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Tapestry - how to get other component's field

I have a tapestry class which loads a variable
public class Component1 {
Object onActionFromEdit(MyClass object){
String param = object.getMyParam();
...}
}
I would like to access the param value from other component.
What is the best way to get it?
Is there some common context where I could store variables?
I tried to search the documentation but had no luck so far.

Difficult to guess, but judging by the name onActionFromEdit may be event handler for EventLink where parameter is passed in HTTP GET request as a query param.
If that's the case there are several ways of sharing event context with other components/parts of the app:
Component parameters - they are actually bi-directional bindings, assigning parameter field from component will write the value to where the parameter was bound. Of course the value will only be available in the scope of current request unless either the fields or associated bindings were annotated with #Persist
class Component1 {
#Parameter MyClass param1;
onActionFromEdit(MyClass object) {
param1 = object; // this will update value of a binding
// where this parameter is set
}
}
If you want to share state with parent component, then you could also #InjectComponent Component1 component1 in parent and access its state directly as with regular java objects, e.g. component1.getState1(), of course this has to be done after event handler assigned the value from request.
Environmental services. This is a per-request service, it's often user by parent components pushing state for child/nested components during rendering/event handling, e.g. t:Form and t:TextField.
It's always possible to create a dedicated per-thread service for concrete use-case and #Inject it where needed. The service may hold shared state in own fields, it will be discarded at the end of the request. The service may also register a cleanup listener in case you need custom logic for end of request cleanup.
Again, difficult to tell why you need this/what's your use-case, but Tapestry pages support activation contexts. Each event link will have this context transparently added, so each time event link is called, containing page will be activated with the stored context and it's then possible to publish this state for components, e.g. using regular component parameters, or one of the methods mentioned above. Jumpstart examples for onActivate/onPassivate.
It's also worth mentioning the #ActivationRequestParameter, you can find more usage examples in the JumpStart.
There's also Session Storage if you need to capture data and share it with other parts of the app in multiple requests. But it sounds too much for your question.
There are other, non-tapestry, ways of sharing data that also work in Tapestry apps, e.g. request attributes, query parameters, etc. But you normally don't use them.

I think you are looking for the ComponentResources class which will allow you to do the following:
public class Component1 {
#Inject
private ComponentResources resources;
Object onActionFromEdit(){
MyComponent comp = (MyComponent) resources.getEmbeddedComponent("ComponentId");
String param = comp.getMyParam();
}
}
If the component is not embedded but part of a sibling, you can also resources.getContainerResources().getEmbeddedComponent("ComponentId") or even fetch it from the page like so: resources.getPage().getComponentResources().getEmbeddedComponent("ComponentId")

Java - Basic for each loop with JSTL

I'm really new to JSTL and having trouble grasping exactly how for each loops work. But say in my java bean I have a very simple while loop, that goes through and grabs properties of an object. I get the expected output from the loop when I log it. Which is simply a string that looks something like headerTest, headerMetaTest. Here is the code from my java bean:
Iterator<Resource> serviceList = null;
serviceList = resource.getChild("header").listChildren();
while(serviceList.hasNext()){
Resource child = serviceList.next();
headerTitle = child.adaptTo(ValueMap.class).get("headerTitle", "");
headerMeta = child.adaptTo(ValueMap.class).get("headerMeta, "");
}
However when I try to access it in the JSTL I'm getting nothing:
<c:forEach var="child" items="${serviceList}">
<p>${child.headerTitle}</p>
<p>${child.headerMeta}</p>
</c:forEach>
The puzzling part is I get no errors, nothing simply returns. Any ideas? Really, really lost on this one and any help is greatly appreciated. I'm a newb to this so code samples are a good way for me to learn and would be great if possible.

