这些是 bean :
@Entity
@Table(name = "bands")
public class Band implements Serializable {
@Id
@GeneratedValue(strategy = GenerationType.IDENTITY)
public Integer band_id;
@Column(name = "name")
@NotEmpty
public String name;
@Column(name = "formed")
@NotNull
public Integer formed;
@ManyToOne
@JoinColumn(name = "genre_id")
public Genre genre;
public Integer getBandId() {
return band_id;
}
public void setBandId(Integer band_id) {
this.band_id = band_id;
}
public String getName() {
return this.name;
}
public void setName(String name) {
this.name = name;
}
public Integer getFormed() {
return this.formed;
}
public void setFormed(Integer formed) {
this.formed = formed;
}
public Genre getGenre() {
return genre;
}
public void setGenre(Genre genre) {
this.genre = genre;
}
@XmlElement
public Genre getGenres() {
Genre genre = getGenre();
return genre;
}
}
@Entity
@Table(name = "genres")
@Access(AccessType.FIELD)
public class Genre implements Serializable {
@Id
@GeneratedValue(strategy = GenerationType.IDENTITY)
public Integer genre_id;
@Column(name = "name")
@NotEmpty
public String name;
@OneToMany(cascade = CascadeType.ALL, mappedBy = "genre")
public Set<Band> bands;
public Integer getGenreId() {
return genre_id;
}
public void setGenreId(Integer genre_id) {
this.genre_id = genre_id;
}
public String getName() {
return this.name;
}
public void setName(String name) {
this.name = name;
}
public Set<Band> getBands() {
return this.bands;
}
public void setBands(Set<Band> bands) {
this.bands = bands;
}
}
这是 Controller 中初始化页面然后调用保存操作的部分:
@RequestMapping(value = "/bands/{band_id}/edit", method = RequestMethod.GET)
public String initUpdateBandForm(@PathVariable("band_id") int band_id, ModelMap model) {
model.addAttribute("genres", this.bandRepository.findAllGenres());
Band band = this.bandRepository.findById(band_id);
model.addAttribute("band", band);
return "bands/updateBandForm";
}
@RequestMapping(value = "bands/{band_id}/edit", method = RequestMethod.POST)
public String processUpdateBandForm(@Valid @ModelAttribute("band") Band band, BindingResult result) {
if (result.hasErrors()) {
return "bands/updateBandForm";
} else {
this.bandRepository.save(band);
return "redirect:/bands/{band_id}";
}
}
这是存储库保存操作:
void save(Band band);
这是 updateBandForm:
<form th:object="${band}" method="post">
<label>Name</label>
<input type="text" th:field="*{name}" />
<label>Formed</label>
<input type="text" th:field="*{formed}" />
<label>Genre</label>
<select th:field="*{genre}">
<option th:each="genre: ${genres}" th:value="${{genre}}" th:text="${genre.name}" />
</select>
<br>
<button type="submit">Update Band</button>
</form>
我还使用格式化程序:
@Service
public class GenreFormatter implements Formatter<Genre> {
@Autowired
GenreRepository genreRepository;
@Override
public String print(Genre genre, Locale locale) {
return (genre != null ? genre.getGenreId().toString() : "");
}
@Override
public Genre parse(String text, Locale locale) throws ParseException {
Integer id = Integer.valueOf(text);
return this.genreRepository.findById(id);
}
}
@Configuration
@EnableWebMvc
@ComponentScan(value = {"org.springframework.samples.discography.system"})
public class WebConfig extends WebMvcConfigurerAdapter {
@Autowired
private GenreFormatter genreFormatter;
@Override
public void addFormatters(FormatterRegistry registry) {
registry.addFormatter(genreFormatter);
}
}
Controller 方法创建一个新行而不是更新现有行...任何人都可以帮忙吗? 我错过了什么吗?
最佳答案
您的 HTML 表单没有 ID 信息。
@ModelAttribute
将创建一个 Band
对象,其中包含在 HTML 表单发送的请求参数中找到的数据。
由于您的表单只有 name
、formed
和 genre
,因此 processUpdateBandForm 中的
有一个未初始化的 Band
对象band_id
字段,导致在保存
时创建一个新的Band
。
在表单中添加 ID 信息来解决此问题。
<input type="hidden" th:field="*{bandId}" />
关于java - Spring boot 创建新行而不是更新,我们在Stack Overflow上找到一个类似的问题: https://stackoverflow.com/questions/44330265/