Thymeleaf输出Format对象id时抛出模板解析异常求助

项目引入Spring Security依赖，使用Thymeleaf模板渲染Format实体对象时，title、price等属性均可正常输出，但只要添加th:value="${format.id}"就会抛出模板解析异常，移除该代码后模板可正常加载。

模板代码 #

<label th:each = "format : ${Format}" th:attr="for='label' + ${format.title}" class="btn_order">
    <sup th:text = "${format.title}"/>
    <sup th:text = "${format.price}"/>
    <input class = "radio_settings" name = "price_reload" th:value="${format.id}"   th:attr="id='label' + ${format.title}" type="radio" hidden>
</label>

Format实体类 #

@Entity
@Table(name = "Format")
public class Format {
    
    @Id
    @GeneratedValue(strategy = GenerationType.IDENTITY)
    private Long id;

    @Column(nullable = false, length = 50)
    private String title;

    @Column(nullable = false)
    private Integer lenght;
    
    @Column(nullable = false)
    private Integer width;

    @Column(nullable = false)
    private Integer height;

    @Column(nullable = false)
    private Integer weight;

    @Column(nullable = false)
    private Float price;

    // 原代码未提供id及其他属性的getter/setter方法
}

Controller代码 #

@GetMapping()
public String getWindowOrder(Model model){
    model.addAttribute("title","Create order");
    model.addAttribute("Format", formatService.getByAll());
    return "window_order";
}

Service代码 #

@Service
public class FormatService {

@Autowired
private FormatInterface iFormat;

public List<Format> getByAll (){
        return iFormat.findByAll();
    }
}

Spring Security配置代码 #

@Bean
public SecurityFilterChain securityFilterChain(HttpSecurity http) throws Exception {
    http
        .csrf(AbstractHttpConfigurer::disable)
        .authorizeHttpRequests((requests) -> requests
            .requestMatchers("/", "/registration/**",  "/create/**", "/cart" ,"/image/**", "/css/**", "/js/**","/order","/img/**").permitAll()
            .anyRequest().authenticated()
        )
        .formLogin((form) -> form
            .loginPage("/login")
            .permitAll()
        )
        .logout((logout) -> logout.permitAll());

    return http.build();
}

protected void configure(AuthenticationManagerBuilder auth) throws Exception {
    auth.userDetailsService(userService).passwordEncoder(passwordEncoder);
}

错误日志 #

ERROR 10344 --- [io-8080-exec-10] org.thymeleaf.TemplateEngine             : [THYMELEAF][http-nio-8080-exec-10] Exception processing template "window_cart": An error happened during template parsing (template: "class path resource [templates/window_order.html]")

org.thymeleaf.exceptions.TemplateInputException: An error happened during template parsing (template: "class path resource [templates/window_order.html]")

核心原因 #

Thymeleaf默认通过getter方法访问对象属性，而非直接读取类的字段。你的Format实体类未提供id属性的getter方法，导致模板无法解析该属性。

修复步骤 #

1. 为Format实体添加getter/setter方法
   给id及所有需要在模板中访问的属性添加getter方法，推荐用Lombok的@Data注解自动生成，也可以手动编写：

   @Entity
   @Table(name = "Format")
   @Data // 自动生成所有属性的getter/setter、toString等方法
   public class Format {
       // 原有字段...
   }
   

   手动编写的话，至少添加id的getter：

   public Long getId() {
       return id;
   }
   
   public void setId(Long id) {
       this.id = id;
   }
   

2. 可选：显式类型转换（若仍有问题）
   若添加getter后仍存在Long转String的类型问题，可在模板中显式转换：

   <input th:value="${#strings.toString(format.id)}" ... />
   

   或者直接调用对象的toString方法：

   <input th:value="${format.id.toString()}" ... />
   

验证 #

添加getter方法后重启项目，重新访问页面，模板应能正常渲染format.id的值。

内容的提问来源于stack exchange，提问作者FIDSTONE