Microsoft Outlook 2003 - Article 01 Programming Forms with VBScript.pdf - books - kris320

Article 1

Programming Forms with

VBScript

Understanding Scripting . . . . . . . . . . . . . A2

A Brief Overview of VBScript. . . . . . . . . . A2

Understanding Objects and

Properties . . . . . . . . . . . . . . . . . . . . . . . . A2

Understanding Events and Methods . . . . A4

Creating Scripts and Using the

Editor. . . . . . . . . . . . . . . . . . . . . . . . . . . . A4

Referencing Controls. . . . . . . . . . . . . . . . A6

Using Methods . . . . . . . . . . . . . . . . . . . . A7

Event Handling . . . . . . . . . . . . . . . . . . . . A9

Using Variables. . . . . . . . . . . . . . . . . . . . A9

Using Constants . . . . . . . . . . . . . . . . . . A11

Retrieving and Setting Field

Values. . . . . . . . . . . . . . . . . . . . . . . . . . A11

Retrieving User-Defined and Other

Properties. . . . . . . . . . . . . . . . . . . . . . . A12

For More Information on VBScript

and Outlook . . . . . . . . . . . . . . . . . . . . . A16

You can often develop a reasonably powerful custom solution in Microsoft Office Outlook

2003 simply by creating and using Outlook forms with standard and custom controls. How-

ever, this approach has limits. For example, what if you want a new task to be created every

time a user sends your custom form? What if you want to send a meeting request when your

form is submitted? What if you want to connect to a database and fill in a drop-down list on

your form with values from a specific database table?

Although it isn’t practical to explain how to code for all these problems in this introductory

chapter, the preceding list offers good examples of some of the tasks that are difficult, if not

impossible, to accomplish using only custom forms that have no underlying custom program

code. This chapter looks at developing custom form solutions with computer code and cus-

tom fields. You’ll strengthen your understanding of programming basics and learn how you

can begin to apply this understanding to developing a custom Outlook solution.

To create a solution that involves working with dynamic data, launching new items, and ani-

mating other programs, you could search for a control that already has these behaviors built

in. However, don’t spend too much time looking, because you’re unlikely to find a control

with functionality so specifically tailored to your needs. The way to create powerful forms is

by writing code.

For some people, writing code in an Outlook solution simply means learning the syntax of

Microsoft Visual Basic, Scripting Edition (VBScript) and some of the properties, methods,

and events of Outlook and Outlook forms. For other people, writing code might seem much

more daunting. No matter what your level of programming experience is, this chapter pro-

vides some basic knowledge you need to begin programming Outlook forms.

Microsoft Office Outlook 2003 Inside Out

Understanding Scripting

Programming languages such as C++, Microsoft Visual Basic, VBScript, and C# (pro-

nounced “C sharp”) provide access to computer resources at different levels. The basic rule is

that the “lower” you go, the more you need to know. Think of it as similar to programming

a microwave: when you enter a combination of settings to defrost a chicken that weighs 1.3

pounds, you’re programming the oven to do certain things. At a lower level, a program inside

the microwave takes the settings you provide and translates them into a cooking plan that the

machine can execute. Most often, lower level programming languages, which are usually

designed for speed and scalability, are used to create sophisticated, complex applications.

However, the learning curve for these languages can be prohibitive for someone who wants to

simply use some controls to create a form that sends an e-mail message. This is where a

higher level language such as VBScript steps in, giving the power of programming to users

who don’t have extensive backgrounds in computer science.

As the name implies, VBScript is a scripting language . A scripting language can create an

unlimited number of programmatic solutions relatively quickly. Always remember, however,

that you are trading true power and performance for simplicity and speed of development.

Unlike a compiled programming language, a scripted language is interpreted—that is, the

statements of instruction are reduced to a simple sequence of statements that are then exe-

cuted by what is called a command interpreter . For each scripting language, a corresponding

scripting engine provides this interpreter, along with other basic services to execute the

script. When you program Outlook forms, you don’t need to do anything to install this

engine or ensure that your scripts will actually be executed. Outlook has this engine built in;

all you need to do is open the Script Editor and begin writing code.

Because Outlook uses VBScript as the language for form development, you need to know the

syntax of VBScript. You also need to know which interfaces are available for you to manipu-

late with lines of code. The next section provides this information.

A Brief Overview of VBScript

VBScript is a subset of the Microsoft Visual Basic programming language. The VBScript

engine is portable, which means the engine can be embedded in or used by many different

programs, such as Microsoft Internet Explorer or Outlook. As mentioned earlier, VBScript is

already embedded in Outlook. You can begin writing form-based code, and those who use

your forms will benefit from the code behind the forms without installing anything special to

make the forms work. Because the VBScript engine is a true subset of the complete Visual

Basic language, it is less complex and therefore easier to learn.

Understanding Objects and Properties

Object is probably one of the most overused words in the world of computer programming.

Over time, the word has come to represent many different things to people in the IT field.

Because the focus of this book is not hard-core computer science, this chapter is relatively

introductory and covers only what you need to get your Outlook solution moving along. In

Programming Forms with VBScript

this context, the following section discusses the notion of an object and what it means to your

Outlook solution.

