[我在尝试使用Freemarker Spring Boot删除元素时遇到异常505

Question

错误是：发生意外错误（类型=内部服务器错误，状态= 500）。指定的ID不能为null！嵌套异常是java.lang.IllegalArgumentException：给定的id不能为null！org.springframework.dao.InvalidDataAccessApiUsageException

那是我的控制器

    @GetMapping("delete/{topic}")
public String delete(Long id) {
    topicRepos.deleteById(id);
    return "redirect:/topic-list";
}

存储库

public interface TopicRepos extends JpaRepository<Topic,Long> {

public Topic deleteById(int id);}

实体

@Id
@GeneratedValue(strategy = GenerationType.IDENTITY)
privatre Long id;
private String topicName;
private String topicMessage;
private String topicDescribe;

@OneToMany(cascade = CascadeType.ALL, fetch = FetchType.LAZY)
@JoinColumn(name="id_topic")
private List<Message> messages;

public Topic() {}

public Topic(String topicName, String topicMessage) {
    this.topicName = topicName;
    this.topicMessage = topicMessage;
}

public Topic(String topicName, String topicMessage, String topicDescribe) {
    this.topicName = topicName;
    this.topicMessage = topicMessage;
    this.topicDescribe = topicDescribe;
}

public List<Message> getMessages() {
    return messages;
}

public void setMessages(List<Message> messages) {
    this.messages = messages;
}

public Long getId() {
    return id;
}

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

public String getTopicName() {
    return topicName;
}

public void setTopicName(String topicName) {
    this.topicName = topicName;
}

public String getTopicMessage() {
    return topicMessage;
}

public void setTopicMessage(String topicMessage) {
    this.topicMessage = topicMessage;
}

public String getTopicDescribe() {
    return topicDescribe;
}

public void setTopicDescribe(String topicDescribe) {
    this.topicDescribe = topicDescribe;
}

>

html和自由标记代码

<#list topics.content as tempTopic>
<tr>
<td>${tempTopic.topicName}</td>
<td><a href="/topic/${tempTopic.id}" class="btn btn-info btn-sm mb-3">Follow</a>
<a href="/topic/delete/${tempTopic.id}"
				class="btn btn-danger btn-sm"
				 onclick="if (!(confirm('Are you sure you want to delete this topic?'))) return false">
					Delete</a></td>
</td>
</tr>
</#list>

Answer 1

您的主题ID未映射到delete方法的参数。

使用@PathVariable将路径变量映射到方法参数中。

@GetMapping("delete/{topic}")
public String delete(@PathVariable("topic") Long id) {