Is it possible to do dynamic column ordering on a p:dataTable without using p:columns? - jsf

Question

I'm trying to dynamically display the columns of a p:dataTable: the server dictates which columns are displayed and in which order. It doesn't look like I can set a dynamic order using the regular p:column tag so I'm stuck using the p:columns tag. The problems with the p:columns tag are:
1) The example in the showcase shows it working with String data, where you can map a column name to a field and then use an expression language map to retrieve the data (like a pseudo-getter)
http://www.primefaces.org/showcase/ui/data/datatable/columns.xhtml
If I have different data types though, then I'm probably stuck with a bunch of panels with render attributes based on the type of the data (display Strings one way, display User objects another way, etc).
Example:
<p:dataTable value="#{myBean.rows}" var="row">
<p:columns value="#{myBean.columns}" var="column">
<f:facet name="header">
<h:outputText value="#{column.header}" />
</f:facet>
<!-- The content of the cell is dynamic based on the type of the field -->
<!-- display a String field -->
<h:outputText rendered="#{myBean.isStringType(column.header)}"
value="#{row[column.property]}"/>
<!-- display a Person field -->
<h:outputText rendered="#{myBean.isPersonType(column.header)}"
value="#{row[column.property].name}, #{row[column.property].email}"/>
</p:columns>
</p:dataTable>
2) p:columns only supports a single sortFunction/filterFunction for all columns. Since these columns all have different types of data, they will require many different sorting and filtering methods
A p:column easily allows for the display of different data types as well as the sorting/filtering of the data. The only thing it can't do is have a dynamic order.
Unless I'm missing something? Is there a way to get this to work with p:column ? Or is there an elegant way to have p:columns handle all of this?

Answer 1

It doesn't look like I can set a dynamic order using the regular p:column tag so I'm stuck using the p:columns tag.
If the #{myBean.columns} columns model is constant during at least the view scope, then you'd better use <c:forEach><p:column><c:choose>. It's faster than <p:columns>+rendered, and allows more dynamic freedom as you can declare every <p:column> individually depending on the type instead of having only one <p:columns> whose state changes every iteration round.
<p:dataTable value="#{myBean.rows}" var="row">
<c:forEach items="#{myBean.columns}" var="column">
<c:choose>
<c:when test="#{column.type eq 'STRING'}">
<p:column sortBy="#{row[column.property]}" filterBy="#{row[column.property]}">
#{row[column.property]}
</p:column>
</c:when>
<c:when test="#{column.type eq 'PERSON'}">
<p:column sortBy="#{row[column.property].name}" filterBy="#{row[column.property].name}">
#{row[column.property].name}, #{row[column.property].email}
</p:column>
</c:when>
...
</c:choose>
</c:forEach>
</p:dataTable>
See also:
JSTL in JSF2 Facelets... makes sense?
How to create dynamic JSF form fields