Send object from th:each loop to controller - spring

Question

I have form and corresponding controller to which list of objects is passed.
entity classes:
#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;
controller:
#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:/"
}
form:
<form method="post" th:action="#{create/new}">
<select class="form-control" name="entity2list">
<option th:each="ent2:${entity2list}
th:value="${ent2.name} th:text="${ent2.name}>
</select>
<button type="submit"></button>
</form>
I suppose that thymeleaf th:each loop variable in form can't be th:object=${ent2} (cause if i do this way, select form return null).
Whereas th:value="${ent2.name} return string value. So i had to send #RequestParam(th:value) to "save" method. But in this case i had to do additional request to database, to get Entity2 object and set it to Entity1.
How can i get entity object in some way like:
<form method="post" th:action="#{create/new}">
<select class="form-control">
<option th:each="ent2:${entity2list}
th:object="${ent2} th:text="${ent2.name}>
</select>
<button type="submit"></button>
</form>
and send (#ModelAttribute("ent2")Entity2 ent2 instead of #RequestParam) to the "save" method to avoid redundant request to database?

Answer 1

i have solved the issue th:field="*{entity2Field} works like setter
https://www.thymeleaf.org/doc/tutorials/3.0/thymeleafspring.html#creating-a-form
<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>