java - 我无法通过控制器传输许多对象(((
问题描述
当我尝试通过控制器传输大量数据时,出现错误:
出现意外错误(类型=错误请求,状态=400)。无法将类型“java.lang.String”的值转换为所需类型“com.psu.projectmethod.domain.wrappers.UserSet”;嵌套异常是 org.springframework.core.convert.ConversionFailedException:无法从类型 [java.lang.String] 转换为类型 [@org.springframework.web.bind.annotation.ModelAttribute com.psu.projectmethod.domain.wrappers。 UserSet] 为值 'com.psu.projectmethod.domain.User@23'; 嵌套异常是 java.lang.IllegalArgumentException:无法实例化集合类型:com.psu.projectmethod.domain.wrappers.UserSet org.springframework.beans.TypeMismatchException:无法将“java.lang.String”类型的值转换为所需类型'com.psu.projectmethod.domain.wrappers.UserSet'; 嵌套异常是 org.springframework。core.convert.ConversionFailedException:无法从类型 [java.lang.String] 转换为值 'com. psu.projectmethod.domain.User@23'; 嵌套异常是 java.lang.IllegalArgumentException:无法实例化集合类型:com.psu.projectmethod.domain.wrappers.UserSet
我根据 stackoverflow 中的示例和这篇文章https://www.viralpatel.net/spring-mvc-multi-row-submit-java-list/做了所有事情。请帮我解决这个问题((
我的控制器方法:
@PreAuthorize("hasAuthority('_2_TEACHER')")
@GetMapping("/project/{projectId}/party/create")
public String viewTeacherCreateProjectParty(
@PathVariable("projectId") Project project,
Party party,
Model model) {
Set<User> users = userService.userList(Sort.by("username"));
UserSet userSet = new UserSet(users);
model.addAttribute("project", project);
model.addAttribute("party", party);
model.addAttribute("users", userSet.getUsers());
return "teacherProjectPartyCreate";
}
@PreAuthorize("hasAuthority('_2_TEACHER')")
@PostMapping("/project/{projectId}/party/create")
public String processCreateProjectParty(
@PathVariable("projectId") Project project,
@Valid Party party,
@ModelAttribute("users") UserSet users,
Model model) {
model.addAttribute("project", project);
model.addAttribute("party", party);
Long projectId = projectService.createProjectParty(project, party, users);
return "redirect:/projects/project/" + projectId;
}
自由标记形式:
<form action="/projects/project/${project.projectId}/party/create" method="post"
style="color: #757575;">
<!-- CSRF Token -->
<input type="hidden" name="_csrf" value="${_csrf.token}"/>
<div class="md-form">
<input type="text" id="partyName" name="partyName" value="${party.partyName!''}"
class="form-control ${(partyNameError??)?string('is-invalid', '')}" required>
<label for="partyName">Group name</label>
<#if partyNameError??>
<div class="invalid-feedback">
${partyNameError}
</div>
</#if>
</div>
<select name="users" class="selectpicker"
data-header="Select users"
data-live-search="true"
data-selected-text-format="count"
data-size="auto"
data-style="btn-unique"
data-width="auto"
multiple
title="Select users"
>
<#list users as user>
<option value="${user}">${user.fullname}</option>
</#list>
</select>
<div class="modal-footer d-flex justify-content-center">
<button type="button" onClick='location.href="/projects/project/${project.projectId}"'
class="btn btn-outline-info waves-effect">
Отмена
</button>
<button type="submit" class="btn btn-primary waves-effect">
Save
</button>
</div>
</form>
我的实体创建方法
public Long createProjectParty(Project project, Party party, Set<User> users) {
project.addParty(party);
party.addUsers(party, users);
projectRepo.save(project);
return project.getProjectId();
}
添加双向关联的辅助方法:
public void addParty(Party party) {
party.setPartyProject(this);
this.projectParties.add(party);
}
public void addUsers(Party party, Set<User> users) {
party.setPartyUsers(users);
this.partyUsers.addAll(users);
}
多对多关联映射:
@ManyToMany(fetch = FetchType.LAZY,
cascade = {CascadeType.PERSIST, CascadeType.DETACH, CascadeType.REFRESH, CascadeType.REMOVE}
)
@JoinTable(name = "party_users",
joinColumns = {@JoinColumn(name = "fk_party_id")},
inverseJoinColumns = {@JoinColumn(name = "fk_user_id")})
private Set<User> partyUsers = new HashSet<>();
public class UserSet implements Set<User> {
private Set<User> users;
public UserSet(Set<User> users) {
this.users = users;
}
public Set<User> getUsers() {
return users;
}
public void setUsers(Set<User> users) {
this.users = users;
}
... // getters, setters and Set metods
解决方案
在分析了您的日志后,我发现您的请求有问题。
仔细阅读此日志条目:
Failed to convert value of type 'java.lang.String' to required type 'com.psu.projectmethod.domain.wrappers.UserSet'
看来您正试图发送String
到预期的地方UserSet
。如果需要这种行为,请考虑使用转换器。检查文章
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