There are four scopes to be aware of in JSP pages.
page, request, session and application.
JSTL tags will usually look for attributes in that order.
page maps to attributes assigned during the processing of the page, these are usually quite
rare.
request is for attributes assigned to the ServletRequest, they are the most common
attributes to use as they last for the page request duration, and are then discarded.
eg
public void processMyServlet(ServletRequest request, ServletResponse){
...
request.setAttribute("myAttribute",attributeValue);
...
}
session is for attributes assigned to the HttpSession. This is useful for
user values that are used often during the user session.
eg
public void processMyServlet(HttpServletRequest request, HttpServletResponse){
...
request.getSession().setAttribute("myAttribute",attributeValue);
...
}
application is for attributes assigned to the ServletContext, this is useful for
values that are consistent across the application and do not change.
eg
public void processMyServlet(HttpServletRequest request, HttpServletResponse){
...
request.getServletContext().setAttribute("myAttribute",attributeValue);
...
}
If you are calling a servlet that dispatches your jsp then at the very least you will need.
request.setAttribute("serviceList",myResourceCollection);
somewhere during the servlet processing.
if you are doing everything in jsp then you will need something like
<% java code to create collection
request.setAttribute("serviceList",myResourceCollection);
%>

Using String array "constant" in Spring #RequestMapping value

I should probably point out that Spring is not in and of itself necessarily crucial to this question, but I encountered this behavior while using Spring, so the question uses the situation in Spring in which I encountered this.
I have a controller class that maps requests for GET and POST requests to the same set of URLs for a particular form. This form has different URLs for different locales, but there is only one method for the GET request, and one for the POST, since the logic at the controller level for the form is identical for each locale site (but things deeper in the logic, like locale-specific validation, may be different). Example:
#Controller
public class MyFormController {
// GET request
#RequestMapping(value={"/us-form.html", "/de-form.html", "/fr-form.html"},
method={RequestMethod.GET})
public String showMyForm() {
// Do some stuff like adding values to the model
return "my-form-view";
}
// POST request
#RequestMapping(value={"/us-form.html", "/de-form.html", "/fr-form.html"},
method={RequestMethod.POST})
public String submitMyForm() {
// Do stuff like validation and error marking in the model
return "my-form-view"; // Same as GET
}
}
The form GET and POST works just fine when written like this. You'll notice that the String arrays used for the #RequestMapping values are identical. What I want to do is put those URLs into one spot (ideally a static final field in the controller) so that when we add new URLs (which correspond to the form in future localized sites), we can just add them in one spot. So I tried this modification to the controller:
#Controller
public class MyFormController {
// Moved URLs up here, with references in #RequestMappings
private static final String[] MY_URLS =
{"/us-form.html", "/de-form.html", "/fr-form.html"};
// GET request
#RequestMapping(value=MY_URLS, // <-- considered non-constant
method={RequestMethod.GET})
public String showMyForm() {
// Do some stuff like adding values to the model
return "my-form-view";
}
// POST request
#RequestMapping(value=MY_URLS, // <-- considered non-constant
method={RequestMethod.POST})
public String submitMyForm() {
// Do stuff like validation and error marking in the model
return "my-form-view"; // Same as GET
}
}
The problem here is that the compiler complains about the value attribute no longer being a constant. I am aware that Spring requires that value must be a constant, but I had thought that using a final field (or static final in my case) with an Array literal containing String literals would have passed as "constant". My suspicion here is that the array literal has to be constructed on the fly in such a way that it is uninitialized when the value attribute is parsed.
I feel like this shouldn't be a hard thing to figure out with a basic Java knowledge, but something is escaping me that I haven't been able to find any answers for after some research. Can someone confirm my suspicion and give a citation or good explanation for why that may be so, or deny my suspicion and explain what the actual issue is?
Note: I cannot simply combine the URLs into a Path Pattern, as each form URL is in its localized site's language, and matching on that would be impossible. I merely give the "/{locale}-form.html" strings above as my URLs for example's sake.

You're right, this is nothing to do with Spring, all Annotation parameters must be compile-time constants. That's a basic java language rule.
Marking the array reference as final doesn't cut it because this is still perfectly legal:
MY_URLS[0] = "es-form.html";
Also, how locked in are you into embedding locale into the url like that in the first place? Are you emulating legacy links? Spring has plenty of built in support for using the browser's actual locale.

