Primefaces static and dynamic columns in datatable - jsf-2

Question

I am using Primefaces 5.0 to create a dynamic datatable.
My DataObject has some required fields and a List of optional "tupel" (key-value pair). The optional list may vary in size. Therefore I need a dynamic mechanism to show a List of DataObject in Primefaces.DataTable.
My approach looks like:
public class DataObject {
private String staticval1;
private String staticval2;
private List<Tupel> optionalValues;
// .. getter, setter, hashCode, toString.....
}
public class Tupel{
private String id;
private String value;
}
#ManagedBean
#ViewScoped
public class TableOverviewBean {
private List<DataObject> data;
#EJB
private IMyDao myDao;
#PostConstruct
public void init() {
data = myDao.findAll();
}
public List<DataObject> getData() {
return data;
}
public void setData(List<DataObject> data) {
this.data = data;
}
}
<h:form>
<p:dataTable value="#{tableOverviewBean.data}" var="data">
<p:column headerText="static1">
<h:outputText value="#{data.staticval1}" />
</p:column>
<p:column headerText="static2">
<h:outputText value="#{data.staticval2}" />
</p:column>
<p:columns value="#{data.optionalValues}" var="opt" headerText="#{opt.id}">
<h:outputText value="#{opt.value}" />
</p:columns>
</p:dataTable>
</h:form>
But this does not work. The dynamic columns are not rendered.
How can I solve my problem?
EDIT:
Expected result:
staticval1 | staticval2 | dynamic_id1 | dynamic_id2 | ... | dynmic_idn
----------------------------------------------------------------------
static1a | static2a | dyna_value1a| dyna_value2a | ... | dyna_valu3a
static1b | static2b | dyna_value1b| dyna_value2b | ... | dyna_valu3b
static1c | static2c | dyna_value1c| dyna_value2c | ... | dyna_valu3c

Answer 1

It isn't possible to define columns based on row data. Imagine that row 1 has 2 columns, row 2 has 6 columns, row 3 has 1 column, etc how would you ever produce a technically valid table in HTML? Each row must have the same amount of columns.
You've 2 options, depending on whether can change the model or not:
If you can't change the model, then you need to replace that <p:columns> by a single <p:column> and loop over the #{data.optionalValues} using a nested loop with e.g. <ui:repeat> or perhaps even another <p:dataTable><p:columns>:
<p:column>
<p:dataTable value=""><!-- Empty string as value forces 1 row. -->
<p:columns value="#{data.optionalValues}" var="opt" headerText="#{opt.id}">
#{opt.value}
</p:columns>
</p:dataTable>
</p:column>
If you can change the model, then you need to let <p:columns value> point to a bean property instead of to a row property, so that it's exactly the same for every row. This works if you replace List<Tupel> optionalValues by Map<String, Tupel> optionalValues where the key is Tupel#id and add a List<String> property to the bean containing all available Tupel#id values.
<p:columns value="#{tableOverviewBean.availableTupelIds}" var="id" headerText="#{id}">
#{data.optionalValues[id].value}
</p:columns>

Answer 2

java:
#Named
#ViewScoped
public class LiveRangeService implements Serializable {
private List< Map<String, ColumnModel> > tableData;
private List<ColumnModel> tableHeaderNames;
public List<Map<String, ColumnModel>> getTableData() {
return tableData;
}
public List<ColumnModel> getTableHeaderNames() {
return tableHeaderNames;
}
public void PlayListMB() {
tableData = new ArrayList< Map<String, ColumnModel> >();
//Generate table header.
tableHeaderNames = new ArrayList<ColumnModel>();
for (int j = 0; j < 5; j++) {
tableHeaderNames.add(new ColumnModel("header "+j, " col:"+ String.valueOf(j+1)));
}
//Generate table data.
for (int i = 0; i < 10; i++) {
Map<String, ColumnModel> playlist = new HashMap<String, ColumnModel>();
for (int j = 0; j < 5; j++) {
playlist.put(tableHeaderNames.get(j).key,new ColumnModel(tableHeaderNames.get(j).key,"row:" + String.valueOf(i+1) +" col:"+ String.valueOf(j+1)));
}
tableData.add(playlist);
}
}
static public class ColumnModel implements Serializable {
private String key;
private String value;
public ColumnModel(String key, String value) {
this.key = key;
this.value = value;
}
public String getKey() {
return key;
}
public String getValue() {
return value;
}
}
And XHTML:
<h:form>
<p:dataTable id="tbl" var="result"
value="#{liveRangeService.tableData}"
rendered="#{not empty liveRangeService.tableData}"
rowIndexVar="rowIndex"
>
<f:facet name="header"> header table </f:facet>
<p:column>
<f:facet name="header">
<h:outputText value="序号" />
</f:facet>
<h:outputText value="#{rowIndex+1}" />
</p:column>
<p:columns value="#{liveRangeService.tableHeaderNames}"
var="mycolHeader" columnIndexVar="colIndex">
<f:facet name="header">
<h:outputText value="#{mycolHeader.value}" />
</f:facet>
<h:outputText value="#{result[mycolHeader.key].value}" />
<br />
</p:columns>
</p:dataTable>
</h:form>
That's a example.