Blog: Posts from September, 2008

A common requirement in many applications is to display various aggregate values when data is presented in a grid view.

The latest release of Data Aquarium Framework introduces a new feature that does exactly that. Aggregate feature is shown in the following screen shot. See a live demo of this feature.

Columns Required Date, Shipped Date, and Freight are displaying values in the aggregate row at the bottom of the grid view just above the pager. Here is how these data fields are defined in grid1 view of data controller ~/Controllers/Orders.aspx in a sample application.

<view id="grid1" type="Grid" commandId="command1" label="Orders">
  <headerText>This is a list of orders. </headerText>
  <dataFields>
    <dataField fieldName="OrderID"/>
    <dataField fieldName="CustomerID" aliasFieldName="CustomerCompanyName" />
    <dataField fieldName="EmployeeID" aliasFieldName="EmployeeLastName" />
    <dataField fieldName="OrderDate" columns="10"/>
    <dataField fieldName="RequiredDate" columns="10"  aggregate="Max"/>
    <dataField fieldName="ShippedDate" columns="10"  aggregate="Max"/>
    <dataField fieldName="ShipVia" aliasFieldName="ShipViaCompanyName" />
    <dataField fieldName="Freight" dataFormatString="c" columns="15"
      aggregate="Sum"/>
    <dataField fieldName="ShipName" columns="40" />
  </dataFields>
</view>

Attribute aggregate specified an aggregate function that instructs the data controller to calculate aggregates when a total number of records in a data set is being determined.

An SQL statement with corresponding aggregate functions is executed, which provides maximum speed and efficiency. Many commercially available grids will calculate aggregates by scanning the entire record set. Data Aquarium Framework simply relies on speed and power of your database server.

Aggregates automatically take into account any filters that may have been imposed on a data set by users and master-detail links. In this illustration you can see orders filtered by Ship Via and Ship Name. Aggregates were recalculated accordingly.

Custom headers and footers can boost ease of use of your applications created with Data Aquarium Framework.  Take a look at the following screen shot.

Data field Unit Price features custom header and footer. Here is how we have defined this view in ~/Controllers/Products.xml of our sample application.

<view id="editForm1" type="Form" commandId="command1" label="Review Products">
  <headerText>Please review products information below. 
    Click Edit to change this record, click Delete to delete the record, 
    or click Cancel/Close to return back.</headerText>
  <categories>
    <category headerText="Products">
      <description>These are the fields of the products record 
        that can be edited.</description>
      <dataFields>
        <dataField fieldName="ProductName" columns="40" />
        <dataField fieldName="SupplierID" aliasFieldName="SupplierCompanyName" />
        <dataField fieldName="CategoryID" aliasFieldName="CategoryCategoryName" />
        <dataField fieldName="QuantityPerUnit" columns="20" />
        <dataField fieldName="UnitPrice" dataFormatString="c" columns="15">
          <headerText>Price of Unit:</headerText>
          <footerText>
            <![CDATA[ 
            <div style="color:navy">
            Enter price of unit in USD. Make sure to consult catalog of products 
            sold by our competitors at
            <a href="http://www.amazon.com" target="_blank">amazon.com</a>
            </div>]]>
          </footerText>
        </dataField>
        <dataField fieldName="UnitsInStock" columns="15" />
        <dataField fieldName="UnitsOnOrder" columns="15" />
        <dataField fieldName="ReorderLevel" columns="15" />
        <dataField fieldName="Discontinued" />
      </dataFields>
    </category>
  </categories>
</view>

HeaderText is displayed above the field value while the FooterText is displayed just under the field value. By default the field header is inherited from the label attribute of the base field.

You can break down the fields in the standard views in a few categories to further improve the form presentation.

Header and footer text will also automatically display in a custom form. Define the following markup in your web form that displays products.

<aquarium:DataViewExtender ID="ProductsExtender" runat="server" 
    Controller="Products" TargetControlID="ProductList" />
<div id="Products_editForm1" style="display: none">
    {ProductName}<br />
    {SupplierID}<br />
    {CategoryID}<br />
    {UnitPrice}
</div>

This simple markup will alter the form view presentation shown in the screen shot above to look like the one below.

Custom form templates allow ad hoc form view presentation when standard layout does not provide enough flexibility.