Objects

At the simplest level, an object in your Outlook development environment represents Out-

look, the program itself, and other elements in Outlook (such as a text box) that expose prop-

erties, methods, or events with which you can interact programmatically. Outside the world

of computing, the definition of an object is widely understood. For example, you know that

a book is an object. It has certain properties such as height, weight, color, number of pages,

title, author, and so on. You can also perform certain actions with a book: you can open it,

close it, turn pages one at a time, flip to the end, return to the beginning, and fold the corners

to mark your location.

A significant aspect of programming a custom solution using VBScript or Microsoft Visual

Basic for Applications (VBA) is manipulating Outlook items. For example, you add a text

box to a form and then add or change the text it displays by setting a property of that text box

object. You display or close a form by using a Show or Hide method on the form, treating the

form as a complete object rather than showing or hiding the individual controls on the form.

When a user clicks a button on a form, that button object generates a Click event. You add the

code you want Outlook to execute when the button is clicked.

Thinking of Outlook items as programmable objects will help you begin to understand how

you can create custom solutions with VBScript and VBA. Don’t think of your custom pro-

gram as pages and pages of program code. Instead, think of it as a collection of forms, con-

trols, and other objects with properties you can set, either at design time or through program

code when the form runs, to make it perform the tasks you intend.

Properties

Properties are attributes of an object, describing some aspect of how an object behaves. To

return to an earlier analogy, an object in Outlook can have some of the same properties as a

book. For example, a form has height, width, and other basic properties that describe appear-

ance. A command button has properties such as height, width, position, caption, name, and

color. The more you know about the properties of the objects you use, the more you can do

with those objects. To set a property of an object, you must reference the object and follow it

with a period and then the name of the property. The following code sample shows how to set

the property of an object:

cmdAddAppointment.Caption = "Add Appt."

In this example, assume that your form contains a command button named cmdAddAppoint-

ment . You manipulate the Caption property of that button by setting it to some new value.

How do you know that the button has this property? For any given object, you must read

documentation to know the available properties and other behaviors for that object. For

example, a text box does not have a Caption property, but a label does; both these controls

have a Font property.

Microsoft Office Outlook 2003 Inside Out

Notice that in the preceding example the Caption property required a string of characters

between quotes. This is because the Caption property is predefined to accept characters

strung together and not numbers, bitmaps, or other kinds of data. When you work with

properties, you need to learn which types of data each property accepts to accurately apply

property settings for your objects.

Understanding Events and Methods

Events and methods are two other powerful behaviors of a form or other object in Outlook. To

continue with the previous analogy, you can do a number of things with a book: you can

open it, close it, and so on. Put another way, the book possesses a number of methods, such

as OpenBook , CloseBook , Tu r n Pa g e , GoToEnd , GoToBeginning , and AddBookMark . These

method names are intuitive. The creators of any object model usually give intuitive names to

the methods that their object exposes.

You can also associate certain events with a book. For example, when you finish reading the

book, you might have to return it to the library. When you open the book for the first time,

you might have to remove the book’s dust jacket. To return to the microwave analogy, when

the microwave completes the cooking plan you’ve provided, this event causes an alarm to

sound. In other words, the microwave has a CookingPlanCompleted event that fires when the

time runs out. When this event occurs, the alarm sounds.

In the world of Outlook development, you’ll interact with many objects, some of which

expose certain events. Arguably, the most common event to fire is some kind of Click event,

which fires when a user clicks a command button or other control. Notice the terminology:

an event fires when something else happens. This is important to remember, because it is easy

to get methods and events confused. Just remember that methods are actions you can take

with an object, whereas events fire in response to an action—perhaps in response to a

method or the changing of a property setting.

Creating Scripts and Using the Editor

Now that you have a little background information about the properties, methods, and

events of the objects you can include in your solution, you’re ready to begin writing code.

Where do you write it? Theoretically, you can write the code in any program you want—in

Microsoft Word, Notepad, or any other text editor. However, where you write the code is not

as important as where it must reside to be able to run. Outlook has a window, or code editor,

where all code must be placed before it can run. To access this code editor in Outlook, choose

Form, View Code when your form is open. You can also click the View Code button to the

right of the Control Toolbox button. In either case, the window shown in Figure A1-1

appears. Any code that you want to run for your Outlook form must be contained in this

window.

Programming Forms with VBScript

FA1ok01

Figure A1-1. You can write and run the code for your form in the Script Editor window.

Inside Out

Outlook Object Library Help

The Outlook Script Editor provides roughly the same level of functionality as Notepad or

another basic text editor. However, the menu bar of this editor does contain the Outlook

Object Library Help, shown in Figure A1-2. The Object Library will come in handy as you

develop your programming skills in Outlook. To access this help, choose Help, Microsoft

Outlook Object Library Help from the editor’s command bar. It’s helpful to take some time

to understand the Outlook object model.

FA1ok02

Figure A1-2. Use Outlook Object Library Help when writing code for Outlook.

Microsoft Outlook 2003 - Article 01 Programming Forms with VBScript.pdf

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