Documentation for GXT Data Binding

[robnauticus]

Hello I am eager to test out and possibly implement the Data Binding feature of the Designer 7.5.

I am unable to find any specific docs on the subject. I took a look at the Swing version of data binding but the translation from Swing to GXT is not 100% clear to me.

Any help would be great!
Wonderful product,
Rob

[Eric Clayberg]

We will be adding some docs for that soon.

In the mean time, you should refer to the GXT site for info about how to use their Data Binding API.

I have attached a GXT Data Binding example that you can start with. Note that the file does not include the GXT jars (to keep the file size smaller), so you will need to add those to the project yourself.

[robnauticus]

Thank you Eric! I will get cracking...

Maybe the impedance I am getting is from using BeanModel. I am wrapping my POJO's in a BeanModelMarker.

[Eric Clayberg]

We support BeanModel.

AFAIK, GXT bindings (Bindings, FormBinding, FieldBinding) only work with BeanModel.

[Eric Clayberg]

I have attached a more detailed GXT Data Binding example illustrating both basic bindings and grid bindings.

Note that the file does not include the GXT jars (to keep the file size smaller), so you will need to add those to the project yourself.

[NecroSado]

We support BeanModel.

AFAIK, GXT bindings (Bindings, FormBinding, FieldBinding) only work with BeanModel.

Hi,

binding seems to work with ModelData, which is the BeanModel interface.
It is possible to implement the interface on our home-made beans to link the overridens get() and set() method so they call our own accessors without storing datas in a map.

However, i don't find a way to use the Databinding screen to bind my data if i don't use BeanModel.
Is there a way to do so?

[Eric Clayberg]

You would need to do this manually. We only plan to support BeanModel subclasses.

[NecroSado]

This is not really the java philosophy... you should always use the interface for loose coupling.
In the BeanModel javadoc, it says it's the default implementation of ModelData.
I never seen a tool only supporting the default implementation of a functionality.

Are you using reflexion/introspection to find out the BeanModel's property? Knowing that could help us to "mock" the BeanModel and wrap our POJO so their property finally appears.

[Eric Clayberg]

We support ModelData only in "autoBind" mode. This requires that each field on a form must have a 'name' property corresponding to the bean property with same name. For custom field-to-property binding we can only support beans based on BaseModel. This is due to the fact that in the general case we can not get a property list for arbitrary ModelData (we are not creating bean instances). For a BaseModel we visit its compilation unit (if available) for collecting its property list. In BaseModel compilation units we are using various invocations of com.extjs.gxt.ui.client.data.BaseModel.set(String, <T>) to gather information about the existing bean properties (the existence of these invocations is guaranteed by BaseModel but not guaranteed by ModelData).

Once the core WindowBuilder engine is open sourced through Eclipse.org, we would expect the GXT vendor to take over support and development for any GXT-related extensions to GWT Designer (as would be the case for any 3rd party library vendor). If they wish to enhance the GXT data binding support to handle ModelData, we would be happy to point them in the right direction.

[NecroSado]

Thanks for the explanation.
With these infos, i've finally been able to bind our home-made POJO with the binding screen, displaying our properties.
For future usage, i'll soon post an example of well formed implementation of ModelData that shows the properties in the screen.

[Eric Clayberg]

Sounds good.

[NecroSado]

Here's an example of a ModelData working with the binding screen.
It's based on modeldata projet's (http://code.google.com/p/unitt/wiki/modeldata) output, but using the for loop in getProperties() makes the binding screen not working.

Code: Select all

import java.util.ArrayList;
import java.util.Collection;
import java.util.HashMap;
import java.util.Map;

import com.extjs.gxt.ui.client.data.ModelData;

public class POJO implements ModelData{

   /**
    * POJO Attributes
    */
   private String strProp;
   private Integer intProp;
   
   /**
    * POJO Accessors
    * @param strProp
    */
   
   public void setStrProp(String strProp) {
      this.strProp = strProp;
   }

   public String getStrProp() {
      return strProp;
   }

   public void setIntProp(Integer intProp) {
      this.intProp = intProp;
   }

   public Integer getIntProp() {
      return intProp;
   }

   
   /**
    * ModelData Implementation
    */
   
   @Override
   public <X> X get(String property) {
      
      if("strProp".equals(property)){
         return (X)getStrProp();
      }else if("intProp".equals(property)){
         return (X)getIntProp();
      }
      
      return null;
   }

   @Override
   public Map<String, Object> getProperties() {
      Map<String, Object> toReturn = new HashMap<String, Object>();
      
      //Working
      toReturn.put("strProp", get("strProp"));
      toReturn.put("intProp", get("intProp"));
      
      /*
      Not working
      
      for (String property : getPropertyNames())
        {
         toReturn.put(property, get(property));
        }
        */
      return toReturn;
   }

   @Override
   public Collection<String> getPropertyNames() {
      Collection<String> toReturn = new ArrayList<String>();
      toReturn.add("strProp");
      toReturn.add("intProp");
      return toReturn;
   }

   @Override
   public <X> X remove(String property) {
      return set(property, null);
   }

   @Override
   public <X> X set(String property, X value) {
      X toReturn = get(property);
      
      if("strProp".equals(property)){
         setStrProp((String)value);
      }else if("intProp".equals(property)){
         setIntProp((Integer)value);
      }
      
      return toReturn;
   }

}


[Eric Clayberg]

Thanks for the example.