My Journey to Validate Muhammad Saqib Sarwar [email_address]

1.To share my experience(thought process) of choosing a Validator framework. 2.To deliver basic knowledge of my chosen tool. Basic Goals Muhammad Saqib Sarwar [email_address]

New Change Arrived in current project DB Fields From 11 to 137 Account [54 Fields] Customer [74 Fields] Customer_account[9 Fields] So Big Change on Message Validations For: Create an Account Message Total: 46 Fields 14 Mandatory Fields 13 have length checks 5 have pattern checks others if exist should be validated too …. How I felt the need ? Simply Means a huge collection of if-else statements Muhammad Saqib Sarwar [email_address]

New Change Arrived in current project

DB Fields From 11 to 137

Account [54 Fields] Customer [74 Fields] Customer_account[9 Fields]

So Big Change on Message Validations

For: Create an Account Message

Total: 46 Fields

14 Mandatory Fields

13 have length checks

5 have pattern checks

others if exist should be validated too ….

1 st I written required if-else statements. BUT Soon I Found Myself In huge Mess ..  How I felt the need ? Muhammad Saqib Sarwar [email_address]

1 st I written required if-else statements.

BUT Soon

I Found

Myself

In huge

Mess .. 

Asked the BOSS Google “how to avoid too many if-else” Placed Question on JavaRanch Consulted with Colleagues Surprised ! Business layer validation frameworks exist in java world I only know them as presentation layer validator. What I did next … Muhammad Saqib Sarwar [email_address]

Asked the BOSS

Google “how to avoid too many if-else”

Placed Question on JavaRanch

Consulted with Colleagues

Surprised !

Business layer validation frameworks

exist in java world

I only know them as presentation

layer validator.

There are many available like Spring’s own validation Commons Validator JaValid Hibernate Validator (My Chosed One) And many more … Now the Question is Which one to use ? So I Sorted Few Priorities It should Solves the problem It should have Short learning curve Which one to use ..? Muhammad Saqib Sarwar [email_address]

There are many available like

Spring’s own validation

Commons Validator

JaValid

Hibernate Validator (My Chosed One)

And many more …

Now the Question is

Which one to use ?

So I Sorted Few Priorities

It should Solves the problem

It should have Short learning curve

First I looked at Validation in Spring 2.0.8 (as we already using it) Two Parts in the Validation Package Validator Interface Implementation DataBinder Primarily used in Spring-MVC framework Have to implement complete validation logic in validate() method Separate Validator for each entity Not fallow any standard (like few emerging in the market) Validation in Spring 2.0.8 Muhammad Saqib Sarwar [email_address]

First I looked at Validation in Spring 2.0.8 (as we already using it)

Two Parts in the Validation Package

Validator Interface Implementation

DataBinder

Primarily used in Spring-MVC framework

Have to implement complete validation logic in validate() method

Separate Validator for each entity

Not fallow any standard (like few emerging in the market)

Validation of JavaBeans based on an xml file Provides two distinct sets of functionality A configurable (typically XML) validation engine Reusable "primitive" validation methods Steps Create XML file Instantiate Validator class (org.apache.commons.validator.Validator) Add Resources (JavaBean,Locale) Call Validator’s validate method Evaluate Results Commons Validator Muhammad Saqib Sarwar [email_address]

Validation of JavaBeans based on an xml file

Provides two distinct sets of functionality

A configurable (typically XML) validation engine

Reusable "primitive" validation methods

Steps

Create XML file

Instantiate Validator class (org.apache.commons.validator.Validator)

Add Resources (JavaBean,Locale)

Call Validator’s validate method

Evaluate Results

Heavily depends on XML Manual evaluation of errors [  ] No default error messages Lengthy validation code Fallow No Standard Commons Validator Muhammad Saqib Sarwar [email_address]

Heavily depends on XML

Manual evaluation of errors [  ]

No default error messages

Lengthy validation code

Fallow No Standard

I want something easier than XML so searched for Annotation based bean validation frameworks and found JaValid.org It is an Annotations based bean validation framework Could be used standalone Provides full integration with Spring, JSF, Facelets and DB Customizable and Extensible Built in annotations for basic validations Well elaborated documentation Well documented source code Muhammad Saqib Sarwar [email_address]

