burakim/kaptan-field-checker

A Class Field Value Validation Library.

Kaptan Class Field Value Checker

"Kaptan" is a Turkish word that means captain.

Kaptan is a JAVA library that checks class fields in terms of input validation and verification. If it sees any variable value violation, it immediately throws FieldViolationException.

Getting Started

How Can I Get It

Gradle

compile 'me.yesilyurt.burak:kaptan-field-checker:1.1.0'

Maven

<dependency>
  <groupId>me.yesilyurt.burak</groupId>
  <artifactId>kaptan-field-checker</artifactId>
  <version>1.1.0</version>
  <type>pom</type>
</dependency>

How Can I Use It?

Let's say that you have a model (POJO) class whose name is User and it has username and password String fields. Let's assume that you don't want to get any null assignment for the username field and empty value assignment for the password field. You can write an input validation mechanism on your own or you can use Kaptan for checking your class fields. The below example shows a way to use Kaptan for it.

public class User {
    @MustBeNonNull
    private String username;
    @MustBeNonEmpty
    private String password;
    }

Did you realise @MustBeNonNull and @MustBeNonEmpty annotations?

Those are annotations that help Kaptan for understanding what your intentions and the structure of your class are. Since you put @MustBeNonNull above of your username field, Kaptan checks the username field if it is null. If it sees a null assignment in the username field, it throws a FieldViolationException to inform you.

Kaptan supports following annotations:

• @MustBeNonNull
• @MustBeNull
• @MustBeNonEmpty
• @MustBeEmpty
• @EnforceSizeConstraint(min=<value>, max=<value>)
• @EnforceRegexRule(<regex-string-value>)
• @EnforceIntervalConstraint(min=<value>, max=<value>)
• @MustContainsFollowingByteValues(values={,,..})
• @MustContainsFollowingDoubleValues(values={,,..})
• @MustContainsFollowingFloatValues(values={,,..})
• @MustContainsFollowingIntegerValues(values={,,..})
• @MustContainsFollowingLongValues(values={,,..})
• @MustContainsFollowingShortIntegerValues(values={,,..})
• @MustContainsFollowingStringValues(values={,,..})

To use Kaptan for checking your class fields

You can initiliaze a KaptanFieldChecker object, then you can continue by passing your model object (e.g. User class) into the check function of the KaptanFieldChecker object. Since it might throw a FieldViolationException, you should write a try&catch block and place the KaptanFieldChecker related code lines in your try block. You can find an example below.

try{
KaptanFieldChecker kaptanFieldChecker = new KaptanFieldChecker();
kaptanFieldChecker.check(targetObject);
}
catch(FieldViolationException e){
    // You can place your exception handling codes.
    e.printStackTrace();
}

What does Kaptan support

Kaptan supports primitives, enumerations, and data structures that are in the Java collection library, and Strings. If you want to Kaptan support your custom data structure, you can make it happen by implementing a KaptanField interface into your custom data structure.

License

This project is licensed under the MIT License - see the LICENSE file for details

Acknowledgments

This is an open-source project, we appreciate any contribution from contributors. If you want to improve Kaptan Class Field Input Checker, feel free to fork and create a pull request!

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