how to get id of selected item value from selectOneMenu in jsf? - jsf-2

Question

I have dropdown of categories. On selecting particular category, I have rendered another dropdown of subcategories of that category. I want id of selected subcategory.But I am not getting it.My code is:
<tr>
<td align="right">
<h:outputText value="Select Main Category:"></h:outputText>
</td>
<td>
<h:selectOneMenu id="cmbcategory" value="#{categoryBean.categoryID}" required="true" requiredMessage="Select Category" >
<f:selectItem itemLabel="--Select Category--" itemValue="0"></f:selectItem>
<f:selectItems value="#{categoryBean.categories}" var="item" itemLabel="#{item.categoryName}" itemValue="#{item.categoryID}"></f:selectItems>
<f:ajax event="valueChange" render="cmbsubcategory" immediate="true" listener="#{categoryBean.SubcategoriesByCategory()}"/>
</h:selectOneMenu>
</td>
<td><h:message for="cmbcategory"></h:message></td>
</tr>
<tr>
<td align="right">
<h:outputText value="Select Sucategory:"></h:outputText>
</td>
<td>
<h:selectOneMenu id="cmbsubcategory" value="#{categoryBean.subCategoryID}" required="true" requiredMessage="Select Subcategory">
<f:selectItem itemLabel="--Select Subcategory--" itemValue="0"></f:selectItem>
<f:selectItems value="#{categoryBean.SubcategoriesByCategory()}" var="item" itemLabel="#{item.subcategoryID}" itemValue="#{item.subcategoryID}"></f:selectItems>
</h:selectOneMenu>
</td>
<td><h:message for="cmbsubcategory"></h:message></td>
</tr>
And my bean is:
public int getCategoryID() {
return CategoryID;
}
public void setCategoryID(int CategoryID) {
this.CategoryID = CategoryID;
}
public String getCategoryName() {
return CategoryName;
}
public void setCategoryName(String CategoryName) {
this.CategoryName = CategoryName;
}
public Collection<Category> getCategories() {
categories=abr.getAllCategory();
return categories;
}
public Collection<Subcategory> SubcategoriesByCategory()
{
System.out.print("catid...... "+CategoryID);
subcats= abr.searchAllSubcategoriesByCategory(CategoryID);
return subcats;
// +"size....."+ subcats.size());
}
public String getSubCatName() {
return SubCatName;
}
public void setSubCatName(String SubCatName) {
this.SubCatName = SubCatName;
}
public int getSubCategoryID() {
System.out.print("subcatid...... "+SubCategoryID);
return SubCategoryID;
}
public void setSubCategoryID(int SubCategoryID) {
this.SubCategoryID = SubCategoryID;
}
public Collection<Subcategory> getSubcats() {
return subcats;
}
public void setSubcats(Collection<Subcategory> subcats) {
this.subcats = subcats;
}
public void setCategories(Collection<Category> categories) {
this.categories = categories;
}

Answer 1

You are mixing up a property getter with an action method. A getter should return the property and an action method should be void or return a String.
Change
public Collection<Subcategory> SubcategoriesByCategory() {
..
}
to
public void searchSubcats() {
subcats= abr.searchAllSubcategoriesByCategory(CategoryID);
}
and call this method in your ajax request:
<f:ajax .. listener="#{categoryBean.searchSubcats}"/>
The selectItems in the second drow-down then need to reference the getter for subcats:
<f:selectItems value="#{categoryBean.subcats}" ... />