I want something easier than XML so searched for Annotation based bean validation frameworks and found JaValid.org

It is an Annotations based bean validation framework

Could be used standalone

Provides full integration with Spring, JSF, Facelets and DB

Customizable and Extensible

Built in annotations for basic validations

Well elaborated documentation

Well documented source code

Annotate Bean’s Properties/(getter Methods) Instantiate Validator implementation Pass bean instance to Validator Validator returns List<ValidationMessage> Steps to use JaValid Muhammad Saqib Sarwar [email_address]

Annotate Bean’s Properties/(getter Methods)

Instantiate Validator implementation

Pass bean instance to Validator

Validator returns List<ValidationMessage>

only few built in annotation constraints building new constraints are little lengthier use XML configuration file to know about annotation classes and their related validator classes. error messages are hard coded ValidationMessage object is not customizable does not fallow any standard for validation Few disadvantages of JaValid ! Good Solution but not as simple and easy as hibernate validator Muhammad Saqib Sarwar [email_address]

only few built in annotation constraints

building new constraints are little lengthier

use XML configuration file to know about annotation classes and their related validator classes.

error messages are hard coded

ValidationMessage object is not customizable

does not fallow any standard for validation

Annotations based bean validation framework Aims to provide implementation of the emerging standard (JSR - 303 Bean Validation) Purely intended for multi-layered data validation Constraints are expressed in a single place (model) Not limited to use with hibernate Can be used any where in application Can be used with any java persistence provider Hibernate Validator Muhammad Saqib Sarwar [email_address]

Annotations based bean validation framework

Aims to provide implementation of the emerging standard (JSR - 303 Bean Validation)

Purely intended for multi-layered data validation

Constraints are expressed in a single place (model)

Not limited to use with hibernate

Can be used any where in application

Can be used with any java persistence provider

Decent Collection of Built in Constraints @Length (min=,max=) @Max(value=) @Min(value=) @NotNull @NotEmpty @Past @Future @Size(min=, max=) Hibernate Validator @Pattern(regex=&quot;regexp”, flag=) @Range(min=, max=) @AssertFalse @AssertTrue @Valid @Email @CreditCardNumber @Digits @EAN Few more … Muhammad Saqib Sarwar [email_address]

Decent Collection of Built in Constraints

@Length (min=,max=)

@Max(value=)

@Min(value=)

@NotNull

@NotEmpty

@Past

@Future

@Size(min=, max=)

@Pattern(regex=&quot;regexp”, flag=)

@Range(min=, max=)

@AssertFalse

@AssertTrue

@Valid

@Email

@CreditCardNumber

@Digits

@EAN

Few more …

Error Messages Validator returns array of InvalidValue InvalidValue contains constraint violation information (bean, name, path, value etc) It also contains Error Description Message we can override Error Messages By Creating Own ValidatorMessages.properties we can embed constraint parameters in messages Hibernate Validator Muhammad Saqib Sarwar [email_address]

Error Messages

Validator returns array of InvalidValue

InvalidValue contains constraint violation information (bean, name, path, value etc)

It also contains Error Description Message

we can override Error Messages

By Creating Own ValidatorMessages.properties

we can embed constraint parameters in messages

Sample Code [Annotated Account Bean] /*--------- Simple Bean ---------------*/ public class Account { @NotEmpty @Length(min=10,max=100) private String accountTitle; @NotEmpty private String processingCode; // regular getters and setters methods } Hibernate Validator Muhammad Saqib Sarwar [email_address]

