I am trying to use NetBeans to bind a JTextField to the selected element of a JTable.
The JTable gets its data from an AbstractTableModel subclass which returns Cow objects. At present, each Cow object is displayed as a String through its toString method.
I am trying to bind the text property of the JTextField to the name property of the Cow object which is selected in the JTable.
I bound the text property of the JTextField in NetBeans to:
flowTable[${selectedElement.name}]
This produces the following line of generated code:
org.jdesktop.beansbinding.Binding binding =
org.jdesktop.beansbinding.Bindings.createAutoBinding(
org.jdesktop.beansbinding.AutoBinding.UpdateStrategy.READ_WRITE,
cowTable,
org.jdesktop.beansbinding.ELProperty.create("${selectedElement.name}"),
cowNameTextField,
org.jdesktop.beansbinding.BeanProperty.create("text"));
The bound value of the text field is always null.
What am I doing wrong?
Does your Cow class have a public String getName() method returning the name?
If it doesn't, the outcome you're getting would be expected. If it does, could you post more code (your data class, tablemodel, table...).
If you only are interested in a String in the table, and not the Cow object itself:
table.getSelectionModel().addListSelectionListener(new ListSelectionListener() {
#Override
public void valueChanged(ListSelectionEvent e) {
if(!e.getValueIsAdjusting()) {
Object value = table.getValueAt(e.getFirstIndex(), COLUMN_X);
jTextField.setText(value.toString());
}
}
);
Does your Cow class support adding a PropertyChangeListener? I did not use the beans binding support from NetBeans that often, but I remember you needed it. Anyway, a little more code could help with finding out whats going wrong.
Related
I'm writing a JFace dialog, and I'd like to use databing to a model object.
Looking at code I can see that there are times when I find a PojoProperties used to build the binding, while other time it is used a PojoObservables.
Looking at the Javadoc I can read:
PojoObservables: A factory for creating observable objects for POJOs (plain old java objects) that conform to idea of an object with getters and setters but does not provide property change events on change.
PojoProperties: A factory for creating properties for POJOs (plain old Java objects) that conform to idea of an object with getters and setters but does not provide property change events on change.
The same question applies to the difference that exists between BeansObservables and BeansProperties
The (obvious) difference sems to be that the observable allows to observe objects and the properties allows to observe properties, but since a Pojo has a getter and a setter for its data, what is the difference between them? And which of them should I choose for my dialog?
Here follows a code excerpt:
The POJO:
public class DataObject {
private String m_value;
public String getValue() {
return m_value;
}
public void setValue(String i_value) {
m_value = i_value;
}
}
The DIALOG (relevant part):
#Override
protected Control createDialogArea(Composite parent) {
Composite container = (Composite) super.createDialogArea(parent);
m_combo = new Combo(container, SWT.BORDER);
m_comboViewer = new ComboViewer(container, SWT.NONE);
}
The BINDING (relevant part):
// using PojoObservable
IObservableValue observeValue = PojoObservables.observeValue(m_dataObject, "value");
IObservableValue observeWidget = SWTObservables.observeSelection(m_combo);
// using PojoProperties
IObservableValue observeValue = PojoProperties.value("value").observe(m_dataObject);
IObservableValue observeWidget = ViewerProperties.singleSelection().observe(m_comboViewer);
I understand that one time I'm using a combo and another I'm using a ComboViewer, but I can get the combo from the viewer and bind the other way if I need...
Also, can I mix the two, for example use the observeValue with the ViewerProperties?
IObservableValue observeValue = PojoObservables.observeValue(m_dataObject, "value");
IObservableValue observeWidget = ViewerProperties.singleSelection().observe(m_comboViewer);
I am playing around a little with JFace viewers (especially ComboViewer) & databinding and discovered that if I use
SWTObservables.observeSelection(comboViewer.getCombo());
then databinding is not working correctly.
However, if I use
ViewersObservables.observeSingleSelection(comboViewer);
Then everything is working as expected.
Maybe this is a special for my case, so to get it a better overview I'll describe my set up in following paragraph.
