Iterating through List<Map<String, String>> in primefaces datatable? - jsf

I'm trying to iterate through a List of Map items, i.e. an ArrayList of HashMaps or something similar, and I'm trying to do this in primefaces datatable. This is basically what I'm trying to do:
<body>
<h:form>
<p:dataTable value="#{customerBean.list}" var="map">
<c:forEach items="#{map}" var="entry">
<p:column headerText="#{entry.key}">
#{entry.value}
</p:column>
</c:forEach>
</p:dataTable>
</h:form>
</body>
In this case, customerBean.list is a List<Map<String, String>> and entry is a Map<String, String>.
What I want to do, is create a dynamic amount of columns, based on the amount of entries in a Map<String, String> while using the map entry's key as a header name, and the value as the output. The c:forEach thing seems to work fine when I'm using a hardcoded Map<String, String>, but apparently it can't loop through the var of the p:dataTable. I assume that the program takes precaution to avoid having to loop through Maps of different sizes. So how can I make this work anyway? How can I create an arbitrary amount of columns based on the amount of entries in a Map? Note that I'm a 100% certain that every Map<String, String> is of equal size in my List<Map<String, String>>
EDIT:
Here's my bean source. The code works fine and everything, the problem is just with the loop not willing to go through my map:
#ManagedBean
#SessionScoped
public class CustomerBean {
private List<Map<String, String>> list = new ArrayList<Map<String, String>>();
private Mapper mapper = new Mapper();
public CustomerBean() {
list = mapper.all(); //gets data from database
}
public List<Map<String, String>> getList() {
return list;
}
public void setList(List<Map<String, String>> list) {
this.list = list;
}
}

The problem is unrelated to the Map usage in this context. The problem is that you're trying to get a #{map} variable that's only available when view is being rendered, but you're relying on its value at the moment when view is being built. The latter is performed on an earlier lifecycle phase, so it is basically unavailable when you demand it.
Still, tag handler, or view build tag, like <c:forEach>, is the only way to populate the variable number of columns, as <p:column> is assessed when component tree is being built.
Another thing worth noting is that the backing bean bound to <c:forEach> tag's property, such as items, must be anything but view scoped, like request scoped, otherwise it will be recreated upon every request which will bring unexpected/undesired results, as the demanded bean is not there when you try to access its properties. There are some other setup constellations solving this issue, but they're not the subject of discussion here.
<p:dataTable value="#{customerBean.list}" var="map">
<c:forEach items="#{forEachBean.columnsMap}" var="entry">
<p:column headerText="#{entry.key}">
#{map[entry.key]}
</p:column>
</c:forEach>
</p:dataTable>
Also worth noting that there is a helper <p:columns> component that does roughly the same.

