如果jsf数据表为空，如何显示消息？

Using JSF1.2, if my datatable binding returns no rows I want to display a message saying so.

使用JSF1.2,如果我的数据表绑定没有返回任何行,我想显示一条消息。

How do I do that?

我怎么做?

And for extra points - how do I hide the table completly if it's empty?

而对于额外的积分 - 如果它是空的,我如何完整地隐藏表?

Thanks.

2 个解决方案

#1

Make use of the rendered attribute. It accepts a boolean expression. You can evaluate the datatable's value inside the expression with help of the EL's empty keyword. If it returns false, the whole component (and its children) won't be rendered.

使用呈现的属性。它接受一个布尔表达式。您可以借助EL的空关键字来评估表达式中数据表的值。如果返回false,则不会呈现整个组件(及其子组件)。

<h:outputText value="Table is empty!" rendered="#{empty bean.list}" />

<h:dataTable value="#{bean.list}" rendered="#{not empty bean.list}">
    ...
</h:dataTable>

For the case you're interested, here are other basic examples how to make use of the EL powers inside the rendered attribute:

对于您感兴趣的情况,以下是如何在渲染属性中使用EL功能的其他基本示例:

<h:someComponent rendered="#{bean.booleanValue}" />
<h:someComponent rendered="#{bean.intValue gt 10}" />
<h:someComponent rendered="#{bean.objectValue eq null}" />
<h:someComponent rendered="#{bean.stringValue ne 'someValue'}" />
<h:someComponent rendered="#{not empty bean.collectionValue}" />
<h:someComponent rendered="#{not bean.booleanValue and bean.intValue ne 0}" />
<h:someComponent rendered="#{bean.enumValue eq 'ONE' or bean.enumValue eq 'TWO'}" />

#2

You can test this in several ways, for example by having a function in a bean that tests the list size:

您可以通过多种方式对此进行测试,例如通过在bean中测试列表大小的函数:

function boolean isEmpty() {
    return myList.isEmpty();
}

then in the JSF pages :

然后在JSF页面中:

<h:outputText value="List is empty" rendered="#{myBean.empty}"/>

<h:datatable ... rendered="#{!myBean.empty}">
...
</h:datatable>

#1