Update User

### User story :
> User details successfully updated and stored in database.

### Pre-requisites:
- [ ] completed feature 1 - create user
- [ ] user dao ( update )
- [ ] user service ( update )

#### Validations:

- [ ] Form validator
* userId (less than or equal to 0)
* Name ( null, empty, pattern )
* password (null , empty, pattern )
* email(null , empty, pattern )
- [ ] Business Validation
* Check whether the userId exist

#### Messages:

* userId cannot be 0 or in negative
* Name cannot be null or empty
* Name should be match with the given pattern
* Password cannot be null or empty
* Password must contains at least 8 characters
* Password should match with the given pattern
* Email cannot be null or empty
* Email Should be match with the given pattern
* User not found

#### Flow:
> Invalid When a user's email is not in use or when the input provided does not meet the criteria, users arise.

```mermaid
graph TD;

A(UserService - int id, String name) --> B(Form Validation) -- Valid --> C(Business Validation)
B -- Invalid --> H(Validation Exception)
C -- Valid --> D(Argument Passed to UserDAO)
D --> F(Store Value in Database)
C -- Invalid --> E(Validation Exception)
```