Related

Primefaces datatable's p:columns not iterating over Map

I am having a two level map Map<String,HashMap<String,String>> which i need to display using a <p:dataTable>. The code of managed bean is as follows:
#ManagedBean(name="MyBean")
public class MyBean{
private Map<String,HashMap<String,String>> twoDimentionalMap;
public void getMapData(){
twoDimentionalMap=getDataFromDataStore();
}
}
Now I am using this map in my view.xhtml file as follows:
<p:dataTable var="entrySet1" value="#{MyBean.twoDimentionalMap.entrySet()}">
<p:columns var="entrySet2" value="#{entrySet1.getValue()}">
#{entrySet2.getKey()} - #{entrySet2.getValue()}
</p:columns>
</p:dataTable>
I also tried using
<p:dataTable var="entrySet1" value="#{MyBean.twoDimentionalMap.entrySet()}">
<p:columns var="entrySet2" value="#{MyBean.twoDimentionalMap.get(entrySet1.getKey()).getValue()}">
#{entrySet2.getKey()} - #{entrySet2.getValue()}
</p:columns>
</p:dataTable>
I even tried converting the outer map to a list:
List<HashMap<String,String>> twoDimentionalMap;
However nothing is displayed on datatable. The execution shows no error but there is nothing displayed on the page.
Kindly suggest if I am doing something wrong or if <p:columns> is having any issue handling maps.
Thanks
since the keys of outer map do not have a meaning, converting the outer map to a list is correct.
but your approach to retrieve column names from xhtml does not seem valid. you need to get them independently from the current iteration variable entrySet1, otherwise you add a third dimension to the operation, which data table cannot handle.
we need to assume that all keys are same across the listed maps.
here is the code for xhtml:
<p:dataTable var="entrySet1" value="#{testMB.twoDimensionalMap}">
<p:columns var="keySet2" value="#{testMB.columnNames}">
#{keySet2} - #{entrySet1[keySet2]}
</p:columns>
</p:dataTable>
and for the bean:
#Named
#ViewScoped
public class TestMB implements Serializable {
private List<HashMap<String,String>> twoDimensionalMap;
public TestMB()
{
getMapData();
}
private void getMapData(){
//twoDimentionalMap=getDataFromDataStore();
twoDimensionalMap = new ArrayList<HashMap<String,String>>();
twoDimensionalMap.add(new HashMap<String,String>());
twoDimensionalMap.get(0).put("key0", "value00");
twoDimensionalMap.get(0).put("key1", "value01");
twoDimensionalMap.add(new HashMap<String,String>());
twoDimensionalMap.get(1).put("key0", "value10");
twoDimensionalMap.get(1).put("key1", "value11");
}
public Set<String> getColumnNames()
{
return twoDimensionalMap.size() > 0 ? twoDimensionalMap.get(0).keySet() : new HashSet<String>();
}
public List<HashMap<String, String>> getTwoDimensionalMap() {
return twoDimensionalMap;
}
}

Is #Produces more efficient that a getter in an EL expression

I'm wondering which of those two code snippets is more efficient.
First one
In userSearch.xhtml :
<rich:dataTable
var="user"
value="#{userSearchResultList}"
rendered="#{not empty userSearchResultList}">
...
</rich:dataTable>
In UserSearchAction.java :
#Produces #RequestScoped
#Named("userSearchResultList")
public List<User> getResultList() {
return resultList;
}
Second one
In userSearch.xhtml :
<rich:dataTable
var="user"
value="#{userSearchAction.resultList}"
rendered="#{not empty userSearchAction.resultList}">
...
</rich:dataTable>
In UserSearchAction.java :
public List<User> getResultList() {
return resultList;
}
In both solutions, my resultList variable is filled by a method UserSearchAction.search().
I'm using JBoss 7.0.2.Final and RichFaces 4.1.0.Final.
More generally, I wanted to know if it's better to write producers than to call sub-properties of some classes in JSF files.
That depends on how your producer scopes what is being produced. If it's dependent scoped (meaning you don't have a scope on it, nor on the containing class) it ends up being the same, possibly less depending what it is you are having to do inside that method.
In your example it should be more efficient because that producer method should only be called once (per request).

