In my application I want to display a <h:dataTable> with managed bean properties. Currently this table is created from a List<Folder>. Now I want to change the Folder to something more dynamic. That's because I don't want to change the Folder class if I decide to add another field later. I would just have to add another entry in the Map<String, Object> instead of introducing a new field in Folder.
So, is it possible to bind a List<Map<String, Object>> to the <h:dataTable>?
Is it possible to bind a List of HashMaps to the jsf component h:dataTable?
That's only possible if you generate the necessary <h:column> tags with a view build time tag such as JSTL <c:forEach>.
Here's a concrete kickoff example, assuming that your environment supports EL 2.2:
<h:dataTable value="#{bean.listOfMaps}" var="map">
<c:forEach items="#{bean.listOfMaps[0].keySet().toArray()}" var="key">
<h:column>
#{map[key]}
</h:column>
</c:forEach>
</h:dataTable>
(if your environment doesn't support EL 2.2, you'd need to provide another getter which returns the map key set as a String[] or List<String>; also keep in mind that a HashMap is by nature unordered, you might want to use LinkedHashMap instead to maintain insertion order)
When you're using Mojarra version older than 2.1.18, the disadvantage is that the #{bean} has to be request scoped (not view scoped). Or at least, the <c:forEach items> should refer a request scoped bean. A view scoped bean would otherwise be recreated on every single HTTP request as the <c:forEach> runs during view build time, when the view scope isn't availabe yet. If you absolutely need a view scoped bean for the <h:dataTable>, then you can always create a separate request scoped bean exclusively for <c:forEach items>. The solution would be to upgrade to Mojarra 2.1.18 or newer. For some background information, see also JSTL in JSF2 Facelets... makes sense?
JSF component libraries such as PrimeFaces may offer a <x:columns> tag which makes this more easy, such as <p:dataTable> with <p:columns>.
<p:dataTable value="#{bean.listOfMaps}" var="map">
<p:columns value="#{bean.listOfMaps[0].keySet().toArray()}" var="key">
#{map[key]}
</p:columns>
</p:dataTable>
Related
I need dynamic number of columns. Richfaces supplies it with <rich:columns> in richfaces 3.3.3-final but for Richfaces 4 they seem to recommend <c:forEach>.
c:forEach
I can't get it to work properly.Since I can't depend on the var from the datatable I can't figure out how to feed <c:forEach> with the correct list of columns. (Each row has their own values but headers are the same)
Basically the data I want to display is a list with rows of x size, each row has a list of column values with y size. But how can have <c:forEach> tell the backing bean what row it's at so I can feed the correct columns?
ui/a4j:repeat
I dont want to reinvent the wheel because I need frozen columns and many other features. Creating the table html this way and use jQuery for other features have been considered. However this would be hopeless to maintain and to much work.
I also looked at constructing it from the backing bean creating children dynamically but I don't like that at all. This would have to be the last resort.
Using: Tomcat 7, servlet 3.0, JSF 2.1x - Mojarra, Richfaces 4.x
Update
Okay so I'm getting some results finally. However my headers don't show. The values show perfectly but not the headers. Some problem doing them with iteration or something perhaps?
<rich:dataTable value="#{controller.rows}"
var="row">
<c:forEach items="#{controller.columns}" var="column">
<rd:column id="name" width="250">
<f:facet name="header">
<h:outputText value="#{row.myArrayList[column].header}" />
</f:facet>
<h:inputText value="#{row.myArrayList[column].value}" disabled="#{row.myArrayList[column].open}"/>
</rd:column>
</c:forEach>
</rich:dataTable>
The <c:forEach> is indeed best what you can get. The <ui/a4j:repeat> won't work as that runs during view render time while the UIData component really needs UIColumn children, not UIRepeat children.
In order to get the <c:forEach> to work, you need to supply it a list/map of all property names (and in case of a map maybe also header labels). Here's a concrete kickoff example assuming that Item has properties id, name and value and that #{bean.itemPropertyNames} returns a List<String> with exactly those property names.
<rich:dataTable value="#{bean.items}" var="item">
<c:forEach items="#{bean.itemPropertyNames}" var="itemPropertyName">
<rich:column>
#{item[itemPropertyName]}
</rich:column>
</c:forEach>
</rich:dataTable>
If you need to show column headers as well, then best is to have a Map<String, String> where the key represents the property name and the value represents the header value.
