Spring MVC Form Validation - Creating Custom Validation Rule

By Known-Space -

Custom Validation



 Creating a custom validator entails us rolling out our own annotation and using it in our model to enforce the validation rules.

So, let's create our custom validator – which checks course code. The course code must starts with "LUV".
The New Annotation
Let's now create a validator class that enforces rules of our validation:

The validation class implements the ConstraintValidator interface and must implement the isValid method; it's in this method that we defined our validation rules.

Naturally, we're going with a simple validation rule here, to show how the validator works.
ConstraintValidator defines the logic to validate a given constraint for a given object. Implementations must comply with the following restriction:
  • the object must resolve to a non-parametrized type
  • generic parameters of the object must be unbounded wildcard types
Applying Validation Annotation
We defined a string field and annotated it with our custom annotation @CourseCode. In our controller we created our mappings and handled the error if any:

Comments

Post a Comment

Popular posts from this blog

Use @Initbinder in Spring MVC

By Known-Space -
Image
In this blog we will learn how to use @initbinder Annotation in Spring MVC. We will walk through a small example with help of a demo application. If you’re familiar with MVC architecture ,you must all be aware that controller is used for processing the web request and rendering the response to the View. Now,Initbinder comes into picture if you want to customize the request being sent to the controller.It is defined in the controller, helps in controlling and formatting each and every request that comes to it. This annotation is used with the methods which initializes  WebDataBinder  and works as a preprocessor for each request coming to the controller. InitBinder interaction with other Components Seems lot of gyaan right ! So,now to explain this let’s take an example. Consider we have student management portal for a school ,which manages the information of all the students present in the school.It has a feature for registering a student when he is admitted to the school. ...
Read more

Nginx

By Known-Space -
Image
What is a Web Server? A web server is software and hardware that uses  HTTP  (Hypertext Transfer Protocol) and other protocols to respond to  client  requests made over the World Wide Web. The main job of a web server is to display website content through storing, processing, and delivering webpages to users. Besides HTTP, web servers also support  SMTP  (Simple Mail Transfer Protocol) and FTP (File Transfer Protocol), used for email, file transfer, and storage. Web servers are  used in web hosting  or the hosting of data for websites and web-based applications -- or web applications. How do web servers work? Web server software is accessed through the domain names of websites and ensures the delivery of the site's content to the requesting user. The software side is also comprised of several components, with at least an HTTP server. The HTTP server is able to understand HTTP and URLs. As hardware, a web server is a computer that stores web s...
Read more

AWS Configuration For RDS(postgres),ElastiCache(Redis) with ElasticBean

By Known-Space -
AWS Configuration For RDS(postgres),ElastiCache(Redis) with ElasticBean RDS Database Creation Go to AWS Management Console and use Find Services to search for RDS Click Create database button Select PostgreSQL Check 'only enable options eligible for RDS Free Usage Tier' and click Next button Scroll down to Settings Form Set DB Instance identifier to multi-docker-postgres Set Master Username to postgres Set Master Password to postgres and confirm Click Next button Make sure VPC is set to Default VPC Scroll down to Database Options Set Database Name to fibvalues Scroll down and click Create Database button ElastiCache Redis Creation Go to AWS Management Console and use Find Services to search for ElastiCache Click Redis in sidebar Click the Create button Make sure Redis is set as Cluster Engine In Redis Settings form, set Name to multi-docker-redis Change Node type to 'cache.t2.micro' Change Number of re...
Read more

Different ways to Authenticate a Web Application

By Known-Space -
Image
  Authentication is common way to handle security for all applications. This is only way to answer the question “who you are?” to the application, when comes to stateless architecture or service oriented architecture we got lot of new concepts and technologies in the market. In this article we will learn how to handle authentication on RESTful APIs. Authentication: Lets start by listing the various ways through which we can achieve authentication, Cookie-Based authentication Token-Based authentication Third party access(OAuth, API-token) OpenId SAML Cookie based authentication  h a s been the default method for handling user authentication for a long time. From the below diagram you can clearly see the client posts the login credential to the server, server verifies the credential and creates session id which is stored in server(state-full) and returned to client via set-cookie. On subsequent request the session id from the cookie is verified in the server and the request get ...
Read more

