java SelectOneMenu 更新其他 SelectOneMenu
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SelectOneMenu updates other SelectOneMenu
提问by thomas.st
I want to update the second SelectOneMenu when I select any item of the first SelectOnMenu. As it is now, I get the values for the SelectOneMenus from a ManagedBean. I guess I've to use AJAX (jquery) to send parameters to the ManagedBean.
当我选择第一个 SelectOnMenu 的任何项目时，我想更新第二个 SelectOneMenu。现在，我从 ManagedBean 获取 SelectOneMenus 的值。我想我必须使用 AJAX (jquery) 将参数发送到 ManagedBean。
<h:form>
<div class="center">
<h:panelGrid id="editTable" columns="2" styleClass="center">
...
<h:outputText value="#{msg.timetable_list_category}" />
<h:selectOneMenu class="category">
<f:selectItems value="#{categoryBackingBean.categorys}" var="c"
itemLabel="#{c.category_Name}" itemValue="#{c.id}" />
</h:selectOneMenu>
<h:outputText value="#{msg.timetable_list_seminarblock}" />
<h:selectOneMenu class="seminarblock">
<f:selectItems value="#{seminarblockBackingBean.seminarblocks}" var="s"
itemLabel="#{s.seminarblock_Name}" itemValue="#{s.seminarblock_Id}" />
</h:selectOneMenu>
...
</h:panelGrid>
...
</div>
</h:form>
回答by Fritz
Actually you can use a ValueChangeListener that is invoked when the value of your selectOneMenu changes:
实际上，您可以使用在 selectOneMenu 的值更改时调用的 ValueChangeListener ：
<h:selectOneMenu class="category" valueChangeListener="#{yourBean.selectOneMenuListener}">
<f:selectItems value="#{categoryBackingBean.categorys}" var="c"
itemLabel="#{c.category_Name}" itemValue="#{c.id}" />
</h:selectOneMenu>
Then, in your bean you have this method:
然后，在你的 bean 中你有这个方法：
public void selectOneMenuListener(ValueChangeEvent event) {
//This will return you the newly selected
//value as an object. You'll have to cast it.
Object newValue = event.getNewValue();
//The rest of your processing logic goes here...
}
To update the page you can either add onchange="submit()"to your <h:selectOneMenu/>. For some partial rendering you can try adding this <f:ajax/>instead of onchange="submit()":
要更新页面，您可以添加onchange="submit()"到您的<h:selectOneMenu/>. 对于某些部分渲染，您可以尝试添加它<f:ajax/>而不是onchange="submit()"：
<h:selectOneMenu class="category" valueChangeListener="#{yourBean.selectOneMenuListener}">
<f:selectItems value="#{categoryBackingBean.categorys}" var="c"
itemLabel="#{c.category_Name}" itemValue="#{c.id}" />
<f:ajax event="change" execute="@form" render="theIdOfTheComponentYouWantToReRender"/>
</h:selectOneMenu>
If I'm not mistaken you'll want to get the id of the element selected in the first menu and populate the second one according to it. Then you can render the other selectOneMenu or, if needed, a panel wrapping a part of your form.
如果我没记错的话，您会想要获取在第一个菜单中选择的元素的 id 并根据它填充第二个。然后，您可以呈现另一个 selectOneMenu，或者，如果需要，可以呈现一个包含表单一部分的面板。
回答by Paulius Matulionis
Primefaceshas a great feature of what you trying to achieve. It already using Ajax, so don't have to worry about writing code your self.
Primefaces有一个很棒的功能，可以帮助您实现目标。它已经在使用 Ajax，所以不必担心自己编写代码。
