Is this a good approache?

[Lippo]

Hi everybody,

could you please have a look at my code and let me know if I'm following the
right path. I think the idea is pretty good but I'm not sure if this is also
good for a big web application.

The idea is the following:
If the user selects a menu entry to view a grid, I first get the data structure
of the grid and after that I actually create a new DataSource which is used
for the grid.

Are there other / better ways to do something like that?

I'm greatful for every advice.

Thanks
Phillip aka Lippo

package de.first.client.Grids;

import java.util.HashMap;

import com.google.gwt.event.shared.HasHandlers;
import com.smartgwt.client.data.DSCallback;
import com.smartgwt.client.data.DSRequest;
import com.smartgwt.client.data.DSResponse;
import com.smartgwt.client.data.RestDataSource;
import com.smartgwt.client.widgets.Canvas;
import com.smartgwt.client.widgets.IButton;
import com.smartgwt.client.widgets.events.ClickEvent;
import com.smartgwt.client.widgets.events.ClickHandler;
import com.smartgwt.client.widgets.grid.ListGrid;
import com.smartgwt.client.widgets.grid.events.CellDoubleClickEvent;
import com.smartgwt.client.widgets.grid.events.CellDoubleClickHandler;

import de.first.client.SelectedData;
import de.first.client.DocFlow;
import de.first.client.PanelFactory;
import de.first.client.WorkPanel;
import de.first.client.data.DynamicDataSource;
import de.first.client.forms.SysUserEdit;

public class SystemGroupGrid extends WorkPanel implements HasHandlers {
	
	HashMap<Integer, SelectedData> ht = new HashMap<Integer, SelectedData>();
	ListGrid sysGroupGrid;
	private RestDataSource restDS;
	Canvas topCanvas = new Canvas();
	//Canvas canvas = new Canvas();
		
	public static class Factory implements PanelFactory {
        private String id;

        public Canvas create() {
        	final SystemGroupGrid panel = new SystemGroupGrid();
            id = panel.getID();
            
            return panel;
        }

        public String getID() {
            return id;
        }

        public String getDescription() {
            return "";
        }
    }
	
	public Canvas getViewPanel() {
		
		Canvas canvas = new Canvas();
		

		// ====================================================================
		// Get grid structure by first REST request
		// ====================================================================
		RestDataSource dataStructureDS;
		dataStructureDS = new RestDataSource();
		dataStructureDS.setDataURL("data/dataIntegration/xml/responses/SysUser_rest.php");
		
		HashMap<String, String> params = new HashMap<String, String>();
		params.put("_tablename", "GridLayout");
		params.put("_sourcetable", "SysGroups");
		DSRequest dsrequest = new DSRequest();
		dsrequest.setParams(params);
		dataStructureDS.setRequestProperties(dsrequest);
		
		// ====================================================================
		// Start request
		// ====================================================================
		dataStructureDS.fetchData(null, new DSCallback(){
			// ====================================================================
			// Wait for response
			// ====================================================================
			public void execute(DSResponse response, Object rawData, DSRequest request) {
			
				// ====================================================================
				// Create structure for the grid
				// ====================================================================
				restDS = new RestDataSource();
				restDS.setDataURL("data/dataIntegration/xml/responses/SysUser_rest.php");
				HashMap<String, String> params = new HashMap<String, String>();
				params.put("_tablename", "SysGroups");
				DSRequest dsrequest = new DSRequest();
				dsrequest.setParams(params);
				restDS.setRequestProperties(dsrequest);
				restDS.setFields(DynamicDataSource.createDataSource(response, new RestDataSource()).getFields());
				System.out.println("Fields have been set.");
				
				sysGroupGrid.setCanEdit(true);
				sysGroupGrid.setWidth(500);  
				sysGroupGrid.setPadding(10);
				sysGroupGrid.setHeight(300);
				sysGroupGrid.setShowFilterEditor(true);  
				sysGroupGrid.setFilterOnKeypress(false);  
				sysGroupGrid.setDataSource(restDS);
				//sysGroupGrid.setAutoFetchData(true); 
				//sysUserGrid.setLoadDataOnDemand(true);
				//sysUserGrid.setCanEdit(true);
				//sysUserGrid.setShowAllRecords(true);
				//sysUserGrid.setShowHeader(false);
				sysGroupGrid.setAutoSaveEdits(true);
				sysGroupGrid.setBorder("0px");
				sysGroupGrid.setLoadingDataMessage("Loading Data");
				sysGroupGrid.setEmptyMessage("No Groups have been found.");
				sysGroupGrid.fetchData();
				
				sysGroupGrid.addCellDoubleClickHandler(new CellDoubleClickHandler(){

					public void onCellDoubleClick(CellDoubleClickEvent event) {
						
						SelectedData s = new SelectedData(event.getRecord().getAttribute("login"), event.getRecord().getAttribute("id"), event.getRecord().getAttribute("login"), "silk/user.png", new SysUserEdit.Factory());
						
						if (ht.containsKey(Integer.valueOf( event.getRecord().getAttribute("id") ).intValue())) {
							DocFlow.showSelectedDataPanel(ht.get(Integer.valueOf( event.getRecord().getAttribute("id") ).intValue()));
						} else {
							ht.put(Integer.valueOf( event.getRecord().getAttribute("id")), s);
							DocFlow.showSelectedDataPanel(ht.get(Integer.valueOf( event.getRecord().getAttribute("id") ).intValue()));
						}
					}
					
				});
			}
		});
		
		
		sysGroupGrid = new ListGrid();
		sysGroupGrid.setCanEdit(true);
		sysGroupGrid.setWidth(500);  
		sysGroupGrid.setPadding(10);
		sysGroupGrid.setHeight(300);
		sysGroupGrid.setBorder("0px");
		sysGroupGrid.setLoadingDataMessage("Loading Data");
		sysGroupGrid.setEmptyMessage("No Groups have been found.");

		IButton editButton = new IButton("New");  
		editButton.setTop(350);  
		editButton.addClickHandler(new ClickHandler() {  
			public void onClick(ClickEvent event) {  
				sysGroupGrid.startEditingNew();  
            }  
		});
		
		IButton saveButton = new IButton("Save");  
		saveButton.setTop(350);  
		saveButton.setLeft(110);  
		saveButton.addClickHandler(new ClickHandler() {  
			public void onClick(ClickEvent event) {  
				sysGroupGrid.saveAllEdits();  
			}  
		});
		
		IButton discardButton = new IButton("Reset");  
		discardButton.setTop(350);  
		discardButton.setLeft(220);  
		discardButton.addClickHandler(new ClickHandler() {  
			public void onClick(ClickEvent event) {  
				sysGroupGrid.discardAllEdits();  
			}  
		});  
		
		canvas.addChild(sysGroupGrid);
		canvas.addChild(editButton);
		canvas.addChild(saveButton); 
		canvas.addChild(discardButton);

		return canvas;
	}
	 
}

[Lippo]

Did I ask for something stupid?
Do you want me to explain some more, what I want to do.
If you need any more information, just let me know.

Best regards
Lippo