Dynamically creating a JSF form with java reflection

I'm trying to create a simple crud form to insert data into a database with hibernate, without knowing what the object type is. The ultimate goal is to only have one insert form for every table in the database. So far i get the methods that the current object has, check to see if it has any set methods and create a text input for every field that has a set.
UIViewRoot viewRoot = FacesContext.getCurrentInstance().getViewRoot();
HtmlPanelGrid hpg = (HtmlPanelGrid) viewRoot.findComponent("panel");
for (Method method : declaredFields) {
String name = method.getName();
if (name.contains("set")) {
HtmlOutputText hot = new HtmlOutputText();
HtmlInputText hit = new HtmlInputText();
hot.setValue(name.substring(3));
try {
hit.setValue(newObject.getClass().getMethod(name, String.class));
} catch (Exception ex) {
Logger.getLogger(ReflectController.class.getName()).log(Level.SEVERE, null, ex);
}
hpg.getChildren().add(hot);
hpg.getChildren().add(hit);
}
}
Here newObject is the object that is going to be inserted into the database later with hibernate. My problem is this:
How do assign a certain field from that object to the text input that is being created at the moment. So far if I put the method in the value like I'm doing above, it will just print out the method in the value attribute for that input. what i want is that when this form is submited, for to assign the value in that text box to the property with that name.

I can give you a partial answer - You need to create a ValueExpression dynamically
Application app = FacesContext.getCurrentInstance().getApplication();
hit.setValueExpression("value", app.getExpressionFactory().createValueExpression(FacesContext.getCurrentInstance().getELContext(), "#{bean.item}", Item.class));
The hard part will be creating the valueExpression that will actually map to a field within your object's value. That requires a great deal more thought but you will for sure need the dynamic valueExpression. As written, this will result in the execution of your bean's setItem();method with a parameter of type Item. You will require something a little more complex.

In JSF, binding input components to properties is accomplished with EL-expressions. You can create one programmatically as Steve shows, but that syntax is really ugly. On a related note, programmatic manipulation of the component tree is a rather unorthodox way of using JSF. The orthodox way to tackle your requirement would be something like:
<ui:repeat var="prop" value="#{genericEditorBean.propertyNames}">
<h:outputLabel value="#{prop}" for="input"/>
<h:inputText id="input" value="#{genericEditorBean.object[prop]}"/>
</ui:repeat>
where
public List<String> getPropertyNames() {
List<String> propertyNames = new ArrayList<>();
BeanInfo beanInfo = Introspector.getBeanInfo(object.getClass());
for (PropertyDescriptor pd : beanInfo.getPropertyDescriptors()) {
propertyNames.add(pd.getName());
}
return propertyNames;
}
(There really is no reason to reimplement scanning for Java Bean properties when the Java API offers a class for that very purpose. Unlike your home-grown version, this will also handle properties inherited from a super class ...)

I once used an open-source library named MetaWidget to do this.
It was a few years ago, but it worked well and was easy to set up.
It looks like the project is still active:
http://metawidget.sourceforge.net/index.php

JSP MVC Model 2 Architecture Question

I want to develop a web application and I have access this API. In the API there are methods that allow you to get the userId of the current user via context objects. Maybe I'm overthinking this, but I'm very confused as to where to put my CurrentUserId() method. Does that method go in the controller or the model? I was thinking it goes in the model, but it seems redundant to write a property called "getUserId" to return a string called getUserId().toString(). Is this normal and I'm overthinking or am I correct? My co-worker told me to put the logic in the view, but from everything I've read you never put java code or scriplets in the view. I hope this makes sense.
Also here's a method I wrote to return the userId as a string
protected String CurrentUserId(HttpServletRequest request)
{
ContextManager ctxMgr = ContextManagerFactory.getInstance();
Context ctx = ctxMgr.setContext(HttpServletRequest request);
Id userID = ctx.getUserId();
return userID.toString();
}

It should go to Controller.
Create a utility class having this method as static
Because here HttpServletRequest is this model specific(jsp,servlet) , suppose tomorrow if you want to apply the same model to your desktop application then it would fail so better place is controller.