I have modelObject with field named selectedEntity and entities and bind this ComboViewer to the modelObject.
I want to display all "entities" in model object, if I add any entity to the modelObject.entities collection then I want to this entity be added to combo automatically.
If user selects some item in combo I want to modelObject.selectedEntity be set automatically.
If I set modelObject.selectedEntity I want to combo selection be set automatically.
Source code can be found at: https://gist.github.com/3938502
Since Eclipse Mars, PojoObservables is deprecated in favor of PojoProperties and BeansObservables is deprecated in favor of BeanProperties so the answer to which one should be used has now become evident.
I've got a bindable model class (lets call it myModel) with two properties, label and value. The value gets updated frequently, so it is marked as bindable.
Works fine so far, the data is updated and the standard property change event is dispatched.
Now I have to make an ArrayCollection from the object instances of this model to use it as a data provider in a data group. The data gets then passed to a custom itemRenderer in which I access the myModel properties via data.label and data.value.
The only problem I've got now is that the myModel value property doesn't change any more (I suppose because I stored the objects in the ArrayCollection).
The ArrayCollection is marked bindable as well btw, because new object instances of myModel can be added during runtime.
Is there any way to make this work? Any help regarding this would be much appreciated!
Edit: I almost forgot, the value object in the myModel class is updated by another bindable class. Yes, I know that's bonkers but that's why I'm here, to get some input on a simpler (and in fact working) way to solve this problem.
2nd edit: Allright guys, a little bit of code to illustrate the issue;
Lets start with the first bindable class;
[Bindable]
public class FirstClass
{
public var name:String;
public var firstValue:Number;
public var secondValue:Number;
public var thirdValue:Number;
public function FirstClass()
{ }
}
The values (first to third) get updated by a controller class. So far so good.
Now to the second model class (for matters of consistency, lets keep the MyClass name)
[Bindable]
public class MyClass
{
public var label:String;
public var value:Number;
public function FirstClass()
{ }
}
These are the two model classes. Background behind this is that I need a String value (a label) for each property of an instance of FirstClass. I'd like to make this simpler, so I'm really not settled on this "solution" cough ;).
Anyhow, we've got the two models, now to my .mxml class;
[Bindable] private var firstClassInstance:FirstClass;
I create a new ArrayCollection and add objects like this;
myArrayCollection.addItem(new MyClass("This is a label", firstClassInstance.firstValue));
And again, the DataGroup uses this ArrayCollection as a data provider.
As we already established (thank you #Windowns), the ArrayCollection looks only for objects being added or removed, not property changes of these objects.
Call itemUpdated on your ArrayCollection when you update a "piece" of an item stored in it.
There could be many issues with binding. Please post code to help us see what is happening. Here are some "high level" things to watch out for that might answer your question
When using an bindable arraycollection of objects, it's important to note that the binding for the arraycollection only looks at each object instance and if it's added or removed from the collection. It will not know about any property changes that occur to your object. Commonly when you use an itemrenderer, the properties are bound to display elements. Like maybe the "value" property bound to a label in the itemrenderer. Now when your object instance (myModel) changes it's "value" property the label should pick it up. Also note that you need to mark any properties you intend to bind to visual elements with the [Bindable] meta-tag.
public class myModel
{
[Bindable]
public var label:String;
[Bindable]
public var value:String;
public function myModel() {}
}
Answer after code post:
When you do the following:
myArrayCollection.addItem(new MyClass("This is a label", firstClassInstance.firstValue));
You are taking the value of firstClassInstance.firstValue and supplying it as a hard value (as in not passing value by reference). So if you do the following:
myArrayCollection.getItemAt(addedClassIndex).value = 5;
Will not cause any changes to be noted in the firstClassInstance.firstValue as there is no "referening information" stored. We are only working with the basic type of Number which is never passed by reference like all other objects are in Flex.
