Update Product

### User story :

> Products deatils are successfully updated and stored in databse.

### Pre-requisites

- [ ] complete feature 1- create product
- [ ] Category model
- [ ] Category DAO(findAll,findById)
- [ ] Category service(findAll,findById)
- [ ] product table
- [ ] product DAO (update)
- [ ] product service ( update )

#### Validations:

- [ ] Form Validation
* product null or empty
* categoryId <= 0
* price <=0
* name ( null, empty, pattern )
* description ( null, empty )

- [ ] Business Validation
* Check whether the Category ID is available in the Category table.
* Check whether the Category exists.
* check whetehr the productId exists or not

#### Messages:

* invalid categoryId
* invalid product object
* price cannot be zero or negetive
* Name cannot be null or empty
* Name should be match with the given pattern
* Description cannot be null or empty
* categoryId is not available
* productId does not exists.

#### Flow:

> Invalid When a Product's name is not in use or when the input provided does not meet the criteria, categories arise.
```mermaid

graph TD;

A(ProductService - int id, String name) --> B(Form Validation) -- Valid --> C(Business Validation)

B -- Invalid --> G(Validation Exception)

C -- Valid --> D(Argument Passed to ProductDAO)

D --> E(Store Value in Database)

C -- Invalid --> F(Validation Exception)

```