将对象从：每个循环发送到控制器

Question

我有形式和对应控制器传递的对象列表。

实体类：

    @Entity
    public class Entity1
       @Id
       @Column(name="id")
       @GeneratedValue(strategy = GenerationType.IDENTITY)
       private long id;
    
       @ManyToOne(cascade = CascadeType.PERSIST)
       @JoinColumn(name = "entity2_id")
       private Entity2 entity2Field; 
    
    @Entity
    public class Entity2
    
       @Id
       @Column(name="id")
       @GeneratedValue(strategy = GenerationType.IDENTITY)
       private long id;
    
       @Column(name="name")
       private String name; 

控制器：

    @GetMapping(value="/create")
    puplic String show(Model entity1Model, Model entity2Model){
        
        entity1Model.addAttribute("entity1", new Entity1());
        List<Entity2> list= entity2Repository.findAll();
        entity2Model.addAttribute("entity2list", list);
        return "form"
        }

    @PostMapping(value="/create/new")
    public String save(Entity1 entity1, @RequestParam(name="entity2list) String somevalue{
        Entity2 entity2= entity2Repository.findByName(somevalue);
        entity1.setEntity2Field(entity2)
        entity1Repository.save(entity1)
        return "redirect:/"  
    }

表格：

<form method="post" th:action="@{create/new}">
  <select class="form-control" name="entity2list">
    <option th:each="ent2:${entity2list} 
      th:value="${ent2.name} th:text="${ent2.name}>
  </select>
  <button type="submit"></button>
</form>

我想百里叶th：表单中的每个循环变量都不能为th：object = $ {ent2}（原因，如果我这样做，请选择form return return null）。 th：value =“ $ {ent2.name}返回字符串值。因此，我必须将@requestParam（th：value）发送到“保存”方法。但是在这种情况下，我必须对数据库提出其他请求，以获取Entity2 并将其设置为Entity1

对象

<form method="post" th:action="@{create/new}">
  <select class="form-control">
    <option th:each="ent2:${entity2list} 
      th:object="${ent2} th:text="${ent2.name}>
  </select>
  <button type="submit"></button>
</form>

。

Answer 1

我解决了问题：field =“*{entity2field}的工作

<form method="post" th:action="@{create/new}" th:object="${entity1}">
      <select class="form-control" th:field="*{entity2Field}>
        <option th:each="ent2:${entity2list} 
          th:value="${ent2} th:text="${ent2.name}></option>
      </select>
      <button type="submit"></button>
</form>