Maybe try this:
[Bindable]
public class MyClass
{
public var label:String;
[Bindable] //might be redundant due to global [Bindable] flag, been a while since i've used a global one
public function get value():Number{
return m_objRef.firstValue;
}
public function set value(value:Number):void{
m_objRef.firstValue = value;
}
private var m_objRef:FirstClass;
public function MyClass(_label:String, _valueObj:FirstClass) {
m_objRef = _valueObj;
label = _label;
}
}
Allright guys (and gals ;)) after two hours of messing around with BindingUtils, I finally found the solution to my problem.
The two model classes can remain the way they are, so passing the instance of FirstClass isn't necessary.
Simply binding the value properties of FirstClass to the value field of MyClass works as expected and the values in the ArrayCollection get updated as well.
So the solution;
myClassObject = new MyClass();
myClassObject.label = "This is a label";
BindingUtils.bindProperty(myClassObject, "value", firstClassObject, "firstValue");
And then simply add the myClassObject to the ArrayCollection.
Keep in mind that all the code here is pseudo code, so never mind any typos.
Still, #Windowns suggesting with passing the FirstClass object to the MyClass will be incorporated into my final solution as it makes switching between properties a lot easier (FirstClass has got lots of them, not just the 4 in my first post). Many thanks for that!
I took Amy's advice and researched a little further on the itemUpdated method. Turns out, the solution was right there.
See here: http://flex4examples.wordpress.com/2009/08/28/1st/
I applied this methodology (with little variations) to my code and it works quite good. Performance on the iPad2 is good and so is the memory usage of my component.
Let's hope that Amy is fine with this solution as well. Fingers crossed. ;)
I have two classes in two separate libraries (one VB, one C#):
Public Class Item
...
Public Overridable ReadOnly Property TotalPrice() As String
Get
Return FormatCurrency(Price + SelectedOptionsTotal())
End Get
End Property
End Class
and
public class DerivedItem : Item {
...
public new Decimal TotalPrice
{
get { return Price + OptionsPrice; }
}
}
As you can see, the DerivedItem.TotalPrice shadows the Item.TotalPrice property. However, when trying to retrieve the DerivedItem.TotalPrice value, I'm still getting the base object's TotalPrice value.
Why is the DerivedItem's property not being returned?
EDIT
I've actually found the problem! I am getting the wrong value in the JSON string being returned via AJAX. It turns out that the TotalPrice is being returned correctly, it's just being overwritten by the shadowed property call being made later in the JSON string. My new question, then, is how to I prevent the shadowed property from being serialized?
(This question has been rescoped here)
It may depend on how you are instantiating the object.
For example:
DerivedItem i = new DerivedItem();
i.TotalPrice();
Will call the shadowed version.
However:
Item i = new DerivedItem();
i.TotalPrice();
Will actually call the base.
Here's a nice explanation.
Of course if at all possible I would avoid shadowing.... :-)
Are you referecing TotalPrice from a reference to the base type?
Item item = new DerivedItem;
string s = item.TotalPrice;
Does setting <NonSerialized()> attribute on the base class property work?
Using Asp.net's Bind() method, how do I bind to the object itself, not one of it's properties?
I think what Ryan means here like if you have to an object like this
public class Person
{
public string FirstName { get; set; }
public string LastName { get; set; }
}
And if you bind Person object to anywhere in GridView or Repeater to any DataSource you only bind Person and it get a default bind value from one of its properties.
support we have a variable Ryan from Person type so i want to get the variable value from calling <%# Eval("Ryan") %> not <%# Eval("Ryan.FirstName") %>
I tried to put an attribute DefaultBindingProperty for the class but it's not working
[System.ComponentModel.DefaultBindingProperty("FirstName")]
public class Person
{
public string FirstName { get; set; }
public string LastName { get; set; }
}
So does any one knows how to do it properly?
I ended up working around this by adding a property called SelfReference that simply returns this. If anyone reads this and has a better solution, I'd like to hear it.
You may use Container.DataItem instead:
Item='<%# Container.DataItem %>'
I'm not sure to what exactly you want to bind. The only thing that would make sense to me at the moment is to bind to some UI control, say a DropDown control for instance.