Getting same instance of `componentType` in composite component on every use

Hi Have this Wierd Issue in which I am using a Composite Component which I wrote and I get values from the previous use of the backing bean of the CC (the componentType bean)
I don't know how to describe this better than just show the code.
I'll try to be brief about it and cut the redundant parts:
This is the Composite Component definition:
<cc:interface componentType="dynamicFieldGroupList">
<cc:attribute name="coupletClass" />
<cc:attribute name="form" default="#form"/>
<cc:attribute name="list" type="java.util.List" required="true"/>
<cc:attribute name="fieldNames" type="java.util.List" required="true" />
</cc:interface>
<cc:implementation>
<h:dataTable value="#{cc.model}" var="currLine">
<h:column>
<h:outputText id="inner_control_component" value="Inner Look at currLine:#{currLine}"/>
</h:column>
</h:dataTable>
</cc:implementation>
The CC bean defintion:
#FacesComponent(value = "dynamicFieldGroupList")
// To be specified in componentType attribute.
#SuppressWarnings({ "rawtypes", "unchecked" })
// We don't care about the actual model item type anyway.
public class DynamicFieldGroupList extends UIComponentBase implements
NamingContainer
{
private transient DataModel model;
#Override
public String getFamily()
{
return "javax.faces.NamingContainer"; // Important! Required for
// composite components.
}
public DataModel getModel()
{
if (model == null)
{
model = new ListDataModel(getList());
}
return model;
}
private List<Map<String, String>> getList()
{ // Don't make this method public! Ends otherwise in an infinite loop
// calling itself everytime.
return (List) getAttributes().get("list");
}
}
And the use code:
<ui:repeat var="group" value="#{currentContact.detailGroups}">
<h:panelGroup rendered="#{not empty group.values}">
<h:outputText id="controlMsg" value=" list:#{group.values}" /><br/><br/>
<utils:fieldTypeGroupList list="#{group.values}"
fieldNames="#{group.fields}" coupletClass="utils" />
</h:panelGroup>
</ui:repeat>
The text of id controlMsg displays the correct values in #{group.values} while the control output inside the component of id inner_control_component shows the values from the previous use.
The values are correct the first time...
I guess it's a fundemental error in use of a CC bean, otherwise it could be a bug with MyFaces 2.1 (Which I'm using)
The explanation for this behaviour is simple: there's only one component definied in the view. So there's also only one backing component with one model. Since the model is lazily loaded on first get, the same model is been reused in every iteration of a parent iterating component.
The <ui:repeat> doesn't run during view build time (as JSTL does), but during view render time. So there are physically not as many components in the view as items which are iterated by <ui:repeat>. If you were using <c:forEach> (or any other iteration tag which runs during view build time), then the composite component would have behaved as you'd expect.
You would like to change the way how the datamodel is kept in the backing component. You would like to preserve a separate datamodel for each iteration of a parent iterating component. One of the ways is to replace the model property as follows:
private Map<String, DataModel> models = new HashMap<String, DataModel>();
public DataModel getModel() {
DataModel model = models.get(getClientId());
if (model == null) {
model = models.put(getClientId(), new ListDataModel(getList()));
}
return model;
}
See also:
What's the view build time?
The problem described here is an old known isse in JSF, hidden by the usage of composite components. It is so important and so difficult, that instead answer here I create a detailed answer in a blog entry for this one: JSF component state per row for datatables
To keep this answer short, I'll say to you it is not a bug in MyFaces 2.1. Please use 2.1.1, because that is a quick bug fix version of 2.1.0. In JSF 2.1 there is a new property for h:dataTable called rowStatePreserved, and this scenario is just one case where "this little baby" becomes useful. Just replace ui:repeat with h:dataTable and add rowStatePreserved="true". That will do the trick. If you need to manipulate the model (add or remove rows) you can use tomahawk t:dataTable and t:dataList, but you will have to take an snapshot version for now. Note this is new stuff not available in any different JSF framework an the moment (JUN 2011).
If you need more info, keep tuned with MyFaces Team on Twitter or ask to the experts on MyFaces Users and Dev Mailing Lists.

Display key and value of HashMap entries in JSF page

I would like to display HashMap keys and its associated value in the JSF UI.
How can I achieve this? How can I iterate over a HashMap in JSF page using some iterator component like <h:datatable>?
Only <c:forEach> supports Map. Each iteration gives a Map.Entry instance back (like as in a normal Java for loop).
<c:forEach items="#{yourBean.map}" var="entry">
<li>Key: #{entry.key}, value: #{entry.value}</li>
</c:forEach>
The <h:dataTable> (and <ui:repeat>) only supports List (JSF 2.2 will come with Collection support). You could copy all keys in a separate List and then iterate over it instead and then use the iterated key to get the associated value using [] in EL.
private Map<String, String> map;
private List<String> keyList;
public void someMethodWhereMapIsCreated() {
map = createItSomeHow();
keyList = new ArrayList<String>(map.keySet());
}
public Map<String, String> getMap(){
return map;
}
public List<String> getKeyList(){
return keyList;
}
<h:dataTable value="#{yourBean.keyList}" var="key">
<h:column>
Key: #{key}
</h:column>
<h:column>
Value: #{yourBean.map[key]}
</h:column>
</h:dataTable>
Noted should be that a HashMap is by nature unordered. If you would like to maintain insertion order, like as with List, rather use LinkedHashMap instead.
With <ui:repeat> (JSF 2.2 and onwards):
<ui:repeat var="entry" value="#{map.entrySet().toArray()}">
key:#{entry.key}, Id: #{entry.value.id}
</ui:repeat>
Source: https://gist.github.com/zhangsida/9206849

JSF: How to bind many of h:selectBooleanCheckbox?

