Question

产品

@Entity
@Table(name = "product")
@DiscriminatorColumn(name = "type", discriminatorType = DiscriminatorType.STRING)
public class Product {
    @Id
    @Column(name = "id")
    @GeneratedValue()
    private Integer id;
@Column(name = "shortDescription")
    private String shortDescription;

书

@Entity
@DiscriminatorValue(value = "Book")
public class Book extends Product {
    @Column(name = "isbn")
    private String isbn;

控制器

@RequestMapping(value="/product/add",
            method = RequestMethod.POST)
    public String addProduct(@ModelAttribute("product")
         Product product, BindingResult result
            ){
         if(null == product.getId()){
             productService.addProduct(product);
         }else{
             productService.updateProduct(product);
         }
                return "redirect:/";
                }

jsp，我正在尝试显示此属性

    <head>
    <title>Products - Acme Web Store</title>
    <script type="text/javascript">
    function deleteProduct(productId){
        if(confirm('Do you want to delete this product ?')){
            var url = 'delete/'+productId;
            window.location.href = url;
        }
    }
    </script>
</head>
<body>    
        <h2>Product Store - Acme Web Store</h2>
        <p style="color: green; font-weight: bold;">
        To add a new product please click <a href="<c:url var="action" value="/product/add"></c:url>"> <img
            src="<c:url value='/images/vcard_add.png' />"
            title="Add a New Product" />
        </a>
    </p>
    <c:url var="action" value="/product/add"></c:url>
    <form:form method="post" action="${action}" commandName="product"
        cssClass="productForm">
        <table>
            <c:if test="${!empty product.title}">
                <tr>
                    <td><form:label path="id" cssClass="productLabel">
                            <spring:message code="label.productId" />
                        </form:label></td>
                    <td><form:input path="id" readonly="true" size="8"
                            disabled="true" /> <form:hidden path="id" /></td>
                </tr>
            </c:if>
            <tr>
                <td><form:label path="title" cssClass="productLabel">
                        <spring:message code="label.productTitle" />
                    </form:label></td>
                <td><form:input path="title" /></td>
            </tr>
            <tr>
                <td><form:label path="shortDescription" cssClass="productLabel">
                        <spring:message code="label.shortDescription" />
                    </form:label></td>
                <td><form:input path="shortDescription" /></td>
            </tr>
                <tr>
                    <td><form:label path="isbn" cssClass="productLabel">
                            <spring:message code="label.isbn" />
                        </form:label></td>
                    <td><form:input path="isbn" /></td>
                </tr>
                <tr>
                    <td><form:label path="format" cssClass="productLabel">
                            <spring:message code="label.format" />
                        </form:label></td>
                    <td><form:input path="format" /></td>
                </tr>
            <tr>
                <td colspan="2"><c:if test="${!empty product.productName}">
                        <input type="submit"
                            value="<spring:message code="label.editproduct"/>" />
                    </c:if> <c:if test="${empty product.productName}">
                        <input type="submit"
                            value="<spring:message code="label.addproduct"/>" />
                    </c:if></td>
            </tr>
            <tr>
                <td><form:label path="type" cssClass="productLabel">
                        <spring:message code="label.type" />
                    </form:label></td>
                <td>
                <form:select path="type">
                        <form:option value="0" label="Select One" />
                        <form:option value="1" label="Book" />
                        <form:option value="2" label="Game" />
                </form:select>
                </td>
            </tr>
        </table>
    </form:form>


    <h3>List of products in Library</h3>
    <c:if test="${!empty productList}">
        <table class="productTable">
            <tr>
                <th width="160">Product Title</th>
                <th width="190">Product Short Description</th>
                <th width="80">Product ISBN</th>
                <th width="80">Product Format</th>
                <th width="60">Action</th>
            </tr>
            <c:forEach items="${productList}" var="product">
                <tr>
                    <td><a href="<c:url value='/edit/${product.id}' />">${product.productName}</a>
                    </td>
                    <td>${product.title}</td>
                    <td>${product.shortDescription}</td>
                    <td>${product.isbn}</td>
                    <td>${product.format}</td>
                    <td><img src="<c:url value='/images/vcard_delete.png' />"
                        title="Delete product"
                        onclick="javascript:deleteproduct(${product.id})" /> <a
                        href="<c:url value='/edit/${product.id}' />"> <img
                            src="<c:url value='/images/vcard_add.png' />"
                            title="Edit product" />
                    </a></td>
                </tr>
            </c:forEach>
        </table>
    </c:if>


</body>
</html>

我收到此错误： invalid property 'isbn' of bean class [com.mycompany.app.model.Product]: Bean property 'isbn' is not readable or has an invalid getter method: Does the return type of the getter match the parameter type of the setter?

我知道我没有做到这一点，必须有一种方法将Product转换为Book以便我可以获得ISBN属性，我们该怎么做？

Answer 1

只需更改

@ModelAttribute("product") Product product

到

@ModelAttribute("product") Book product

当Spring看到类型Product时，它将创建一个Product对象，而不是Book对象。显然，Product没有名为isbn的属性，因此您不能指望它为该属性解析<form:input>。

您可能想澄清您要做的事情。当您期望子类型时，不能使用超类型。

将子类属性映射到Spring MVC中的表单路径

1 个答案: