The Regex Validator checks the provided String against the specified regular expression. It could be used in passwords, security keys, etc. Regular expression, or "Regex," is essentially a simple way to define a pattern of characters. Regex is frequently used in text mining, pattern recognition, and input validation. Regex turns off a lot of people because it initially appears to be unintelligible nonsense. However, those who are adept at using it seem unable to stop!
Regex Validator
A value entered into an input control is checked to see if it matches a regular expression pattern using the RegularExpressionValidator control. Using this type of validation, you can look for predictable character patterns, such as those in phone numbers, postal codes, and email addresses.
Run a RegExp against null to verify it (no need to know the data you want to test against upfront). It's broken if it returns an explicit false value (=== false). Even if it doesn't match anything, it is still valid otherwise.
Parameters of Regex Validator
Regex validator has fourdeclared arguments.
Example of Regex Validator
<validators>
<!-- Plain Validator Syntax -->
<validator type="regex">
<param name="fieldName">data</param>
<param name="expression">[A-Z,a-z,0-9]{5}</param>
<message>data must be alpha numeric of 5 digits</message>
</validator>
</validators>
This code shows the initialization of fieldname expression it's default message.
<validators>
<!-- Field Validator Syntax -->
<field name="data">
<field-validator type="regex">
<param name="expression">[A-Z,a-z,0-9]{5}</param>
<message>data must be alpha numeric of 5 digits</message>
</field-validator>
</field>
</validators>
This code shows the initialization of data regex it's default message.
The Complete Example of Regex Validator
Create index.jsp for Input
Utilizing the struts UI tags, this JSP website generates a form. It gets the user's name, password, and email address.
The execute function is overridden in this action class, which derives from the ActionSupport class.
RegisterAction.java
package com.javatpoint;
import com.opensymphony.xwork2.ActionSupport;
public class Register extends ActionSupport{
private String data;
public String getData() {
return data;
}
public void setData(String data) {
this.data = data;
}
public String execute(){
return "success";
}
}
Create the Validation File
In this case, the Validation is carried out utilising bundled validators.
Register-validation.xml
<?xml version="1.0" encoding="UTF-8"?>
<!DOCTYPE validators PUBLIC
"-//OpenSymphony Group//XWork Validator 1.0.2//EN"
"http://www.opensymphony.com/xwork/xwork-validator-1.0.2.dtd">
<validators>
<!--<field name="data">
<field-validator type="regex">
<param name="expression">[A-Z,a-z,0-9]{5}</param>
<message>data must be alpha numeric of 5 digits</message>
</field-validator>
</field>
-->
<field name="data">
<field-validator type="regex">
<param name="expression">[A,a][A-Z,a-z,0-9]{5}</param>
<message>data must be alpha numeric of 6 digits and starts with a or A</message>
</field-validator>
</field>
</validators>
Create struts.xml
This XML file specifies a workflow stack interceptor and a different outcome with the name input. jsonValidatorWorkflowStack.
It is a straightforward jsp file that shows the user's information.
welcome.jsp
<%@ taglib uri="/struts-tags" prefix="s" %>
Data is,<s:property value="data"/>
Frequently Asked Questions
How do I validate a pattern in RegEx?
Run a RegExp against null to verify it (no need to know the data you want to test against upfront). It's broken if it returns an explicit false value (=== false). Even if it doesn't match anything, it is still legitimate otherwise. The requirement to create your RegExp validator is thus unnecessary.
How do you check if a regular expression is valid or not?
To determine whether regEx is legitimate, use a new String (). matches(regEx) using try-catch. While this does achieve the desired outcome, Pattern. compile(regex) is less complicated (and exactly what would ultimately occur), and it has no added complexity.
What is Pythex?
You may quickly test your Python regular expressions with pythex. Test the example or try writing one. Match outcome: Match captures: cheat sheet for regular expressions.
How do you validate a form?
Basic Validation The form must first be reviewed to ensure that all required fields are filled in. All that would be necessary is a simple loop over the form's lots to check for data. Data Format Validation Next, the entered data must be examined for accuracy of form and content.
What does a * Do in RegEx?
The Operator for Matching Zero or More (*). This operator matches the pattern by iterating the most negligible preceding regular expression as often as required, up to and including zero. The symbol for this operator is "*." For instance, the character "o*" matches any string with 0–3 "o"s.
Conclusion
So that's the end of the article. regex validator
After reading about the regex validator, Are you interested in reading/exploring more themes on Validator?
Don't worry; Coding Ninjas has you covered.
However, if you want to give your work an edge over the competition, you might choose to enroll in one of our premium courses.
With our Coding Ninjas StudioGuided Path, you may learn about Data Structures & Algorithms, Competitive Programming, JavaScript, System Design, and more! If you want to put your coding skills to the test, check out the mock test series on Coding Ninjas Studio and participate in the contests! But if you've only recently started your schooling and are looking for answers to issues presented by digital titans like Amazon, Microsoft, Uber, and others. In this situation, you must consider the obstacles, interview experiences, and interview package as part of your placement preparations. If you find our blogs valuable and fascinating, please vote them up!
305+ registered