I'm studying a code and I'm not understanding this excerpt from EL:
<c:choose>
<c:when test="${not empty pedidoMesa}">
Pedido: ${pedidoMesa.id} ${pedidoMesa.nomeCliente}
</c:when>
<c:otherwise>
Mesa
</c:otherwise>
</c:choose>
As this pedidoMesa was referenced, to show id and nomeCliente ? I turned and rolled the code and found nothing that could relate to Model.
In summary:
<c:choose> in expression language is like a switch/case in your Java code.
The <when test="{condição}"> is like case "condição": .
And <c:otherwise> is equivalent to default within a switch/case structure.
Notice that the core of JSTL does not have a <c:else> condition, ie if you need to test a condition and then take an action in case it is false, you would have to do something like this:
<c:if test="${not empty pedidoMesa}">
Pedido: ${pedidoMesa.id} ${pedidoMesa.nomeCliente}
</c:if>
<c:if test="${empty pedidoMesa}">
Mesa
</c:if>
It's okay to write code like this, but some developers prefer to use <c:choose> (which is equivalent to switch/case ) and make use of <c:otherwise> to treat the opposite condition within a same structure. The above code could be written like this:
<c:choose>
<c:when teste="${not empty pedidoMesa}">
Pedido: ${pedidoMesa.id} ${pedidoMesa.nomeCliente}
</c:when>
<c:otherwise>
Mesa
</c:otherwise>
</c:choose>
When you use ${pedidoMesa} , the first attribute named pedidoMesa that is not null will be returned, no matter in what context the request was created / defined. However, in the following order: PageContext , HttpServletContext , HttpSession and ServletContext .