I am trying to pass an object from one page to another page where each page is in a different view.
On the first page I have an input text, where myBean is a ViewScoped Bean and name is an object.
<h:inputText value="#{myBean.name}"/>
The second page contains,
<f:metadata>
<f:viewParam name="userId" value="#{myBean.name}"/>
</f:metadata>
I get the error Conversion Error setting value mypackage.myBean@257100b' for 'null Converter'. Can we pass objects other than String values to view parameters?
Yes, you can. You just have to supply a converter which converts between the string representation of the object type behind #{myBean.name}
and the real object. The string representation is usually the unique technical/natural identifier of the object in question. For example, the table's PK. It has got to be a string, simply because HTTP request parameters can be strings only. You can't pass complex Java objects around in URLs. URLs are just strings.
Here's a kickoff example:
E.g. the following in the initial view:
<h:link value="Edit" outcome="edit">
<f:param name="id" value="#{personViewer.person.id}" />
</h:link>
(which generates an <a href="edit.xhtml?id=123">Edit</a>
)
and the following in the linked view:
<f:metadata>
<f:viewParam name="id" value="#{personEditor.person}"
converter="#{personConverter}" converterMessage="Bad request. Unknown person."
required="true" requiredMessage="Bad request. Please use a link from within the system."
/>
</f:metadata>
<h:messages />
with this converter
@ManagedBean
@RequestScoped
public class PersonConverter implements Converter {
@EJB
private PersonService personService;
@Override
public String getAsString(FacesContext context, UIComponent component, Object value) {
return String.valueOf(((Person) value).getId());
}
@Override
public Object getAsObject(FacesContext context, UIComponent component, String value) {
return personService.find(Long.valueOf(value));
}
}
(oversimplified; all null/number checks omitted, but you got the idea)
Update as per the comments, you actually want to fire a POST request. You don't need a <f:viewParam>
at all. It's for setting/validating/converting GET request parameters only. Attempting to serialize the whole object makes also no utter sense. Just use @ManagedProperty
.
E.g.
@ManagedBean
@ViewScoped
public class PersonEditor implements Serializable {
@ManagedProperty("#{personViewer.person}")
private Person person;
// ...
}
It's only not bookmarkable anymore and not SEO-friendly (but that's the nature of POST, you're probably already for long aware of this). Note that the #{personViewer}
bean must by itself also be @ViewScoped
(and thus not @ReqestScoped
). You also need to make sure that you don't navigate back with a redirect, but just a forward.