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Retrieve a Subset of Contacts on a BlackBerry Device

Exercise

Retrieve a subset of contacts on a BlackBerry® device by designing a screen with choice control with an initial value property set to a subset of contacts. The WHERE clause determines a subset of contacts (for example, WHERE nameFamily=@gv_Name). In this example, contacts that have the field nameFamily equal to the global variable string gv_Name display in the choice control. The screen maps the choice control to a local variable, contact, of type Contact. Use similar screens and constructs for the keyed built-in data components to display subsets of these data collections.

Objectives

• Discover how to retrieve a subset of contacts on a BlackBerry device.

Setup Tasks

Create an application that can access the local address book. See the lab entitled Create a Contact Using the Top-Down Approach for more details.

Open BlackBerry MDS Studio™ and select the Contact Viewer project which you created in the previous lab. See the lab entitled Create a Contact Using the Top-Down Approach and Display Contact Information for more details.

If you have not completed the first two labs in this series, create the Contact Viewer project following these steps:

1. Download the Contact Viewer workspace (ZIP) and unzip the file.
2. Import the Contact Viewer workspace to BlackBerry MDS Studio
   Click File menu -> Import Existing… -> Browse -> select Contact Viewer -> Finish

Tasks

Create a global variable

1. In the Navigator pane, expand Data.
2. Right-click Globals.
3. Click New Global.
4. In the Name field, type a name, for example, gv_name.
5. Click Finish.

Create a contact screen with a contact local variable

1. In the Navigator pane, create a new screen (i.e. scrSubContact).
2. In the Screen Editor, click on the screen canvas.
3. In the Properties pane, in the Local Variables property, click ....
4. Click +.
5. In the Name cell, type contact.
6. In the Type drop-down list, click Contact.
7. Click OK.

Note: You can now assign screen controls to the screen local variable contact, which is an instance of the built-in data component Contact.

Create the contact list lookup field

1. Create a choice control.
2. In the list of available data, expand Collections > Built-in > Contact.
3. Click nameFamily.
4. Click Apply.
5. In the expression field, click in the brackets of the expression @Contact[].nameFamily.
6. In the Field drop-down list, click nameFamily.
7. In the Operator drop-down list, click =.
8. Perform one of the following actions:

9. Click OK.
10. In the Properties pane, in the Mapping property, click ....
11. Expand Local Variables.
12. In the list of available data, click contact.
13. Click OK.

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