multiple component instances in one page

[soudmaijer]

Allright, I might be asking something dumb, but: I have build a simple helloworld application. Below is the component:

@Name("helloworld")
public class Helloworld {

 private DumbUser dumbUser;

 public String sayHello() {
 System.out.println("sayHello");
 return "success";
 }

 public DumbUser getDumbUser() {
 System.out.println("retrieving user");
 return dumbUser;
 }

 public void setDumbUser(DumbUser dumbUser) {
 System.out.println("setting user");
 this.dumbUser = dumbUser;
 }
}

And this simple class

public class DumbUser {

 private String name;

 public DumbUser() {
 }

 public String getName() {
 return name;
 }

 public void setName(String name) {
 this.name = name;
 }
}

This is the JSF page:

 <h:form id="helloworld">
 <div>
 <h:inputText value="#{helloworld.dumbUser.name}"/>
 <h:commandButton type="submit" value="sayHello!" action="#{helloworld.sayHello}"/>
 </div>
 </h:form>

When I hit the button, the helloworld.sayHello is never triggered. I can`t figure out why. helloworld.getDumbUser is called but then execution stops.

Uhm, what am I doing wrong?

[soudmaijer]

I forgot to mention, when I remove the line:

<h:inputText value="#{helloworld.dumbUser.name}"/>

everything works fine.

[sbublava]

Well dumbUser is null, so the value you enter cannot be assigned to dumbUser.name.

Don't you see a NullPointerException in the log file?

[pmuir]

You've forgotten to create an instance of DumbUser in Helloworld

[fernando_jmt]

Because your attribute DumbUser is a plain class (not injected), you sould initialize your class manually,

private DumbUser dumbUser = new DumbUser();

Try above, I think it will work.

[soudmaijer]

"sbublava" wrote:
Well dumbUser is null, so the value you enter cannot be assigned to dumbUser.name.

Don't you see a NullPointerException in the log file?

OMG, i`m an idiot, been working to long today I guess...

Indeed this was the problem, but no nullpointers in the log (strange).

Thnx :)

[sbublava]

"soudmaijer" wrote:

Indeed this was the problem, but no nullpointers in the log (strange).

Then it's probably a regular error message. Try adding:

<h:messages />

[soudmaijer]

Alright,

this works, but now to another problem. Lets say my simple object looks like this:

@Name("dumbUser")
public class DumbUser {

 private String name;

 public DumbUser() {
 }

 public String getName() {
 return name;
 }

 public void setName(String name) {
 this.name = name;
 }
}

and my helloworld component looks like this:

@Name("helloworld")
public class Helloworld {

 @In("dumbUser")
 private DumbUser dumbUser;

 public String sayHello() {
 System.out.println("sayHello: "+ dumbUser.getName());
 return "success";
 }
}

my jsf like this:

 <h:form>
 <div>
 <h:inputText value="#{dumbUser.name}"></h:inputText>

 <h:commandButton type="submit" value="sayHello!" action="#{helloworld.sayHello}"/>
 </div>
 </h:form>

This all works fine, but if I want to add another dumbUser to the Helloworld component, something like this:

@Name("helloworld")
public class Helloworld {

 @In("dumbUser")
 private DumbUser dumbUser1;

 @In("dumbUser")
 private DumbUser dumbUser2;

 public String sayHello() {
 System.out.println("sayHello: "+ dumbUser1.getName());
 System.out.println("sayHello: "+ dumbUser2.getName());
 return "success";
 }
}

Is this possible? How do I access them from the JSF? Something like this?

 <h:form>
 <div>
 <h:inputText value="#{dumbUser1.name}"></h:inputText>
 <h:inputText value="#{dumbUser2.name}"></h:inputText>

 <h:commandButton type="submit" value="sayHello!" action="#{helloworld.sayHello}"/>
 </div>
 </h:form>

This doesnt work... but i`ve tried many variations... is it possible?

[sbublava]

@Name("helloworld")
public class Helloworld {

 @In("dumbUser")
 private DumbUser dumbUser1;

 @In("dumbUser")
 private DumbUser dumbUser2;
}

I believe the second one should be @In("dumbUser2").

[fernando_jmt]

You can try defining a new different role for the second DumbUser.

First you need to modify your dumbClass like this (adding a new role):

@Name("dumbUser")
@Role(name="dumbUser1")
public class DumbUser {

 private String name;

 public DumbUser() {
 }

 public String getName() {
 return name;
 }

 public void setName(String name) {
 this.name = name;
 }
}

Then your hello world component:

@Name("helloworld")
public class Helloworld {

 @In("dumbUser")
 private DumbUser dumbUser1;

 @In("dumbUser1")
 private DumbUser dumbUser2;

 public String sayHello() {
 System.out.println("sayHello: "+ dumbUser1.getName());
 System.out.println("sayHello: "+ dumbUser2.getName());
 return "success";
 }
}

Then the JSF should looks like:

<h:form>
 <div>
 <h:inputText value="#{dumbUser.name}"></h:inputText>
 <h:inputText value="#{dumbUser1.name}"></h:inputText>

 <h:commandButton type="submit" value="sayHello!" action="#{helloworld.sayHello}"/>
 </div>
 </h:form>

[soudmaijer]

"sbublava" wrote:

@Name("helloworld")
public class Helloworld {

 @In("dumbUser")
 private DumbUser dumbUser1;

 @In("dumbUser")
 private DumbUser dumbUser2;
}

I believe the second one should be @In("dumbUser2").

Tried this, but that doesn`t work.... (thanks for the suggestion)

[sbublava]

Do you need exactly two DumbUser instances or many of them?

[soudmaijer]

"fernando_jmt" wrote:
You can try defining a new different role for the second DumbUser.

Cool, this works!

So it means, that if you want to have multiple occurences of an component in one page, you can`t do this without modifying the component (This surprises me a bit).

Thnx all for the responses.

[soudmaijer]

"sbublava" wrote:
Do you need exactly two DumbUser instances or many of them?

I was just testing around a bit. If I need multiple instances I would probably store it in a collection.

But in this particular case I was trying to let seam inject two instances of an component for me.

[norman.richards]

You can also declare the second named instance in XML. It has to be declared somewhere.