Dynamically Formatting Data in Views

How to format the data in a view at runtime.

About this technique	Details
Category	Java Client Techniques> Java-based views
Description	You'll learn about: Adding a data control to a form and setting a column name to use the AgiRowCursor Bandname property Defining column formats for a band format Adding band formats to a view format Initializing a view with dynamic data and a view format
	You can run this technique code from: Database: Examples3_Java Form: frmViewFormatSample NOTE   First make sure that database is running on your localhost SilverStream Server
Related reading	See the chapter on using Java-based views in the Programmer's Guide

In this example, the view displays data from a database table. The view defines two band formats. The value of the data in a particular column determines which band format is used to display the data. All products with a unit price greater than $500 appears red and bold--the format definition of band 2. (See the dataProductAgcData control properties for further details.)

Adding a data control to a form   

In this example, the data is stored in a table named products. This table is located in Examples3_Java tables. To add a data control to the form:

1. Click the data icon on the second row of the tool bar and add a data control to the form.

2. Set the following properties:
   • Load the data from a table.

   • The table is named products.

3. Set the appropriate expressions for these column names:
   • productid

   • productname

   • unitprice

4. Add a final column expression and set the Column Name to [Bandname]

5. Set the [Bandname] expression so that when the unit price is greater than 500, the data is displayed using the Band 2 format; otherwise it uses the Band 1 format like this:

     if products.unitprice > 500 then "Band2" else "Band1" endif 
   

Rules for using the [Bandname] property

1. The definition for the [Bandname] column can be a database column or a true/false expression.

2. If no bands with the specified names exist, SilverStream uses the first one that is available and the desired formatting will not be used.

3. When you create the AgcView's band formats, the names must exactly match the band names defined in the AgcData's Property Inspector.

Defining column formats for a band format   

The following code creates column formats for a band. It defines the properties of each column and appends it to the band. The following shows the code for creating one column (Product ID) of the three columns in band 1, and the same column in band 2. Note that for band 2, the column uses a different text color and a different font from that of band 1.

  //Code fragment in formActivate() 
   
     // Set the width in one place for both bands 
     int iProdIdWidth = 80; 
     int iProdNameWidth = 220; 
     int iUnitPriceWidth = 100; 
      
     // Create the format, band and column variables 
     AgoViewFormat vwFormatObject = new AgoViewFormat();  
     AgoBandFormat bndFormatObject;  
     AgoColumnText colTextObject;  
      
     // Write the code for Band1             
     bndFormatObject = new AgoBandFormat("Band1");  
   
     colTextObject = new AgoColumnText();  
     colTextObject.setPropertyName("productid");  
     colTextObject.setWidth(iProdIdWidth);  
     bndFormatObject.appendColumnFormat(colTextObject); 
     ... 
     vwFormatObject.appendBandFormat(bndFormatObject);  
     
     // Write the code for Band2 
     // this band is a different color and a different font 
     Color colObject = new Color(255, 0, 0); 
     AgoFontIdentifier fntIdObject = new AgoFontIdentifier(colTextObject.getFontIdentifier());  
   
     bndFormatObject = new AgoBandFormat("Band2");  
      
      colTextObject = new AgoColumnText();  
     colTextObject.setWidth(iProdIdWidth);  
     fntIdObject.setStyle(fntIdObject.BOLD);  
     colTextObject.setFontIdentifier(fntIdObject);  
     colTextObject.setPropertyName("productid");  
     colTextObject.setColor(colObject);  
     bndFormatObject.appendColumnFormat(colTextObject); 

Notes about the code

For band 1, create a column and set its name and its width.

• Create a band format (AgoBandFormat) object. This is band 1.

• Create the object that holds the column's properties (including text formats), AgoColumnText.

• Set the column name to "productid" by calling setPropertyName().

• Set the width of the column by calling setWidth().

• Add the column to the band format object (band 1) by calling bndFormatObject.appendColumnformat(). After each column is created, append it to band 1.

For band 2, create a column and set its name, width, font, text style, and color.

• Create a Color object and initialize it to red. (The first parameter in its constructor represents the red value. Set it to 255).

• Create a AgoFontIdentifier object that has the same font as the columns in band 1.

• Create band 2.

• Set the text style in the specified column in band 2 to the obtained font, in bold. Call setStyle to set the font style and provide fntIdObject.BOLD as the parameter.

• Set the color of the text in the column to red by calling setColor().

Adding band formats to a view format   

The following code uses appendBandFormat() to append a band to the view format. Call this method after creating each of the two bands.

  //Code fragment in formActivate() 
   
  vwFormatObject.appendBandFormat(bndFormatObject);  

Notes about the code

• bndFormatObject holds all the column formats, each appended to bndFormatObject after the column's properties were set.

• Call appendBandFormat after creating band 1 to add it to the view format. Call this method again after creating band 2 to add it to the view format as well.

Initializing a view with dynamic data and a view format   

The following code dynamically associates the view with data and the format for viewing the data.

  //Code fragment in formActivate() 
   
  vwProducts.initView(dataProduct, vwFormatObject); 

Notes about the code

• initView() associates the view with an object that provides the data and a format in which to view the data.
  • dataProduct provides the rows of data that the view will display.

  • vwFormatObject is the view format object that defines the two bands and the column formats in each of them. It contains all the code for creating column formats, appending them to bands, and appending the bands to this view format object.