

public class ResponseTest {
    @Rule
    public final ExpectedException e = ExpectedException.none();

    @Test
    public void testInvalidModel() throws Exception {
        e.expect(CheckException.class);
        e.expectMessage("Property 'errors.1.reason' of " +
                "com.mz.json.examples.model.Response{errors=[{reason=x, code=666}, {reason=, code=null}]} " +
                "is an empty string");
        decodeModel("{errors: [{reason: \"x\", code: 666}, {reason: \"\"}]}", Response.class);
    }
}

More examples

• Complex Model
• All the unit-tests

How to add the library to a project

1. Add the repo to GIT submodules:

   git submodule add -b master <repo>

2. Add to dependencies section of the build.gradle file:

   compile project(":json-validator")

3. Add to the settings.gradle file:

   include 'json-validator'

See also

• TODO list