How to get Error message from REST service and show it at proper form field in java EE? - rest

Question

I made a Dynamic web project using Eclipse IDE. I made a simple web app for learning.
I also made a REST service (jersey implementation) which i am using for insert,update,delete and for listing records from mysql database.
Now i want that i've a registration form which has some fields. I want that before inserting the data into database using my REST service, the service should validate form data.
I searched a lot google. I understand how to validate data in my service. But i am not getting that how to show the error message to individual form field to client.
Is there any complete example of this which does not use maven and show me the whole working from submitting form to show the error messages.
Thanks in advance..please help me guys..

Answer 1

You should change your approach slightly to solve this problem and implement it in the following way:
First of all You should add validation mechanisms on the client side and send registration request only when this validation will be successful.
You will find form validation tutorial for AngularJS here:
https://docs.angularjs.org/guide/forms
http://www.ng-newsletter.com/posts/validations.html
and for jQuery here:
http://runnable.com/UZJ24Io3XEw2AABU/how-to-validate-forms-in-jquery-for-validation
Server should respond with propper HTTP statuses (with optional message). For example:
200 OK (or 201 Created) - when registration finished successfully;
400 Bad Request - when registration cannot be finished successfully;
So in Your actual use case:
User fills HTML form inputs;
Inserted data are validated on the client side;
When data are invalid, error message is shown in the propper place (individual form field);
When data are correct request is sent to the serwer;
Server application tries to insert supplied data to database;
If operation is finished properly, server will answer with 200 (or 201) status code. Registration is finished.
If operation is not finished properly, server will answer with 400. Client (AngularJS, jQuery, JS) will show error message.
Hopefully, my answer will help You. Ask if You need more explanation.