validator tags used in JSF

validator tags used in JSF

In JavaServer Faces (JSF), validator tags are components used to validate user input on forms, ensuring data integrity and accuracy before processing. These tags are essential for implementing validation logic without custom Java code. Here’s an explanation followed by a Java example illustrating some validator tags used in JSF:

validator tags used in JSF

Explanation

  • 1.  <f:validateLength>:
    • Purpose:  Validates the length of a string input against specified minimum and maximum values.
    • Attributes:  minimum and maximum specify the allowed length range.
    • Example:  
      • <h:inputText id=”username” value=”{userBean.username}” required=”true”>
        • <f:validateLength minimum=”3″ maximum=”10″ />
        • </h:inputText>
  • 2.  <f:validateDoubleRange>:
    • Purpose:  Ensures that a double-precision floating-point number falls within a specified range.
    • Attributes:  minimum and maximum define the range of acceptable values.
    • Example:  
      • <h:inputText id=”price” value=”{productBean.price}” required=”true”>
      • <f:validateDoubleRange minimum=”0.01″ maximum=”1000.00″ />                   </h:inputText>
  • 3.  <f:validateRegex>:
    • Purpose:  Validates input against a regular expression pattern.
    • Attributes:  pattern specifies the regular expression pattern to match against.
    • Example:  
      • <h:inputText id=”email” value=”{userBean.email}” required=”true”>
      • <f:validateRegex pattern=”^[a-zA-Z0-9._%+-]+@[a-zA-Z0-9.-]+\.[a-zA-Z]{2,}$” />
      • </h:inputText>
  • 4.  <f:validateLongRange>:
    • Purpose:  Validates that a long integer falls within a specified range.
    • Attributes:  minimum and maximum define the acceptable range of values.
    • Example:
      • <h:inputText id=”quantity” value=”{orderBean.quantity}” required=”true”>
      • <f:validateLongRange minimum=”1″ maximum=”100″ />
      • </h:inputText>
  • 5.  <f:validateRequired>:
    • Purpose:  Checks that a required input field is not empty.
    • Attributes:  None required; it simply ensures that the associated input component has a non-empty value.
    • Example:
      • <h:inputText id=”username” value=”{userBean.username}” required=”true”>
      • <f:validateRequired />
      • </h:inputText>

Java Example

Here’s an example demonstrating the use of validator tags in JSF:

Managed Bean (UserBean.java)
java
package com.example.beans;

import javax.faces.bean.ManagedBean;
import javax.faces.bean.RequestScoped;

@ManagedBean
@RequestScoped
public class UserBean {

    private String username;
    private String email;

    // Getters and setters for username and email
    public String getUsername() {
        return username;
    }

    public void setUsername(String username) {
        this.username = username;
    }

    public String getEmail() {
        return email;
    }

    public void setEmail(String email) {
        this.email = email;
    }
}

JSF Page (userForm.xhtml)
xml
<!DOCTYPE html>
<html xmlns="http://www.w3.org/1999/xhtml"
      xmlns:h="http://xmlns.jcp.org/jsf/html"
      xmlns:f="http://xmlns.jcp.org/jsf/core">

<h:head>
    <title>User Registration Form</title>
</h:head>
<h:body>
    <h3>User Registration</h3>

    <h:form>
        <p>Username: <h:inputText id="username" value="{userBean.username}" required="true">
                      <f:validateLength minimum="3" maximum="10" />
                    </h:inputText>
        </p>
        <p>Email: <h:inputText id="email" value="{userBean.email}" required="true">
                   <f:validateRegex pattern="^[a-zA-Z0-9._%+-]+@[a-zA-Z0-9.-]+\.[a-zA-Z]{2,}$" />
                 </h:inputText>
        </p>

        <h:commandButton value="Register" action="{userBean.registerUser}" />
    </h:form>
</h:body>
</html>

Explanation of Example

  • Managed Bean (UserBean.java):
    • Defines UserBean as a managed bean with @ManagedBean annotation and @RequestScoped scope.
    • Includes properties username and email with corresponding getter and setter methods for handling user input.
  • JSF Page (userForm.xhtml):
    • Implements a user registration form using <h:form> to encapsulate input components and submission logic.
    • Utilizes <h:inputText> components for capturing username and email inputs, with associated validator tags (<f:validateLength>, <f:validateRegex>).
    • Includes a <h:commandButton> to trigger the registerUser method in UserBean upon form submission.

Summary

Validator tags in JSF such as <f:validateLength>, <f:validateDoubleRange>, <f:validateRegex>, <f:validateLongRange>, and <f:validateRequired> play crucial roles in validating user input on forms, ensuring data integrity and accuracy before processing. By utilizing these tags effectively, developers can enhance application reliability and user experience by preventing invalid data submissions. Understanding and implementing validator tags in JSF applications contribute to building robust and user-friendly web applications.