XMLList, HierarchicalData and AdvancedDataGrid

Using a XMLList as source for GroupingCollection or HierarchicalData is a bit tricky. The trickiness comes from the fact that there are two ways to specify values for a XML node. One as attributes and second as child nodes. Depending on which way values are specified we need to set properties differently to get the desired display in ADG. For XMLList data type HierarchicalData treats the child nodes of a node to be children of the parent node by default. Specifying values as attributes:

<Parent field1="valueA" field2="valueB" >
 <Child1 field1="value1" field2="value1b" />
 <Child2 field1="value2" field2="value2b" />
 <Child3 field1="value3" field2="value3b" />
</Parent>

Here Child1, Child2 and Child3 would be recognized as children of Parent node. Specifying values as sub nodes:

<Parent>
    <field1>valueA</field1>
    <field2>valueB</field2>

   <subnodes>
    <Child1>
     <field1>value1</field1>
     <field2>value1b</field2>
    </Child1>
    <Child2>
     <field1>value2</field1>
     <field2>value2b</field2>
    </Child2>
    <Child3>
     <field1>value3</field1>
     <field2>value3b</field2>
    </Child3>
   </subnodes>
</Parent>

If above data is set as source to HierarchicalData it would treat field1, field2 and subnodes as children of Parent node, which is not correct. To tell HierarchicalData to use only the nodes under subnodes as children set HierarchicalData.childrenField to "subnodes".

The same rules apply when GroupingCollection (which is derived from HierarchicalData) is used to group flat data.

Suppose following data is used as input to GroupingCollection and grouped on Region

<Row>
    <Region>Southwest</Region>
    <Territory>Arizona</Territory>
    <Territory_Rep>Barbara Jennings</Territory_Rep>
    <Actual>38865</Actual>
    <Estimate>40000</Estimate>
</Row>

<Row>
    <Region>Southwest</Region>
    <Territory>trials</Territory>
    <Territory_Rep>Dana Binn</Territory_Rep>
    <Actual>4000</Actual>
    <Estimate>5000</Estimate>
</Row>
 
<Row>
    <Region>SouthEast</Region>
    <Territory>Central California</Territory>
    <Territory_Rep>Joe Smith</Territory_Rep>
    <Actual>5000</Actual>
    <Estimate>6000</Estimate>
</Row>

<Row>
   <Region>Southwest</Region>
   <Territory>Nevada</Territory>
   <Territory_Rep>Bethany Pittman</Territory_Rep>
   <Actual>1000</Actual>
   <Estimate>2000</Estimate>
</Row>

The result won't get displayed because the base HierarchicalData would treat <Region>, <Territory> etc nodes also as children of Row. To get proper display we need to set GroupingCollection.childrenField="abc" or some non existent node name. This would cause HierarchicalData to report that no children exist for the Row.

Smart column width based on data displayed (Part One: No code yet)

From the poll conducted I find that many users want Smart column width based on data displayed in DG/ADG.

I hope people requesting this feature know that it is a CPU intensive process to go over all the items in the dataProvider to find out maximum width required for all the columns. If the number of visible columns is more it would take even more time to compute the values and layout the columns.

If a labelFunction is being used at DG or DGColumn level and custom styles have been used on a column for fontSize for example, it complicates the computation even more.

When the data is being paged from a server it is not possible to compute the smart width at all without requesting all the data from the server, which is never desirable.

Keeping these things in mind I feel it makes sense to have a flag on individaul DGcolumn (apart from one on the DG itself) to control the computation of smart width. If the flag is true width is computed and false would use the normal way of determining the column width.

Thoughts?

Generating summary for flat data using GroupingCollection

This example shows how GroupingCollection can be used to generate summary data for flat data and AdvancedDataGrid can be used to display the result.

The trick (or dirty work around if you like to call it so) is to generate a single dummy group using a invalid grouping field. The summary we require is specified as usual using the SummaryRow and SummaryField.

When this GroupingCollection is fed to ADG.dataProvider it would try to display in a tree view. By setting the HierarchicalCollectionView.showRoot flag to false to avoid displaying the single group parent.

By specifying the default ADGItemRenderer as ADG.groupItemRenderer we can prevent the group icons from getting displayed.

The source is here.

Please note I have not tested this example extensively. So some bug fixes may be required before it can be used in production.

Customizing Group label fields when using GroupingCollection

By using the ADG.groupLabelFunction property one can customize the group label displayed for the group nodes. The following example shows how children count can be displayed as part of the group label when the group is closed. The source can be found here.

Poll for current and new features in AdvancedDataGrid

I created three polls at the end of my blog. One to know how users are feelling about ADG in its current form, second what features of ADG in Flex 3 users are liking the most and third one to see what new features users would like to see in the next version of AdvancedDataGrid to make it more useful.

Who knows you may be able to guide the future developement of ADG !

Thanks in advance for giving your opinion!

If you want to see more choices do leave a comment. I would add it.

Async refresh of GroupingCollection

In Flex 3 Beta-2, GroupingCollection adds support for asychronous refresh. When we have large number of input rows or don't want to wait for the grouping to finish to see the results we can pass true to GroupingCollection.refresh(async:Boolean) and get to view the results as the grouped data is built. Users are allowed to interact with the shown information. Refresh can be even stopped by calling cancelRefresh.

I wrote a small app to test this. The app generates random data and displays it in AdvancedDataGrid(ADG) when "Populate ADG" is clicked. The number of data rows can be modified using the numeric stepper. A click on "Group" starts async refresh and ADG starts displaying the results immediately. Grouping can be cancelled any time using "Cancel Grouping". The three check boxes allow different combinations of grouping to be performed.

Option to pause/resume a refresh is not available.

The source is available here.

Displaying charts in AdvancedDataGrid

Using charts as itemRenderers in DG and ADG is easy. Find the sample files here The sample uses a LineChart as itemRenderer for the third column and a PieChart in the child area. The column-spanning option available through RendererProviders is used to make the PieChart occupy the whole row. The sample shows use of HierarchicalData but even without that All chart types can be used as itemRenderes.