<rich:dataTable value="#{bean.items}" var="item">
<c:forEach items="#{bean.itemProperties}" var="itemProperty">
<rich:column>
<f:facet name="header">#{itemProperty.value}</f:facet>
#{item[itemProperty.key]}
</rich:column>
</c:forEach>
</rich:dataTable>
Either way, the only disadvantage is that the #{bean} of <c:forEach items> can in this construct not be a view scoped one. It would be recreated on every request, unless you turn off partial state saving. It needs to be a request scoped one (or session or application). Note that it does not necessarily need to be the same bean as the one in <rich:dataTable value>.
See also:
Dynamically generate h:column based on list of hashmaps
Is there a way to display a specific JSF page based on the request URL?
Let's say I have a JSF page "details.xhtml". The managed bean "detailsBean" has a list of objects where each object has its own ID. Now if a user requests the page "../details.xhtml?id=1", the list should be queried for an object with ID 1 and the resulting details page of this object should be displayed.
I already wrote a converter implementation class which can convert from object to ID and vice versa, but I don't know how to use it properly. Do I have to work through the JAX-RS specification for this to work or is there a more simple solution?
In JSF you can do this by using a so-called view parameter. You declare these in the metadata section of your Facelet:
<f:metadata>
<f:viewParam name="id" value="#{yourBean.yourObject}" label="id"
converter="yourObjectConverter"
/>
</f:metadata>
This will grab the URL parameter id from the request URL. E.g. if you request the page this appears on with localhost:8080/mypage.jsf?id=1, then 1 will be handed to the yourObjectConverter and whatever this converter returns will be set in yourBean.yourObject.
Your backing bean will thus get the converted object. No need to pollute your backing bean over and over again with the same query code.
#ManagedBean
public class YourBean {
private SomeObject someObject;
public void setYourObject(SomeObject someObject) {
this.someObject = someObject;
}
}
If your backing bean is view scoped, you may want to use the OmniFaces variant of viewParam instead, since otherwise it will needlessly convert after each postback (if your converter does a DB query, you definitely don't want this).
Working full examples:
http://code.google.com/p/javaee6-crud-example/source/browse/WebContent/user_edit.xhtml
http://code.google.com/p/javaee6-crud-example/source/browse/src/backing/UserEdit.java
Further reading:
Communication in JSF 2.0 - Processing GET request parameters
Stateless vs Stateful JSF view parameters
You can achieve this with plain JSF with the following steps
Capture the ID in the request to determine what object is being queried for in your DetailsBean from the request parameter. There are many ways to achieve this, one of which is adding the following annotation to your managed bean (this is currently only permitted for a #RequestScoped bean, see why here).
#ManagedProperty(value="#{param.id}")
int requiredObjectId;
The annotation above will capture the id parameter from the request and assign it to the requiredObjectId variable.
Using the captured Id, setup your object in your bean in a #PostConstruct method
#PostConstruct
public void queryForObject(){
//use the requiredObjectId variable to query and setup the object in the backing bean
}
The object retrieved should be assigned as an instance variable of your managed bean
In your view, you could then reference the queried object that has been setup in the backing bean
<h:panelGrid columns="2">
<h:outputText value="Title"/>
<h:outputText value="#{detailsBean.selectedObject.title}"/>
</h:panelGrid>
If your bean is in a scope broader than the request scope, you'll need a combination of constructs to cleanly pull that request parameter before view rendering.
Capture the request parameter within the JSF view itself using
<f:metadata>
<f:viewParam name="id" value="#{detailsBean.requiredObjectId}" required="true" requiredMessage="You must provide an Object Id"/>
</f:metadata>
**OR**
Due to the nature of JSF Lifecycle processing, doing the above alone may not make the value available for your use in time for object setup. You could use the following instead.
<f:metadata>
<f:event type="preRenderView" listener="#{detailsBean.setObjectId}" />
</f:metadata>
What we've done here is specify a method (that captures the id) in the backing bean that must be executed before the view is rendered, ensuring that the id parameter is available as at the time you need it. Proceed with step 3, only if you're using <f:event/> above.
In the backing bean, you now define the setObjectId method
public void setObjectId(){
Map<String,String> requestParams = FacesContext.getExternalContext().getRequestParameterMap();
requiredObjectId = Integer.parseInt(requestParams.get("id"));
}
Note that the above option is generally a work around/hack and not a clean solution as such
I'm creating a dynamically generated menu. In the database, I have stored the directory (String) of each submenu and stored in an ArrayList in the bean. This is a part of the code:
<c:forEach items="#{controlWeb.algorithms}" var="alg">
<h:form>
<h:commandLink actionListener="#{controlWeb.setContent(PROBLEM)}" value="About"/>
</h:form>
</c:forEach>
The problem is in "PROBLEM". I want to write #{alg.algorithm1} and it doesn't work because I think it isn't posible to nest EL expressions.
