[英]Spring MVC with Hibernate Data Saving Error
I have two tables: Company and Automotive. 我有两个表:Company和Automotive。 A company can have many automotives. 一个公司可以有很多汽车。 I am unable to persist an Automotive properly. 我无法正确坚持汽车。 Company is selected in View page from a drop down. 在“查看”页面的下拉菜单中选择了“公司”。
My Controller 我的控制器
@RequestMapping("/")
public String view(ModelMap model) {
Map<String, String> companyList = new HashMap<String, String>();
List<Company> companies = companyService.listAllCompanies();
for (Company company : companies) {
companyList.put(String.valueOf(company.getId()), company.getName());
}
model.addAttribute("companies", companyList);
model.addAttribute("automotive", new Automotive());
return "automotive/index";
}
@RequestMapping("manage")
public String manage(@ModelAttribute Automotive automotive,
BindingResult result, ModelMap model) {
model.addAttribute("automotive", automotive);
Map<String, String> companyList = new HashMap<String, String>();
List<Company> companies = new ArrayList<Company>();
for (Company company : companies) {
companyList.put(String.valueOf(company.getId()), company.getName());
}
model.addAttribute("companies", companyList);
automotiveService.addAutomotive(automotive);
return "automotive/index";
}
My View 我的观点
<form:form action="/Automotive/manage" modelAttribute="automotive">
Name : <form:input path="name" />
Description : <form:input path="description" />
Type : <form:input path="type" />
Company : <form:select path="company" items="${companies}" />
<input type="submit" />
</form:form>
Q1> Logically as expected Company id would not be saved since here in view its an id but actually while saving it should be an object of type company. Q1>从逻辑上讲,不会保存公司ID,因为在这里查看其ID,但实际上在保存时它应该是公司类型的对象。 How should I solve this. 我该如何解决。 Do I need to use a DTO or is there any direct method? 我需要使用DTO还是有直接方法?
Q2> Can't i pass Company list directly to view instead of creating a new Map in controller? Q2>我不能直接通过公司列表进行查看,而不是在控制器中创建新地图吗?
You can use id of company as a key and then use converter which will automatically convert data from form into domain object. 您可以将公司ID用作密钥,然后使用转换器将数据自动从表单转换为域对象。 Just like in this code: 就像下面的代码:
public class CompanyIdToInstanceConverter implements Converter<String, Company> {
@Inject
private CompanyService _companyService;
@Override
public Company convert(final String companyIdStr) {
return _companyService.find(Long.valueOf(companyIdStr));
}
}
And in JSP: 在JSP中:
<form:select path="company" items="${companies}" itemLabel="name" itemValue="id"/>
You may need to read more about type conversion if you haven't touched this yet. 如果您尚未接触类型转换,则可能需要阅读更多信息。 It is perfectly described in Spring doc (I you couldn't find: http://static.springsource.org/spring/docs/3.0.x/reference/validation.html paragraph 5.5). Spring文档中对此进行了完美的描述(我找不到: http : //static.springsource.org/spring/docs/3.0.x/reference/validation.html第5.5段)。
I hope it would help you. 希望对您有帮助。
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