Spring框架NotReadablePropertyException问题求助：Bean属性'categoryName'不可读或getter方法无效

Hey there, let's figure out why you're hitting this error and fix it right away.

What's causing the issue? #

The error message spells it out clearly: Spring is trying to access the categoryName property on an ArrayList instead of your InvoiceCategory entity. Here's the root of the problem:

• When you load the listCategory page, you're adding a List to the Model with the key invoiceCategory.
• But your form uses modelAttribute="invoiceCategory", which expects a single InvoiceCategory object to bind form fields like categoryName to.
• Since an ArrayList doesn't have a getCategoryName() method, Spring throws that NotReadablePropertyException.

Let's fix this step by step #

1. Update your Controller's listCategory method

We need to separate the list of categories from the empty object used for the form. Rename the list's key and add a new empty InvoiceCategory for form binding:

@Controller 
@RequestMapping("/invoice") 
public class InvoiceController { 
    @Autowired 
    private InvoiceCategoryService invoiceCategoryService; 

    @GetMapping("/listCategory") 
    public String listCategory(Model theModel) { 
        // Rename the list to avoid conflict with the form object
        List<InvoiceCategory> invoiceCategories = invoiceCategoryService.getInvoiceCategory(); 
        theModel.addAttribute("invoiceCategories", invoiceCategories); 
        // Add an empty InvoiceCategory for the form
        theModel.addAttribute("newInvoiceCategory", new InvoiceCategory()); 
        return "add-invoice-category"; 
    } 

    @PostMapping("/saveCategory") 
    // Match the model attribute name to the form's key
    public String saveCategory(@ModelAttribute("newInvoiceCategory") InvoiceCategory theInvoiceCategory) { 
        invoiceCategoryService.saveInvoiceCategory(theInvoiceCategory); 
        // Redirect back to the category list (fixed the likely typo from /customer/list)
        return "redirect:/invoice/listCategory"; 
    } 
}

2. Adjust your JSP's list loop

Update the items attribute to use the new key for the category list:

<c:forEach var="tempInvoiceCategory" items="${invoiceCategories}"> 
 <tr> 
 <td>${tempInvoiceCategory.categoryName}</td> 
 <td> 
 <button type="button" class="btn btn-info">Edit</button> 
 <button type="button" class="btn btn-danger">Delete</button> 
 </td> 
 </tr> 
</c:forEach>

3. Fix the form's modelAttribute

Change the form's modelAttribute to point to the empty InvoiceCategory object we added:

<form:form class="forms-sample" action="saveCategory" modelAttribute="newInvoiceCategory" method="POST"> 
 <div class="form-group"> 
 <label>Nazwa Kategorii</label> 
 <form:input path="categoryName" type="text" class="form-control"/> 
 </div> 
 <button type="submit" class="btn btn-primary mr-2">Submit</button> 
</form:form>

Quick extra tips #

I renamed the saveCustomer method to saveCategory since it's handling category data—this just makes your code more readable and avoids confusion. Also, the original redirect was pointing to /customer/list, which I switched to /invoice/listCategory assuming that's where you want users to land after saving a category.

内容的提问来源于stack exchange，提问作者Adrian Drohomirecki