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Let's say that I have an application which manages users. You can add new user, delete them, edit detail etc. Each user has na ID and has detail page on URL like this:
..../user/detail.jsf?id=123
Now, what should happen if user with ID 123 does not exists? I think that natural reaction would be 404 standard error. Exactly the same as is outputed when you make some typo in URL (like /user/dtail.jsf). So the question is: is there such method?
Or maybe is this reaction (404) appropriate?
Thanks.
552
Just attach a validator to the id view parameter and if validation fails, set error code 404 on the response.
e.g.
Consider this simple Facelet:
<html xmlns="http://www.w3.org/1999/xhtml"
xmlns:h="http://java.sun.com/jsf/html"
xmlns:f="http://java.sun.com/jsf/core">
<f:metadata>
<f:viewParam id="id" name="id" value="#{myBean.id}" validator="#{myBean.validate}"/>
</f:metadata>
<h:body>
<h:outputText value="#{myBean.id}"/>
</h:body>
</html>
And the following backing bean:
@ManagedBean
@ViewScoped
public class MyBean {
private Long id;
public void validate(FacesContext context, UIComponent component, Object object) {
// Do some validation
// And if failed:
context.getExternalContext().setResponseStatus(404);
context.responseComplete();
}
public Long getId() {
return id;
}
public void setId(Long id) {
this.id = id;
}
}
(I ended up here searching for something similar but here's another pattern I used on a similar problem)
The Validation/ExternalContext response above is a very good way to handle it, alternatively (since you are already inside the context) you can handle the error when parsing in the parameters from the request and deal with it internally. I think it is more of how you want to handle it in your flow than a "here's a better solution"
//Inside "SomeManagedBean"
public String getParam()
{
String value = (String) FacesContext.getCurrentInstance().getExternalContext().getRequestParameterMap().get("key");
if(value == null)
return "key not Exist";
else
return value;
}
//JSF 2.0 Source (something.xhtml) ... ...
I think the above is generally easier to work with inside the framework (you don't have to send out to an error page and disrupt the flow), but really it is simply an architectural decision. Both solutions are similar, it is just a question of breaking the flow or internal handling. Either way the ExternalContext is your friend.
22
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