I have a problem to bind list of h:selectBooleanCheckbox to my bean.
Anybody helps ?
This is not working:
<ui:repeat value="#{cartBean.productsList}" var="cartProduct" varStatus="i">
<h:selectBooleanCheckbox binding="#{cartBean.checkboxes[i.index]}" />
</ui:repeat>
public class CartBean extends BaseBean {
public List<Product> getProductsList() {...}
private HtmlSelectBooleanCheckbox[] checkboxes;
public HtmlSelectBooleanCheckbox[] getCheckboxes() {
return checkboxes;
}
public void setCheckboxes(HtmlSelectBooleanCheckbox[] checkboxes) {
this.checkboxes = checkboxes;
}
}
I get error:
javax.faces.FacesException: javax.el.PropertyNotFoundException: /WEB-INF/flows/main/cart.xhtml #26,97 binding="#{cartBean.checkboxes[i.index]}": Target Unreachable, 'checkboxes' returned null
I solved my problem. I used code like below and get what i want (thanks to BalusC blog - http://balusc.blogspot.com/2006/06/using-datatables.html#SelectMultipleRows):
<ui:repeat value="#{cartBean.productsList}" var="cartProduct" varStatus="i">
<h:selectBooleanCheckbox value="#{cartBean.selectedIds[cartProduct.id]}" />
</ui:repeat>
public class CartBean extends BaseBean {
private Map<Integer, Boolean> selectedIds = new HashMap<Integer, Boolean>();
public Map<Integer, Boolean> getSelectedIds() {
return selectedIds;
}
}
Your concrete problem is caused because the binding attribute is evaluated during view build time, that moment when the XHTML source code is turned into a JSF UI component tree, while the <ui:repeat> runs during view render time, that moment when the JSF UI component tree needs to produce HTML.
In other words, the #{i.index} is only available during view render time and evaluates as null during view build time. In effects, you're doing a binding="#{cartBean.checkboxes[null]}"
There's another conceptual mistake here: you seem to expect that the <ui:repeat> produces physically multiple <h:selectBooleanCheckbox> components. This is untrue. There's physically only one <h:selectBooleanCheckbox> which is reused multiple times to produce HTML based on the currently iterated variable. Actually, binding="#{cartBean.checkbox}" was been sufficient. However, collecting the values is a story apart. I won't go in detail, but you can find several hints in this answer: Validate order of items inside ui:repeat.
In order to achieve the (apparent) concrete functional requirement of generating physically multiple <h:selectBooleanCheckbox> components and binding each to a separate array item, you should be using an iteration component which runs during view build time instead of view render time. That's the JSTL <c:forEach>:
<c:forEach items="#{cartBean.productsList}" var="cartProduct" varStatus="i">
<h:selectBooleanCheckbox binding="#{cartBean.checkboxes[i.index]}" />
</c:forEach>
But, after all, using binding on a bean property should be avoided as much as possible. Use instead exactly that attribute which you ultimately need: the value attribute. This way you don't need to do a HtmlSelectBooleanCheckbox#getValue() everytime. You already figured the right solution with a Map<Integer, Boolean> selectedIds:
<ui:repeat value="#{cartBean.productsList}" var="cartProduct">
<h:selectBooleanCheckbox value="#{cartBean.selectedIds[cartProduct.id]}" />
</ui:repeat>
See also:
JSTL in JSF2 Facelets... makes sense?
I don't know if you can bind elements stored in an array. But in your code, the problem is that your HtmlSelectBooleanCheckbox[] is null. So maybe change your Java code to:
public HtmlSelectBooleanCheckbox[] getCheckboxes() {
if (checkboxes == null) {
checkboxes = new HtmlSelectBooleanCheckbox[getProductsList().size()];
}
return checkboxes;
}
but I am really not sure if it will work... Maybe the solution is to not bind your HtmlSelectBooleanCheckbox elements in the Java code. Why do you need to bind them?

Resources