胸腺嘧啶结合集合

Question

我在使用spring和thymeleaf绑定集合时遇到了问题。每次发送表单时，对象集合都被设置为null (User.postions)，下面是我的示例：

我的财务主任：

@RequestMapping(value = urlFragment + "/add", method = RequestMethod.GET)
public String addPosition(Model model) {

    HashSet<Position> positions = new HashSet<Position>(positionRepository.findByEnabledTrueOrderByNameAsc());

    User employee = new User();

    for (Position position : positions) {
        employee.addPosition(position);
    }

    model.addAttribute("employee", employee);

    return "crud/employee/add";
}

@RequestMapping(value = urlFragment + "/add", method = RequestMethod.POST)
public String processNewEmployee(Model model, @Valid @ModelAttribute("employee") User employee, BindingResult result) {
    String templatePath = "crud/employee/add";

    if (!result.hasErrors()) {
        userRepository.save(employee);
        model.addAttribute("success", true);
    }

    return templatePath;
}

我的雇员表格：

<form action="#" th:action="@{/panel/employee/add}" th:object="${employee}" method="post">

    <div class="row">
        <div class="col-md-6">
            <label th:text="#{first_name}">First name</label>
            <input class="form-control" type="text" th:field="*{userProfile.firstName}"/>
        </div>
    </div>

    <div class="row">
        <div class="col-md-6">
            <label th:text="#{last_name}">Last name</label>
            <input class="form-control" type="text" th:field="*{userProfile.lastName}"/>
        </div>
    </div>

    <div class="row">
        <div class="col-md-6">
            <label th:text="#{email}">Email</label>
            <input class="form-control" type="text" th:field="*{email}"/>
        </div>
    </div>

    <div class="row">
        <div class="col-md-6">
            <label th:text="#{position}">Position</label>
            <select th:field="*{positions}" class="form-control">
                <option th:each="position : *{positions}"
                        th:value="${position.id}"
                        th:text="${position.name}">Wireframe
                </option>
            </select>
        </div>
    </div>


    <div class="row">
        <div class="col-md-5">
            <div class="checkbox">
                <button type="submit" class="btn btn-success" th:text="#{add_employee}">
                    Add employee
                </button>
            </div>
        </div>
    </div>
</form>

用户实体：

@Entity
@Table(name="`user`")
public class User extends BaseModel {

    @Column(unique = true, nullable = false, length = 45)
    private String email;

    @Column(nullable = false, length = 60)
    private String password;

    @Column
    private String name;

    @Column
    private boolean enabled;

    @ManyToMany(fetch = FetchType.EAGER, cascade = CascadeType.ALL)
    @JoinTable(name = "user_role",
            joinColumns = {@JoinColumn(name = "user_id", nullable = false)},
            inverseJoinColumns = {@JoinColumn(name = "role_id", nullable = false)}
    )
    private Collection<Role> roles = new HashSet<Role>();

    @ManyToMany(fetch = FetchType.LAZY, cascade = CascadeType.ALL)
    @JoinTable(name = "user_position",
            joinColumns = {@JoinColumn(name = "user_id", nullable = false)},
            inverseJoinColumns = {@JoinColumn(name = "position_id", nullable = false)}
    )
    private Collection<Position> positions = new HashSet<Position>();

    public User() {
    }

    public User(String email, String password, boolean enabled) {
        this.email = email;
        this.password = password;
        this.enabled = enabled;
    }

    public User(String email, String password, boolean enabled, Set<Role> roles) {
        this.email = email;
        this.password = password;
        this.enabled = enabled;
        this.roles = roles;
    }

    public String getEmail() {
        return email;
    }

    public void setEmail(String email) {
        this.email = email;
    }

    public boolean isEnabled() {
        return enabled;
    }

    public void setEnabled(boolean enabled) {
        this.enabled = enabled;
    }

    public String getName() {
        return name;
    }

    public void setName(String name) {
        this.name = name;
    }

    public String getPassword() {
        return password;
    }

    public void setPassword(String password) {
        this.password = password;
    }

    public Collection<Position> getPositions() {
        return positions;
    }

    private void setPositions(Collection<Position> positions) {
        this.positions = positions;
    }

    public boolean addPosition(Position position) {
        return positions.add(position);
    }

    public boolean removePosition(Position position) {
        return positions.remove(position);
    }

    public Collection<Role> getRoles() {
        return roles;
    }

    private void setRoles(Collection<Role> roles) {
        this.roles = roles;
    }

    public boolean addRole(Role role) {
        return roles.add(role);
    }

    public boolean removeRole(Role role) {
        return roles.remove(role);
    }

    @Override
    public String toString() {
        return User.class + " - id: " + getId().toString() + ", email: " + getEmail();
    }
}

我在某个地方读到了必须创建equals()和hashCode()的内容，所以我在我的位置实体中这样做了。

public boolean equals(Position position) {
    return this.getId() == position.getId();
}

public int hashCode(){
    return this.getId().hashCode() ;
}

以下是用post方法发送的数据：

​

以下是我的研究结果：

​

我的春季版本:4.1.6.dialect- spring 4版本:2.1.4.dialect-布局-方言版本: 1.2.8

当然，我希望位置是HashCode，有一个id = 2的物体位置元素，你能帮我吗？我做错什么了？

Answer 1

谢谢各位回答我的问题。你帮了我很多。不幸的是，我不得不在一件事上不同意你的观点。你给我举了一个例子：

newPosition.setId(position.getId());

