Visual Studio Tools for Office: Using C# with Excel, Word, Outlook, and InfoPath [Electronic resources] نسخه متنی

Introduction to the Excel Object Model

Regardless of the approach you choose to integrate your code with Excel, you will eventually need to talk to the Excel object model to get things done. It is impossible to completely describe the Excel object model in this book, but we try to make you familiar with the most important objects in the Excel object model and show some of the most frequently used methods, properties, and events on these objects.

The Object Hierarchy

The first step in learning the Excel object model is getting an idea for the basic structure of the object model hierarchy. Figure 3-16 shows the most critical objects in the Excel object model and their hierarchical relationship.

A Workbook object has a collection called Sheets. The Sheets collection can contain objects of type Worksheet or Chart. A Chart is sometimes called a chart sheet because it covers the entire area that a worksheet would cover. You can insert a chart sheet into a workbook by right-clicking the worksheet tabs in the lower-left corner of the Excel workbook and choosing Insert. Figure 3-17 shows the dialog that appears. Note that two additional objects are found in the Sheets collection: MS Excel 4.0 macro sheets and MS Excel 5.0 dialog sheets. If you insert a macro sheet or dialog sheet into an Excel workbook, it is treated as a special kind of worksheetthere is not a special object model type corresponding to a macro sheet or a dialog sheet.

Because a workbook can contain these various kinds of objects, Excel provides several collections off of the Workbook object. The Worksheets collection contains just the Worksheet objects in the workbook. The Charts collection contains just the chart sheets in the workbook. The Sheets collection is a mixed collection of both. The Sheets collection returns members of the collection as type objectyou must cast the returned object to a Worksheet or Chart. In this book, when we talk about an object that could be either a Worksheet or a Chart, we refer to it as a sheet.

Figure 3-18 shows a more complete hierarchy tree with the major objects associated with the objects in Figure 3-16. This starts to give you an idea of the extensive hierarchy of objects that is the Excel object model, especially when you realize that this diagram shows less than half of the objects available. The objects shown in gray are coming from the Microsoft.Office.Core namespace, which is associated with the Microsoft Office 11.0 PIA (office.dll). These objects are shared by all the Office applications.