對於分組表格，要想獲取到分組的某一個分組

var courseStore=Ext.create('Ext.data.Store',{
		   storeId:'courseStore',
		   fields:['Name','Type','Credit','Period','Teacher'],
		   autoLoad:{start:0,limit:itemsPerPage},
		   pageSize: itemsPerPage,
		   groupField:'Type',
//		   data:{'items':[
//		   	{'Name':'SQL深入詳解','Type':'必修','Credit':'3','Period':'6周','Teacher':'zhang'},
//		   	{'Name':'SQL深入詳解','Type':'必修','Credit':'3','Period':'6周','Teacher':'zhang'},	   	
//		   	]},
		   	proxy:{
			   	  type:'ajax',
			      url:'json/course.json',
			   	  
			   	  reader:{
			   	    type:'json',
			   	    root:'items',
			   	    totalProperty:'counts'
			   	  }
			}
		});
	
	var sm=Ext.create("Ext.selection.CheckboxModel",{
		mode:'MULTI',
		checkOnly:true,
		renderer:function(value,metaData,record,rowIndex,colIndex,store,view){
		    var type=record.get("Type");
		    if(type=="必修"){
		    	return  '';
		    }else{
		    	return '<div class="' + Ext.baseCSSPrefix + 'grid-row-checker"> </div>';
		    }
		    
	    }
	    
	});
	var courseGrid=Ext.create('Ext.grid.Panel',{
	       store:courseStore,
	       selModel:sm,
	       multiSelect:true,
	       viewConfig:{
		       forceFit:true,
		       scrollOffset: 0
	      },
	      features:[
	   	         Ext.create("Ext.grid.feature.Grouping",{
	   	        	 groupHeaderTpl:'課程型別：{name}(共有{rows.length}門)',
	   	        	 startCollapsed:false
	   	         })
	   	                
	   	    ],
	       columns:[
	         {header:'課程名',dataIndex:'Name',flex:2},
	         {header:'型別',dataIndex:'Type'},
	         {header:'學分',dataIndex:'Credit'},
	         {header:'學時',dataIndex:'Period'},
	         {header:'代課老師',dataIndex:'Teacher'},
	       ],
	       listeners:{
	    	  viewready:function(grid,eOpts){
	    	      var hd_checker =grid.getEl().select('.x-column-header-checkbox');
	 	    	  var hd = hd_checker.first();
	 	          if (hd_checker.hasCls('x-column-header-checkbox')) {   
	 	                hd_checker.removeCls('x-column-header-checkbox'); 0// 去掉全選框
	 	          }   
	 	          hd.destroy();
	           }
	    	  
	      }
	       
	});
 

var myStore = Ext.create('Ext.data.Store', {
    groupField: 'color',
    groupDir  : 'DESC'
});

myStore.getGroups(); //returns:
[
    {
        name: 'yellow',
        children: [
            //all records where the color field is 'yellow'
        ]
    },
    {
        name: 'red',
        children: [
            //all records where the color field is 'red'
        ]
    }
]
 

//確認選擇的課
	function selectCourseOk(){
		var mustSelectCount;//必修個數，必須選擇
		var records=courseStore.getGroups("必修").children; //返回是model[]
		mustSelectCount=records.length;
		alert(mustSelectCount);
		courseGrid.getSelectionModel().selectRange(0,mustSelectCount-1,true);
		var recordes=courseGrid.getSelectionModel().getSelecion();  //返回Model[]
		
	}