在安德鲁 github存储库中也有相同的例子。我认为使用setId()方法是错误的做法。因此，我将提出我的解决方案，我将等待一些意见，然后我将它标记为一个答案。

WebMvcConfig类

@Configuration
@EnableWebMvc
@ComponentScan(basePackages = "com.smartintranet")
public class WebMvcConfig extends WebMvcConfigurerAdapter {

    @PersistenceContext
    private EntityManager entityManager;

    // (....rest of the methods.......)

    @Override
    public void addFormatters(FormatterRegistry formatterRegistry) {
        formatterRegistry.addFormatter(new PositionFormatter(entityManager));
    }
}

PositionFormatter类

public class PositionFormatter implements Formatter<Position> {

    private EntityManager entityManager;

    public PositionFormatter(EntityManager entityManager) {
        this.entityManager = entityManager;
    }

    public String print(Position position, Locale locale) {
        if(position.getId() == null){
            return "";
        }

        return position.getId().toString();
    }

    public Position parse(String id, Locale locale) throws ParseException {
        return entityManager.getReference(Position.class, Long.parseLong(id));
    }
}

employeeForm.html

                <div class="col-md-6">
                    <label th:text="#{position}">Position</label>
                    <select th:field="*{position}" class="form-control">
                        <option th:each="position : ${allPositions}"
                                th:value="${position.id}"
                                th:text="${position.name}">Wireframe
                        </option>
                    </select>
                </div>

和最后一个，EmployeeController类

@Controller
public class EmployeeController extends AbstractCrudController {    
    // (...rest of dependency and methods....)

    @Transactional
    @RequestMapping(value = urlFragment + "/create", method = RequestMethod.GET)
    public String createNewEmployee(Model model) {
        prepareEmployeeForm(model);
        return "crud/employee/create";
    }

    @Transactional
    @RequestMapping(value = urlFragment + "/create", method = RequestMethod.POST)
    public String processNewEmployee(Model model, @ModelAttribute("employee") Employee employee, BindingResult result) {
        if (!result.hasErrors()) {
            // Look here it is important line!
            entityManager.merge(employee.getUser());
        }

        prepareEmployeeForm(model);

        return "crud/employee/create";
    }
}

这是我的解决办法。这里有什么不好的？我想这句话是：

entityManager.merge(employee.getUser());

我不能在这里用：

userRepository.save(employee.getUser());

因为位置实体是分离的，当我使用保存方法时，它在这种情况下运行em.persist()，所以我手动运行em.merge()。我知道这段代码并不完美，但我认为这个解决方案比使用setId()更好。我将感谢建设性的批评。

再一次感谢安德鲁和布莱泽没有你的帮助，我不会这么做的。我把你的答案标为有用的。

Answer 2

这是因为您使用${position.id}作为您的选项值。这意味着spring无法计算值中使用的id与实际位置对象之间的关系。试着用${position}来表示您的价值，它应该可以工作：

                    <select th:field="*{positions}" class="form-control">
                        <option th:each="position : *{positions}"
                                th:value="${position}"
                                th:text="${position.name}">Wireframe
                        </option>
                    </select>

(确保您已经实现了hashCode并在您的位置类上实现了等号)

如果这仍然不起作用，您可能必须实现一个格式化程序的位置，以使转换显式。参见下面的示例胸腺瘤样例.选择倍数。

Answer 3

通过向MVC的配置添加格式化程序类和添加格式化程序，我也解决了类似的问题：

@Override
protected void addFormatters(FormatterRegistry registry){
    registry.addFormatter(new PositionFormater());
    ...
}

位置类格式化程序应该如下所示：

PositionFormatter：

public class PositionFormatter implements Formatter<Position>{

/** String representing null. */
private static final String NULL_REPRESENTATION = "null";

@Resource
private PositionRepository positionRepository;

public PositionFormatter() {
    super();
}

@Override
public String print(Position position, Locale locale) {
    if(position.equals(NULL_REPRESENTATION)){
        return null;
    }
    try {
        Position newPosition = new Position();
        newPosition.setId(position.getId());
        return newPosition.getId().toString();
    } catch (NumberFormatException e) {
        throw new RuntimeException("Failed to convert `" + position + "` to a valid id");
    }

}

@Override
public Position parse(String text, Locale locale) throws ParseException {
    if (text.equals(NULL_REPRESENTATION)) {
        return null;
    }
    try {
        Long id = Long.parseLong(text);
        Position position = new Position();
        position.setId(id);
        return position;
    } catch (NumberFormatException e) {
        throw new RuntimeException("Failed to convert `" + text + "` to valid Position");
    }
  }
}

就我而言，这两个人解决了所有问题。我有几个格式化程序，我所做的就是把它添加到配置文件中(在我的例子中是WebMVCConfig)。

查看我解决这个问题的原稿。