我正在學習 Spring Boot。我想參考 MySQL 資料并在 Thymeleaf 中顯示 MySQL 資料。但是，我收到以下錯誤：
java.sql.SQLSyntaxErrorException：“欄位串列”中的“employee0_.department_department_id”列未知。
另外，我想設定為從 Employee 類參考 Department 類。(@ManyToOne) 但我不確定當前的物體類和 MySQL 設定是否正確。
員工控制器
package com.example.demo.controller;
@RequiredArgsConstructor
@Controller
public class EmployeeController {
private final EmployeeRepository emRepository;
private final DepartmentRepository deRepository;
@GetMapping("/")
public String showList(Model model) {
model.addAttribute("employeeList", emRepository.findAll());
return "index";
}
@GetMapping("/add")
public String addEmployee(@ModelAttribute Employee employee, Model model) {
model.addAttribute("departmentList", deRepository.findAll());
return "form";
}
@PostMapping("/save")
public String process(@Validated @ModelAttribute Employee employee, BindingResult result) {
if (result.hasErrors()) {
return "form";
}
emRepository.save(employee);
return "index";
}
@GetMapping("/edit/{id}")
public String editEmployee(@PathVariable Long id, Model model) {
model.addAttribute("employee", emRepository.findById(id));
return "form";
}
@GetMapping("/delete/{id}")
public String deleteEmployee(@PathVariable Long id) {
emRepository.deleteById(id);
return "redirect:/";
}
}
部門
package com.example.demo.model;
@NoArgsConstructor
@Getter
@Setter
@Entity
public class Department {
@Id
@GeneratedValue(strategy = GenerationType.IDENTITY)
@Column(name="department_id")
private Long department_id;
@NotBlank
@Size(max = 40)
@Column(name="department_name")
private String department_name;
public Department(String name) {
this.department_name = name;
}
}
員工
package com.example.demo.model;
@NoArgsConstructor
@AllArgsConstructor
@Getter
@Setter
@Entity
public class Employee {
@Id
@GeneratedValue(strategy = GenerationType.IDENTITY)
private Long id;
@NotBlank
@Size(max = 40)
private String name;
@ManyToOne
private Department department;
}
部門資料庫
package com.example.demo.repository;
import org.springframework.data.jpa.repository.JpaRepository;
import com.example.demo.model.Department;
public interface DepartmentRepository extends JpaRepository<Department, Long> {
}
員工資料庫
package com.example.demo.repository;
import org.springframework.data.jpa.repository.JpaRepository;
import com.example.demo.model.Employee;
public interface EmployeeRepository extends JpaRepository<Employee, Long> {
}
索引.html
<!DOCTYPE html>
<html xmlns:th="http://www.thymeleaf.org">
<head>
<meta charset="UTF-8">
<title>Employee List</title>
</head>
<body>
<h3>List</h3>
<div th:if="${employeeList.size==0}">
<h3>no data</h3>
</div>
<table th:if="${employeeList.size()>0}">
<tr>
<th>id</th>
<th>name</th>
<th>Department</th>
<th></th>
</tr>
<tr th:each="employee:${employeeList}" th:object="${employee}">
<td th:text="${employee.id}"></td>
<td th:text="${employee.name}"></td>
<td th:text="${employee.department_name}"></td>
<td><form th:action="@{'/delete/' ${employee.id}}" method="post">
<button>delete</button>
</form></td>
<td><form th:action="@{'/edit/' ${employee.id}}" method="post">
<button>edit</button>
</form></td>
</tr>
</table>
<h3>
<a th:href="@{/add}">add</a>
</h3>
</body>
</html>
應用程式屬性
spring.datasource.url=jdbc:mysql://localhost:3306/spring_crud
spring.datasource.username=spring_crud
spring.datasource.password=spring_crud
spring.datasource.driver-class-name=com.mysql.cj.jdbc.Driver
#spring.jpa.hibernate.ddl-auto=update
uj5u.com熱心網友回復：
您可能想嘗試@JoinColumn(name = "department_id")在 Employee 類中的部門資料下添加注釋。或者更詳細的，比如
@Entity
public class Employee {
@Id
@GeneratedValue(strategy = GenerationType.IDENTITY)
private Long id;
@NotBlank
@Size(max = 40)
private String name;
@ManyToOne(targetEntity = Department.class)
@JoinColumn(name = "department_id", referencedColumnName = "department_id")
private Department department;
}
另外，我建議不要department_name在您的員工類（也在資料庫中）使用該列。獲取資料后，您可以使用 getter 獲取屬性。例如employee.getDepartment().getDepartment_name()。
轉載請註明出處，本文鏈接：https://www.uj5u.com/qukuanlian/318571.html
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