JSF 嵌套对象在提交时设置为空

Question

我面临这个 SO 线程 Why does JSF null out a nested class successfully instantiated in the backing bean? 中描述的类似问题 我有一个简单的表单（JSF-2.2）来创建一个具有多个嵌套对象及其各自属性的对象。实例化成功发生，我可以看到所有对象及其子对象不为空，但由于某种原因，当我提交表单时，整个对象树再次设置为空。在下面的示例中，值模板将导致

javax.el.PropertyNotFoundException: 目标无法到达，'null' 返回 null。

因为出于某种原因，ArticleListConfiguration 在提交之前被设置为 null。

<ui:composition template="../template/template.xhtml">
<ui:define name="content">
    <h:form id="createArticleListForm">
        <p:panel styleClass="content-panel">
            <h:panelGrid
                    columns="2"
                    styleClass="borderless-grid"
                    columnClasses="create-article-list-panel, create-article-list-panel">
                <p:panel
                        id="listValuesPanel">
                    <p:inputText
                            id="articleListName"
                            value="#{createArticleListController.articleList.name}"/>
                    <p:inputText
                            id="articleListSize"
                            maxlength="3"
                            value="#{createArticleListController.articleListSize}">
                    </p:inputText>
                    <p:selectBooleanCheckbox
                            id="saveArticleListConfigurationAsTemplate"
                            value="#{createArticleListController.articleList.articleListConfiguration.template}"/>
                    <h:panelGrid
                            columns="1">
                        <p:fileUpload
                                id="upload"
                                widgetVar="fileUploadWidget"
                                fileUploadListener="#{createArticleListController.uploadImages}"
                                multiple="true"
                                onstart="submitSelection()"
                                oncomplete="handleMultiFileUploadRequest(PF('fileUploadWidget'));"
                                allowTypes="/(\.|\/)(jpg|png)$/"
                                styleClass="ui-widget"/>
                        <p:remoteCommand
                                name="submitSelection"
                                process="@this"/>
                    </h:panelGrid>
                </p:panel>
            </h:panelGrid>
            <br/>
            <p:commandButton
                    id="createArticleListButton"
                    process="@this @form"
                    value="#{contentController.getContent('createArticleList')}"
                    actionListener="#{createArticleListController.onCreate()}"/>
        </p:panel>
    </h:form>
</ui:define>

这是支持 bean

@ManagedBean
@ViewScoped
public class CreateArticleListController extends AbstractController {

@Inject
private ArticleListService articleListService;

private ArticleList articleList;
private Integer articleListSize;
private List<Pair<String, InputStream>> files;


@PostConstruct
public void init() {
    //The constructor of ArticleList creates and attaches instances of all necessary nested objects
    articleList = new ArticleList();
    files = new ArrayList<>();
}

public void onCreate() throws IOException {
    articleListService.create(articleList, files);
    navigateTo("articleListOverview");
}

public void uploadImages(FileUploadEvent event) {
    try {
        files.add(Pair.of(event.getFile().getFileName(), event.getFile().getInputstream()));
    } catch (IOException e) {
        LOGGER.log(Level.ERROR, "Error uploading files");
        JsfMessageUtils.sendErrorMessageToUser("Error uploading files");
    }
}

public ArticleList getArticleList() {
    return articleList;
}

public void setArticleList(ArticleList articleList) {
    this.articleList = articleList;
}

public Integer getArticleListSize() {
    return articleListSize;
}

}

Answer 1

缺少二传手

private Integer articleListSize;

而p:inputText 找不到它。

添加

public void setArticleListSize(Integer articleListSize) {
    this.articleListSize = articleListSize;
}

到CreateArticleListController。

还要确保 ArticleList 类及其子类已定义所有引用的 getter 和 setter。

更新：

我创建的控制器工作正常与您的原始 xhtml 页面

//...
import javax.faces.bean.ViewScoped;
//...

@ManagedBean(name = "createArticleListController")
@ViewScoped
public class CreateArticleListController implements Serializable {

    ArticleList articleList;
    private Integer articleListSize;

    @PostConstruct
    public void init() {
        System.out.println("On init controller");
        // initiliazing data
        articleList = new ArticleList();
        articleList.setName("List 1");
        //if you omit following lines, you will get the same exception posted in your question
        ArticleListConfiguration ac = new ArticleListConfiguration();
        ac.setTemplate(false);
        articleList.setArticleListConfiguration(ac);
    }

    public ArticleList getArticleList() {
        return articleList;
    }

    public void setArticleList(ArticleList articleList) {
        this.articleList = articleList;
    }

    public Integer getArticleListSize() {
        return articleListSize;
    }

    public void setArticleListSize(Integer articleListSize) {
        this.articleListSize = articleListSize;
    }

    public void onCreate() throws IOException {
        System.out.printf("On create -> Article name: %s, size: %s, template: %s\r\n", articleList.getName(), articleListSize, articleList.getArticleListConfiguration().isTemplate());
    }

    public void uploadImages(FileUploadEvent event) {
        System.out.println("On upload image " + event.getFile().getFileName());
    }
}

因此，ArticleList 或其他对象的初始化过程肯定缺少某些东西。使用您的页面运行我的示例控制器并检查它是否工作正常并将您的调试范围缩小到问题中未发布的控制器部分。