Validation Code: Account account = new Account(); account.setAccountTitle(&quot;Mobex Ltd&quot;); ClassValidator<Account> accountValidator = new ClassValidator<Account>(Account.class); InvalidValue[] validationMessages = accountValidator. getInvalidValues (account); for(InvalidValue msg:validationMessages) System.out.println(msg.getPropertyPath()+&quot;-&quot;+msg.getMessage()); OUTPUT accountTitle-length must be between 10 and 100 processingCode-may not be null or empty Hibernate Validator Muhammad Saqib Sarwar [email_address]

public class Account { @NotEmpty @Length(min=10,max=100) private String accountTitle; @NotEmpty private String processingCode; // regular getters and setters methods } Hibernate Validator Muhammad Saqib Sarwar [email_address]

public class Account { @NotEmpty @Length(min=10,max=100) private String accountTitle; @NotEmpty @ProcessingCode(code=IProcessingCode. CHECK_BALANCE) private String processingCode; // regular getters and setters methods } Hibernate Validator Muhammad Saqib Sarwar [email_address]

Steps For Writing Our Own Constraints Constraint Descriptor (annotation) Constraint Validator (implementation class) Hibernate Validator Muhammad Saqib Sarwar [email_address]

Steps For Writing Our Own Constraints

Constraint Descriptor (annotation)

Constraint Validator (implementation class)

Constraint Descriptor (annotation) @Documented @ValidatorClass(ProcessingCodeValidator. class) @Target({METHOD, FIELD}) @Retention(RUNTIME) public @interface ProcessingCode { String code(); String message() default &quot;Invalid Processing Code&quot;; } Hibernate Validator org.hibernate.validator.ValidatorClass Muhammad Saqib Sarwar [email_address]

Constraint Descriptor (annotation)

@Documented

@ValidatorClass(ProcessingCodeValidator. class)

@Target({METHOD, FIELD})

@Retention(RUNTIME)

public @interface ProcessingCode {

String code();

String message() default &quot;Invalid Processing Code&quot;;

}

2. Constraint Validator Implementation Class public class ProcessingCodeValidator implements Serializable, Validator<ProcessingCode> { private static final long serialVersionUID = 1146464976464879846L; private String code; public void initialize (ProcessingCode parameter) { code = parameter.code(); } public boolean isValid (Object value) { if ( value == null )return false; if (!( value instanceof String)) return false; String str = (String) value; if(str.equals(code)) return true; return false; } } Muhammad Saqib Sarwar [email_address]

Account account = new Account(); account.setAccountTitle(&quot;Mobex Ltd&quot;); account.setProcessingCode(IProcessingCode. CREDIT_ACCOUNT); ClassValidator<Account> accountValidator = new ClassValidator<Account>(Account.class); InvalidValue[] validationMessages = accountValidator.getInvalidValues(account); for(InvalidValue msg:validationMessages) System. out.println(msg.getPropertyPath()+&quot;-&quot;+msg.getMessage()); OUTPUT accountTitle-length must be between 10 and 100 processingCode-Invalid Processing Code Hibernate Validator Muhammad Saqib Sarwar [email_address]

Using the Validator Database Schema-Level Validation ORM Integration Hibernate event-based validation PreInsertEvent PreUpdateEvent Java Persistence event-based validation Application-level validation Presentation layer validation Hibernate Validator Muhammad Saqib Sarwar [email_address]

Using the Validator

Database Schema-Level Validation

ORM Integration

Hibernate event-based validation

PreInsertEvent

PreUpdateEvent

Java Persistence event-based validation

Application-level validation

Presentation layer validation

Benifits simplicity Avoid XML based configuration Could be learned in short time Could be implemented in minutes Constraints annotation could be applied to Property Getter method Bean Class Aims to Fallows a developing standard (JSR-303 Bean Validation) Fallows DRY Principle [multi-layered validation] etc [many more to explore] Muhammad Saqib Sarwar [email_address]

Benifits

simplicity

Avoid XML based configuration

Could be learned in short time

Could be implemented in minutes

Constraints annotation could be applied to

Property

Getter method

Bean Class

Aims to Fallows a developing standard (JSR-303 Bean Validation)

Fallows DRY Principle [multi-layered validation]

etc [many more to explore]

We Use Validation Framework To avoid series of messy if-else statements To Increase code readability To make code easily maintainable To avoid writing validation on multiple layers To increase productivity Summary Muhammad Saqib Sarwar [email_address]

We Use Validation Framework

To avoid series of messy if-else statements

To Increase code readability

To make code easily maintainable

To avoid writing validation on multiple layers

To increase productivity