java-proto-validator

Usage

  public ProtobufValidator protoValidator() {
    return ProtobufValidator.createBuilder()
        .registerValidator(
            MessageValidator.createBuilder(User.getDescriptor())
                .addFieldConstraint("firstName", FieldConstraints.IS_SET)
                .addFieldConstraint("firstName", FieldConstraints.length(1, 50))
                .addFieldConstraint("lastName", FieldConstraints.IS_SET)
                .addFieldConstraint("lastName", FieldConstraints.length(1, 50))
                .addFieldConstraint("address", FieldConstraints.IS_SET)
                .addFieldConstraint("address", FieldConstraints.VALID)
                .addMessageConstraint(MessageConstraints.oneOfIsSet("phoneNumber"))
                .build())
        .registerValidator(
            MessageValidator.createBuilder(Address.getDescriptor())
                .addFieldConstraint("number", FieldConstraints.IS_SET)
                .addFieldConstraint("number", FieldConstraints.POSITIVE)
                .addFieldConstraint("name", FieldConstraints.IS_SET)
                .addFieldConstraint("name", FieldConstraints.length(1, 100))
                .addFieldConstraint("unit", FieldConstraints.POSITIVE)
                .build())
        .build();
  }

Constraints

There are Field level constraints that implement FieldConstraint and Message level constraints that implement MessageConstraint.

FieldConstraint

Used to declare a constraint that a field on a message must adhere to.

MessageConstraint

Used to declare a constraint that a message must adhere to.

Predefined Constraints

field.violations.AssertFalse.message     = must be false
field.violations.AssertTrue.message      = must be true
field.violations.Future.message          = must be a future date
field.violations.Max.message             = must be less than or equal to {max}
field.violations.Min.message             = must be greater than or equal to {min}
field.violations.Negative.message        = must be less than 0
field.violations.NegativeOrZero.message  = must be less than or equal to 0
field.violations.NotBlank.message        = must not be blank
field.violations.NotEmpty.message        = must not be empty
field.violations.IsSet.message           = must be set
field.violations.IsNotSet.message        = must not be set
field.violations.Past.message            = must be a past date
field.violations.Pattern.message         = must match '{regexp}'
field.violations.Positive.message        = must be greater than 0
field.violations.PositiveOrZero.message  = must be greater than or equal to 0
field.violations.Size.message            = size must be between {min} and {max}
field.violations.Length.message          = length must be between {min} and {max}
field.violations.HasKey.message          = must have key '{key}'

message.violations.OneOfIsSet.message    = one of {fields} must be set

Custom Constraints

Custom constraints can be created by implementing either FieldConstraint or MessageConstraint.

Some convenience abstract types can be extended which automatically performs the unwrapping of certain proto message types:

AbstractBooleanConstraint (auto unwraps BoolValue or null if not set)
AbstractNumberConstraint (auto unwraps DoubleValue, FloatValue, Int32Value, and Int64Value or null if not set)
AbstractStringConstraint (auto unwraps StringValue or null if not set)
AbstractTimestampConstraint (converts Timestamp to Instant or null if not set)
AbstractRepeatedConstraint (converts repeated field to List type)
AbstractMapConstraint (converts map field to Map type)

Custom Constraint Violation Messages

Messages for custom constraints can be defined in src/resources/ProtobufValidationMessages.properties. You may also override predefined constraint messages here.

Conditional Constraints

Conditionally applying a constraint is supported via the ApplyCondition interface.

Usage of Conditional Constraints

                .addFieldConstraint(
                    "buzzerCode",
                    FieldConstraints.IS_SET,
                    ApplyConditions.when(ApplyConditions.fieldIsTrue("hasBuzzer")))

Predefined ApplyConditions

constraint.condition.Expression.message  = when {expression}
constraint.condition.FieldIsTrue.message = when '{field}' is true
constraint.condition.FieldIsNotTrue.message = when '{field}' is not true
constraint.condition.FieldIsEqualTo.message = when '{field}' is equal to {value}

Custom ApplyConditions

Custom ApplyConditions can be created by implementing the ApplyCondition interface.

Some convenience abstract types can be extended to provide additional support:

AbstractBooleanFieldCondition (applies when a boolean field on the message has some value)
AbstractFieldCondition (applies when some field on the message has some value)

Violations

Constraint violations are determined by calling the following on ProtobufValidator:

public List<MessageViolation> validate(Message message);

Where MessageViolation looks like:

public class MessageViolation {

  private String path;
  private ErrorMessage error;
  private Optional<ConditionMessage> condition;
  private String defaultMessage;
  @Nullable private Object value;
  
  //Constructor and Getters ...

  public class ErrorMessage {
    private String code;
    private Map<String, Object> params;
  
    //Constructor and Getters ...
  }

  public class ConditionMessage {
    private String code;
    private Map<String, Object> params;
  
    //Constructor and Getters ...
    
  }
}

ro0sterjam/java-proto-validator