There usually some text properties for the value being displayed and value properties for the actual value to function as identifier. On the Dropdown
DataTextField
DataValueField
There you specify DataTextField = "Firstname" and DataValueField = "Id" given that you have an object that has properties "Firstname" and "Id".
On lists you can use the Eval function directly on your ASPX code or you add server-side controls (i.e. Literals, Labels) inside the list templates and implement the ItemDataBound event (taking the Repeater as example). Here's a good example which illustrates this further.
Hope I was able to help a little ;)
I figured out a way somehow. Actually it is in "http://msdn.microsoft.com/en-us/library/ms752347.aspx"
ListBox ItemsSource="{**Binding**}" IsSynchronizedWithCurrentItem="true"/>
Note that although we have emphasized that the Path to the value to use is one of the four necessary components of a binding, in the scenarios which you want to bind to an entire object, the value to use would be the same as the binding source object. In those cases, it is applicable to not specify a Path. Consider the following example:
XAML
Copy
I have a question regarding a data binding(of multiple properties) for custom DataGridViewColumn.
Here is a schema of what controls that I have, and I need to make it bindable with DataGridView datasource. Any ideas or a link to an article discussing the matter?
Controls
Graph Control(custom): Displayed in
the custrom DataGridView column. Has
properties like "Start Date",
"EndDate", Windows Chart control,
which is itself, bindable, etc.
Custom cell(DataGridViewCustomCell inherits
from DataGridViewCell) that holds
the Graph control and processes some
events(OnEnter event, for example,
passes the focus to the custom Graph
column for drag-n-drop type of
events, etc.)
Custom column(DataGridViewCustomColumn
inherits from DataGridViewColumn)
that defined the cell template type:
CellTemplate = new
DataGridViewCustomCell(); and also a
primary choice for data binding
Data Structure:
Main table to be displayed in other DataGridView Columns
Graph table - related to the Main table via parent-child relationship. Holds graph data
Chart table related to the graph table via parent-child relationship. Holds data for the win-form chart, which is a part of my Graph control.
So far I cannot even bind data from the Graph table to by Graph control or Graph-holding Column/Cell.
Thank you for your answer. My data sources is not a SQL data source, and as a matter of fact I was talking about datagridview for win-forms(I'm not sure that was clear).
As I did not get the reply on any of the forums I was asking the question, I figured, I would outline a solution I came up with, for those who may have a similar problem and for possible critique. :-)
(steps 1-2 are also explained in the famous MS example)
1. Create your own classes that inherit from DataGridViewColumn and DataGridViewCell, setup the column template;
2. Create your "CustomEdit" control
In the data item, whatever that is, a DataRow, or a List item, add a read-only property, that return the object itself. This property is bound to the custom column.
Custom Cell:
public partial class MyCell : DataGridViewCell
{
protected override void Paint(...)
{...} // draws control
// receives data item as a value
// in my case I have to custom-draw entire control in this fnc.
public override void InitializeEditingControl(...)
{...} // initialize control editing
// override some other properties
public override Type EditType {
get{
return typeof(MyEditControl);
}
}
public override Type ValueType{
get{
return typeof(MyItem);
}
}
}
Custom Column:
public partial class MyColumn : DataGridViewColumn
{
public MyColumn(){ ...
CellTemplate = new MyCell();
}
}
Edit Control:
public partial class MyEditControl : UserControl, IDataGridViewEditingControl
{... // implements IDataGridViewEditingControl
// value is our data item
}
Data Item, the data sources becomes List<MyItem>
public class MyItem:Object{
...
[XmlIgnore] // I need it because I do serialization
public MyItem Self {
get {
return this;
}
}
}
See my question Here
It's easy to do, you just don't use the IDE to do it, you do it all in code. It's a lot of work, but it's not that difficult if you know what your doing. I went from knowing nothing to being able to do it in less than a day so I'm sure you'll be able to do it.
Edit: you can also use a Join in the sql that populates the datagridview