由于SPRING转换失败导致400错误

Question

我正在尝试使用SPRING Converter接口将id转换为对象但是当我发布表单时我遇到了400错误的请求错误我有一个看起来像这样的代码 这是转换器

@Component
public class LocationConverter implements Converter<Object, Location> {

@Autowired
LocationService locationService;

@Override
public Location convert(Object element) {

    Integer id = Integer.parseInt((String)element);
    Location l = locationService.getById(id);

    return l;
}
}

我正在使用基于注释的配置，所以我正在注册它

@Override
 public void addFormatters(FormatterRegistry registry){
     registry.addConverter(new CategoryConverter());
     registry.addConverter(new LocationConverter());
     registry.addConverter(new SupplierConverter());
 }

控制器

@RequestMapping(value="/create", method=RequestMethod.POST)
public String createOrUpdateArticle(@ModelAttribute Article article,String action,MultipartFile file) 
        throws IOException{

    if(action.equals("create")){
        if( !file.isEmpty() ) { 
            article.setImage(file.getBytes());
        }
        articleService.create(article);
    }

    if(action.equals("update")){
        articleService.update(article);
    }

    return "redirect:/article/";
}

并在视图中

<f:form modelAttribute="article" enctype="multipart/form-data"  method="post" 
                                        action="${pageContext.request.contextPath}/article/create">                                        
                                    <input type="hidden" name="action" value="${action}"/>  
                                    <f:input type="hidden" path="id"/>
                                    <div class="col-md-6 form-group">
                                        <label>CodeBarre</label>
                                        <f:input path="code" class="form-control"/>
                                    </div>
                                    <div class="col-md-6 form-group">
                                        <label>Description</label>
                                        <f:input path="description" class="form-control"/>
                                    </div>
                                    <div class="col-md-6 form-group">
                                        <label>Prix Grossier</label>
                                        <f:input path="price1" class="form-control"/>
                                    </div>
                                    <div class="col-md-6 form-group">
                                        <label>Prix Semi Grossier</label>
                                        <f:input path="price2" class="form-control"/>
                                    </div>
                                    <div class="col-md-6">
                                        <div class="form-group">
                                            <label>Categorie</label>
                                            <f:select cssClass="form-control" path="category" items="${categories}" 
                                                      itemValue="id" itemLabel="name"/>
                                        </div>
                                    </div>
                                    <div class="col-md-6">
                                        <div class="form-group">
                                            <label>Location</label>
                                            <f:select cssClass="form-control" path="location" items="${locations}" 
                                                      itemValue="id" itemLabel="name"/>
                                        </div>
                                    </div>
                                    <div class="col-md-6">
                                        <div class="form-group">
                                            <label>Fournisseur</label>
                                            <f:select cssClass="form-control" path="suppliers" items="${suppliers}" 
                                                      multiple="true" itemValue="id" itemLabel="firstName"/>
                                        </div>
                                    </div>
                                    <div class="col-md-6">
                                        <div class="form-group">
                                            <label>Photo</label>
                                            <input type="file" name="file" class="form-control" />
                                        </div>
                                    </div>
                                    <button type="submit" class="btn btn-sm-default pull-right">Ajouter</button>
                                </f:form>

错误消息

Field error in object 'article' on field 'category': rejected value [3]; codes [typeMismatch.article.category,typeMismatch.category,typeMismatch.ma.stock.app.entities.Category,typeMismatch]; arguments [org.springframework.context.support.DefaultMessageSourceResolvable: codes [article.category,category]; arguments []; default message [category]]; default message [Failed to convert property value of type 'java.lang.String' to required type 'ma.stock.app.entities.Category' for property 'category'; nested exception is org.springframework.core.convert.ConversionFailedException: Failed to convert from type java.lang.String to type @javax.persistence.ManyToOne ma.stock.app.entities.Category for value '3'; nested exception is java.lang.NullPointerException]

字段'location'上对象'article'中的字段错误：被拒绝的值[2];代码[typeMismatch.article.location，typeMismatch.location，typeMismatch.ma.stock.app.entities.Location，typeMismatch]; arguments [org.springframework.context.support.DefaultMessageSourceResolvable：codes [article.location，location];参数[];默认消息[location]];默认消息[无法将类型'java.lang.String'的属性值转换为属性'location'所需的类型'ma.stock.app.entities.Location';嵌套异常是org.springframework.core.convert.ConversionFailedException：无法从类型java.lang.String转换为类型@javax.persistence.OneToOne ma.stock.app.entities.Location为值'2';嵌套异常是java.lang.NullPointerException] 字段“供应商”中对象“文章”中的字段错误：被拒绝的值[4];代码[typeMismatch.article.suppliers，typeMismatch.suppliers，typeMismatch.java.util.Set，typeMismatch]; arguments [org.springframework.context.support.DefaultMessageSourceResolvable：codes [article.suppliers，suppliers];参数[];默认消息[供应商]];默认消息[无法将类型'java.lang.String'的属性值转换为属性'供应商'所需的类型'java.util.Set';嵌套异常是org.springframework.core.convert.ConversionFailedException：无法从类型java.lang.String转换为类型@javax.persistence.ManyToMany @ javax.persistence.JoinTable ma.stock.app.entities.Supplier for value'4 “;嵌套异常是java.lang.NullPointerException]

我不知道我在这里缺少什么， 提前谢谢。