The actionListener set the String #{alg.algorithm1} in another String. How can I achieve the requirement?
Use action, not actionListener. The actionListener must be bound to a method which takes ActionEvent as the sole argument, no excuses. Also, an actionListener isn't intented to invoke actions, but to listen on actions (so that you can log it or do some preprocessing task or whatever).
<c:forEach items="#{controlWeb.algorithms}" var="alg">
<h:form>
<h:commandLink action="#{controlWeb.setContent(alg.algorithm)}" value="About"/>
</h:form>
</c:forEach>
Note that passing arguments in EL is only supported since EL 2.2 which is shipped along Servlet 3.0 / Java EE 6. You need to make sure that you're targeting a Servlet 3.0 compatible container with a Servlet 3.0 compatible web.xml.
See also:
Differences between action and actionListener
How to call a method with a parameter in JSF
My least favorite part of coding JSF 2.0 forms has to do with the handing of the id attributes of the various input elements. I am forever having trouble coding the clientID of the target component from within the backing bean, particularly since PrimeFaces tabView now includes the id of the p:tab element as part of the clientID. I waste tons of time coding, testing, then re-coding those clientIDs.
It is reminiscent of older-style assembly language programming where you have to generate tons of label names for your branches and loops. I've done of enough of that for a lifetime.
One approach I am trying is to use only auto-generated id attributes. For example one line of my form might look like this.
<h:outputLabel value="Full Name:" />
<p:inputText value="#{editUser.user.fullName}"
binding="#{editUser.compFullName}"/>
<p:message for="#{editUser.compFullName.clientId}" />
Note that I do not have an explicit id attribute. Then in the backing bean:
String clientID = getCompFullName().getClientId();
msg = new FacesMessage(FacesMessage.SEVERITY_INFO,
"Summary Message For Full Name", "Detail Message Full Name");
FacesContext.getCurrentInstance().addMessage(clientID, msg);
This always works, even if the component has a complex clientID, such as when PrimeFaces inserts the p:tab id into the clientID. (Which it does starting v 3). Rearranging the form never breaks anything.
It is, however, laborious, since I have to create UIComponent properties, getters and setters, and bind them in the form with binding attributes. Can anyone suggest a better way of doing this?
since I have to create UIComponent properties, getters and setters, and bind them in the form with binding attributes. Can anyone suggest a better way of doing this?
It's not required to bind the component to some backing bean if you don't use it in there at all. Just bind it to the view instead:
<p:inputText value="#{editUser.user.fullName}"
binding="#{compFullName}"/>
<p:message for="#{compFullName.clientId}" />
To make the code more self-documenting, I suggest to put a HashMap in the request scope by faces-config.xml:
<managed-bean>
<description>Holder of all component bindings.</description>
<managed-bean-name>components</managed-bean-name>
<managed-bean-class>java.util.HashMap</managed-bean-class>
<managed-bean-scope>request</managed-bean-scope>
</managed-bean>
with
<p:inputText value="#{editUser.user.fullName}"
binding="#{components.fullName}"/>
<p:message for="#{components.fullName.clientId}" />
Adding messages is supposed to be done by a Converter or a Validator which is trowing it as a ConverterException or ValidatorException respectively. It will automatically end up in the right message holder. Or if it are informal messages, just add it on the client ID of the UIComponent which is already available as method argument.
See also:
JSF component binding without bean property
<h:commandButton value="Add Order" action="#{orderBasket.addItems(param['orderItemId'])}"/>
I can't get the above to work...when you click on the button the param seems to get set to null. Is there a way around this?
Is there another way of passing the URL params into the action method? I'm using Spring EL resolver which limits my ability to pass in the parameters into beans as I'm not using faces-config.
First, I think you could use JSF better, a lot of problems would be much simpler. It looks that you are using JSF as a request/response framework, like Struts. JSF is an object oriented component framework, you should use it this way to get the best of it.
I'll try to solve your problem, but I'm missing some information on what you are doing.
If you have a list of books that you can order, let's say they are displayed in a datatable (you could use ui:repeat instead) :
<h:dataTable value="#{bookController.books}" var="book">
<h:column>
<h:outputText value="#{book.title}" />
</h:column>
<h:column>
<h:commandButton value="Add Order" action="#{orderBasket.addItems(book)}" />
</h:column>
</h:dataTable>
In orderBasket backing bean, you simply take a Book (or whatever) as parameter. You don't need to handle the request/response cycle, certainly not in your views.
You can use f:ajax tag if you need to display that in your shopping cart immediately.
Let me know if you need more explanation (backing beans source or else).