[FIXED] How to bind list of category from database in jsp form

Issue

I have list of category in database and I want to bind those category in combobox: I know this is silly question and asked by so many times but I din't get answer as I want please do not down-vote or mark as duplicate.

Hare is my code: Controller class:

public String getCategoryList(Model model) {
        List<Category> categoryList = categoryService.getAllCategory();
        model.addAttribute("categoryList", categoryList);
        return "redirect:/manageProduct";

    }

Repository class:

@Override
    public List<Category> getAllCategory() {
        CriteriaQuery<Category> criteriaQuery = HibernateUtil.getSession(sessionFactory).getCriteriaBuilder()
                .createQuery(Category.class);
        criteriaQuery.from(Category.class);
        List<Category> categoryList = HibernateUtil.getSession(sessionFactory).createQuery(criteriaQuery)
                .getResultList();
        return categoryList;
    }

JSP page:

<label>Product Category</label> <select name="category"
                        class="browser-default custom-select mb-4">
                        <option value="" disabled selected>Choose Category</option>
                        <c:forEach items="${categoryList}" var="catList">
                            <option value="${catList.id}">${catList.categoryName}</option>
                        </c:forEach>
                    </select>

Where I am getting wrong please mark my error and try to answer in a simple way. Thank You.

Expected Result: populate list of category from database. Actual Result: Nothing get populated.

Solution

The problem is that you issue a redirect from the original request and therefore the model is not available when the view is rendered.

public String getCategoryList(Model model) {
    List<Category> categoryList = categoryService.getAllCategory();
    model.addAttribute("categoryList", categoryList);
    //return "redirect:/manageProduct"; 
    return "/manageProduct"; 
}

There is no need to redirect from a GET request so change as above and it should be fine.

If you do need to make request attributes available after a redirect (e.g. if following the Post/Redirect/Get pattern https://en.wikipedia.org/wiki/Post/Redirect/Get) then you can use Flash Attributes.

See here for more details:

https://docs.spring.io/spring/docs/current/spring-framework-reference/web.html#mvc-flash-attributes

https://dzone.com/articles/spring-mvc-flash-attributes

Answered By - Alan Hay