The TRUE difference between [] and {{}} bindings in Angular

By Known-Space -
  One of the parts of Angular that most developers think they understand, but many don’t, is the true nature of [] and {{}} bindings. A fundamental lack of understanding of these bindings can become a major issue when working with templates and trying to get them to do exactly what you want. It can also be the cause of spending an unnecessary amount of hours trying to figure out a bug. So I’m going to run down exactly what these two bindings do, and what it is that many developers misunderstand about them. You’re probably familiar with the typical usage of {{}} bindings: <h1>{{title}}</h1> And you’re probably familiar with the typical usage of [] or property bindings: <img [src]="imgsrc"> But do you truly understand what each binding is doing? And why we use them in this situation? Many if not most developers simply know to use {{}} when putting text in an element, and [] for binding to properties. But have you ever wondered with reactive forms why the  form...
Read more

Why you should use BCrypt to hash passwords

By Known-Space -
In the online world, passwords play a critical role in keeping your data and other important information safe. For this reason, ensuring your passwords remain secure is critical. If not, the consequences can be catastrophic — think the Sony hacks of 2011. Hashed password solutions fall short Many password solutions simply are not good enough and put your data and resources at risk. Let’s take a look at a few examples. Plain text passwords As its name infers, a plain text password makes use of only letters. Should a hacker gain access to passwords such as these, they can easily pose as a user on your system. Often, plain text passwords are replicated across other logins as well, as users don’t want to have to remember multiple passwords for different sites or applications. Guess what? That just gives a hacker access to those applications as well. One way hash With a one-way hash password, a server does not store plain text passwords to authenticate a user. Here, a password...
Read more

CSRF Protection using Double Submitted Cookies

By Known-Space -
Image
Here we will look about the Double Submitted Cookies to CSRF protection. In Synchronizer Token the client and the server should wants to generate the token value. So this process is time consuming and get load the server. For reduce this kind of issues we are using double submitted cookies. We need java script to run double submitted cookies. For that the http flag should be off. Here we are sending two cookies through the http header and the http body. Then the server will validate these two cookies and if its same it will allow, if its not deny the request. In the client side (index.php) we create the session and store it in the cookie.After that create a token and store it in a new cookie. After that we shoud set the estimation of hidden token as "<? echo $token ?>" This will send the hidden token to server side when client click on login button. After that create a function to validate login in the server side Get the full code from here
Read more

CSRF Protection using Synchronizer Tokens

By Known-Space -
Image
What is cross site request forgery? Cross-Site Request Forgery (CSRF) is an attack that forces an end user to execute unwanted actions on a web application in which they're currently  authenticated. CSRF attacks specifically target state-changing requests,  not theft of data, since the attacker has no way to see the response to the forged request We can avoid these kind of attack (CSRF) by two ways 1. Synchronizer Tokens 2. Double submitted cookies Here we are considering on Synchronize Tokens. When we login, there will be a random number generated and stored on the client side and server side as well. So when the attacker creates the code he doesn't know the token value. So he can not create a code with the correct token value. Anyhow, if the victim clicks the link, that won't be harmful. because the verification will fail. For the first step we want to create the session in the client side (index.php). Then we want create a cookies and set session id to the cook...
Read more

Use of DispatcherServlet in Spring MVC Framework

By Known-Space -
Image
If you have worked with Spring MVC then you should know   what is a DispatcherServlet?   It's actually the heart of Spring MVC, precisely the C of MVC design pattern or Controller. Every single web request which is supposed to be processed by Spring MVC goes through DispatcherServlet. In general, it's an implementation of Front Controller Pattern which provides a single point of entry in your application. It handles all incoming requests. It is also the bridge between Java and Spring. Btw, the   DispatcherServlet   is like any other Servlet is declared in the web.xml with a URL pattern but the only special thing is that the URL pattern for dispatcher servlet is enough to map every single web request to DispathcherServlert. It is responsible for request handling by delegating requests to additional components of Spring MVC e.g. actual controller classes i.e. those which are annotated using   @Controller   or   @RestController   (in case of RESTful ...
Read more

Agile Methodology – Know the What and How?

By Known-Space -
Image
Gone are the days of using traditional software development models such as the Waterfall model. In today’s fast-paced IT world Agile is a new way forward. So in this blog, I will discuss What is Agile methodology. After reading this blog, your understanding of Agile will be crystal clear. Why do we need Agile methodology? Before Agile came into the picture, we had the Waterfall model of software development. The waterfall model can be defined as a sequential process in the development of a system or software that follows a top-down approach. This model was a straight forward and linear model. The waterfall model had various phases such as Requirements Gathering, Software Design, Implementation, Testing, Deployment, and Maintenance. This model however suffered a few drawbacks such as follows: This model was too time-consuming. Unless you complete a particular stage, you cannot proceed to the further stages. This model was suitable only for projects where requirements are stable. The wor...
Read more