jsf - javax.faces.FacesException : Target model Type is no a Collection or Array

Question

提交 JSF 表单时，出现以下异常:

Caused by: javax.faces.FacesException: Target model Type is no a Collection or Array 
    at com.sun.faces.renderkit.html_basic.MenuRenderer.convertSelectManyValuesForModel(MenuRenderer.java:388) [:2.0.3-] 
    at com.sun.faces.renderkit.html_basic.MenuRenderer.convertSelectManyValue(MenuRenderer.java:125) [:2.0.3-] 
    at com.sun.faces.renderkit.html_basic.MenuRenderer.getConvertedValue(MenuRenderer.java:311) [:2.0.3-] 
    at javax.faces.component.UIInput.getConvertedValue(UIInput.java:1023) [:2.0.3-]     at javax.faces.component.UIInput.validate(UIInput.java:953) [:2.0.3-] 
    at javax.faces.component.UIInput.executeValidate(UIInput.java:1204) [:2.0.3-] 
    at javax.faces.component.UIInput.processValidators(UIInput.java:693) [:2.0.3-] 
    at javax.faces.component.UIComponentBase.processValidators(UIComponentBase.java:1081) [:2.0.3-] 
    at javax.faces.component.UIComponentBase.processValidators(UIComponentBase.java:1081) [:2.0.3-] 
    at javax.faces.component.UIComponentBase.processValidators(UIComponentBase.java:1081) [:2.0.3-] 
    at javax.faces.component.UIComponentBase.processValidators(UIComponentBase.java:1081) [:2.0.3-] 
    at javax.faces.component.UIComponentBase.processValidators(UIComponentBase.java:1081) [:2.0.3-] 
    at javax.faces.component.UIForm.processValidators(UIForm.java:240) [:2.0.3-] 
    at org.ajax4jsf.component.AjaxViewRoot$3.invokeContextCallback(AjaxViewRoot.java:439) [:3.3.1.GA] 
    at org.ajax4jsf.component.AjaxViewRoot.processPhase(AjaxViewRoot.java:238) [:3.3.1.GA] 
    at org.ajax4jsf.component.AjaxViewRoot.processValidators(AjaxViewRoot.java:455) [:3.3.1.GA] 
    at com.sun.faces.lifecycle.ProcessValidationsPhase.execute(ProcessValidationsPhase.java:72) [:2.0.3-]   at com.sun.faces.lifecycle.Phase.doPhase(Phase.java:97) [:2.0.3-] 
    at com.sun.faces.lifecycle.LifecycleImpl.execute(LifecycleImpl.java:114) [:2.0.3-] 
    at javax.faces.webapp.FacesServlet.service(FacesServlet.java:308) [:2.0.3-]
    ... 42 more

这是怎么引起的，我该如何解决？

Answer 1

javax.faces.FacesException: Target model Type is no a Collection or Array
    at com.sun.faces.renderkit.html_basic.MenuRenderer.convertSelectManyValuesForModel(MenuRenderer.java:388)

此异常表明您有一个 UISelectMany View 中的组件，例如 <h:selectManyMenu>或 <h:selectManyListbox>其值为未绑定(bind)到集合或数组。这个不对。它的值必须绑定(bind)到一个集合(如 List<Entity> )或数组(如 Entity[] )，因为该组件可以检索多个提交的值。

这里有一个启动示例，说明如何正确地 <h:selectManyMenu>看起来像，假设你正在使用 String输入的项目:

<h:selectManyMenu value="#{bean.selectedItems}">
    <f:selectItems value="#{bean.availableItems}" />
</h:selectManyMenu>
<h:commandButton value="submit" action="#{bean.submit}" />

与

private List<String> selectedItems; // Note: List<String> and thus NOT String!
private List<String> availableItems;

@PostConstruct
public void init() {
    availableItems = Arrays.asList("one", "two", "three", "four", "five");
}

public void submit() {
    System.out.println("Selected items: " + selectedItems);
}

另见:

• How to get all the selected values from h:selectManyListbox in the backend bean in case of JSF?