Using JSF1.2, if my datatable binding returns no rows I want to display a message 开发者_运维知识库saying so.
How do I do that?
And for extra points - how do I hide the table completly if it's empty?
Thanks.
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.
<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:
<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'}" />
See also:
- Java EE 7 tutorial - Expression Language - Operators
You can test this in several ways, for example by having a function in a bean that tests the list size:
function boolean isEmpty() {
return myList.isEmpty();
}
then in the JSF pages :
<h:outputText value="List is empty" rendered="#{myBean.empty}"/>
<h:datatable ... rendered="#{!myBean.empty}">
...
</h:datatable>
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