What Do We Want To Do? 🤔

Apply validation to the objects we receive at the endpoint controllers from clients.

What Is The First Solution That Comes To Mind? 🧠

it's simple, right? write functions that validate those objects.

Please meet the Javax validator.🥳

• It provides a set of annotations that are used with class fields.
• They act as constraints.
  • this field should not be null
  • this list should have a minimum size of 5
  • and many more...

How to do it?👀

For the object we want to validate

• We annotate the fields we want to validate with annotations from javax.validation.constraints

• Then, we annotate the parameter of the controller where we want to validate.

• We then have to catch the error thrown by the validator, and return a proper response to the user.

In conclusion✍️

• Imagine having an API with many endpoints that we need to validate. Which method would be better?
• The Validator.