Validation is a wide known process in programming.
Say for example that you want to check whether the provided objects meet some specified rules before using them or persisting them into a database.
In spring for example, validation included and may be used at any stage of the flow of the application.
I tried to think out of the box, and imagine a customized object-validation using java, using annotation over fields of a class, or using specified list of criteria without annotating the class to validate.
To do so, I kind of created a repository on github to validate objects.
You can check it over here, any suggestions are welcome.
Start the repo if you like it, and if you want to contribute create a pull/merge request.
Examples of use :
1. Using annotations
Suppose we have a Person
class, and for all the instances, we want that the first name and the last name be assigned and not left null
:
class Person {
@Validation
private String name;
@Validation
private String lastName;
// .... other fields...
// .... getters and setters..
}
And we will create an instance, then we check if it is valid or not:
AnnotationValidator annotationValidator = new AnnotationValidator();
Person person = new Person();
person.setName("Mustapha");
person.setLastName("Belmokhtar");
boolean isValid = annotationValidator.checkValidation(person);
ValidationReport validationReportItem = annotationValidator.getValidationReport(person); // gives the details of each field
Result :
true
{lastName=|found=String:Belmokhtar, expected={!=null}:[], valid=true|, name=|found=String:Mustapha, expected={!=null}:[], valid=true|}
Validation by Operators:
class Person{
// ... others fields
@Validation(operator = Operator.GREATER_THAN, value = "18")
private int age;
// ... getters and setters ...
}
Person person = new Person();
person.setAge(20);
AnnotationValidator annotationValidator = AnnotationValidator.getInstance();
boolean isValid = annotationValidator.check(person);
ValidationReport validationReportItem = annotationValidator.getValidationReport(person);
Result :
true
{age=|found=Integer:20, expected={>}:[18], valid=true|}
2.Using criteria :
You can also perform validation over objects using Criteria
:
Student student = new Student();
CriteriaValidator criteriaValidator = CriteriaValidator.getInstance();
Criteria criteria = new Criteria();
criteria.setObject(student);
criteria.add(Criterion.of("name").is("mustapha"));
criteria.add(Criterion.of("address").notNull());
criteria.add(Criterion.of("age").greaterOrEquals(4));
criteria.add(Criterion.of("phoneNumber").matches("\\d{10}"));
student.setName("mustapha");
student.setAddress("wall street");
student.setAge(4);
student.setPhoneNumber("1234567890");
System.out.println(criteriaValidator.getValidationReport(criteria));
assertTrue(criteriaValidator.check(criteria));
Output :
address=|found=String:wall street, expected={!=null}:[null], valid=true|, phoneNumber=|found=String:1234567890, expected={REGEX}:[\d{10}], valid=true|, name=|found=String:mustapha, expected={==}:[mustapha], valid=true|, age=|found=Integer:4, expected={>=}:[4], valid=true|}
Criteria over complex Objects:
To perform validation by criteria over complex objects, you only have to specify the filed path of the wanted field, for example:
class Student {
// omittd fields for brievety
private Matters matters
//... getters and setters
}
//....
class Matters {
private double science;
private double maths;
private double languages;
//...
}
//...
Validation process:
CriteriaValidator criteriaValidator = CriteriaValidator.getInstance();
Criteria criteria = Criteria.of(student);
criteria.add(Criterion.of("matters.maths").lessThan(20.0));
Matters matters = new Matters();
matters.setMaths(19.99);
student.setMatters(matters);
System.out.println(criteriaValidator.getValidationReport(criteria));
assertTrue(criteriaValidator.check(criteria));
###### Output
{matters.maths=|found=Double:19.99, expected={<}:[20.0], valid=true|}
Validation overs arrays and collections:
class Book {
private int[] isbn;
private TreeSet<String> keywords;
// .. other fields
//.. getters and setters
}
Validation process:
Book book = new Book();
CriteriaValidator criteriaValidator = CriteriaValidator.getInstance();
Criteria criteria = Criteria.of(book);
criteria.add(Criterion.of("keywords").length(3));
criteria.add(Criterion.of("isbn").length(11));
int[] isbn = {1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11};
Set<String> keywords = new TreeSet<>();
keywords.add("science");
keywords.add("earth");
keywords.add("universe");
book.setKeywords(keywords);
book.setIsbn(isbn);
System.out.println(criteriaValidator.getValidationReport(criteria));
assertTrue(criteriaValidator.check(criteria));
Output
{keywords=|found=TreeSet:[earth, science, universe], expected={length}:[3], valid=true|, isbn=|found=int[]:[1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11], expected={length}:[11], valid=true|}
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