True DataControl Objects and Collections

True DataControl provides a rich set of properties, methods, and events that enable you to develop sophisticated database applications with much less manual coding than using conventional data source controls. The organization imposed by True DataControl object model makes it easier to work with its large feature set.

Objects and collections that refer to True DataControl entities, such as fields, can be customized at design time or run time. Objects and collections that refer to abstract entities, such as arrays and bookmarks, are only available in code at run time.

When you add a True DataControl file to a Visual Basic project, the True DataControl (TData) is added to the Toolbox:

TData

ComponentOne True DataControl

In the Lite version, it will be

TDataLite

ComponentOne True DataControl Lite

The type library for True DataControl 8.0 (its short name is TrueData60Ctl, or TrueDataLite70Ctl for the Lite version 8.0) also contains definitions for the following objects:

NamedBookmark	Represents a bookmark appearing in the list in the Bookmarks dialog.
Constraint	Represent a field-level or record-level constraint.
Field	Represents a True DataControl field.
FilterExpression	Represents a filter expression.
Parameter	Represents a True DataControl parameter.
PropertyExpression	Represents a control property expression.
RangeCondition	Represents a field’s range condition (unavailable in the Lite version).
RowBuffer	Transfers data to and from user mode events (unavailable in the Lite version).

A collection is an object used to group similar objects. Since a collection itself is an object, you can manipulate it in code just as you would any other object. The type library for True DataControl 8.0 contains definitions for the following collections:

NamedBookmarks	Contains zero or more NamedBookmark objects.
Constraints	Contains zero or more Constraint objects.
Fields	Contains zero or more Field objects.
FilterExpressions	Contains zero or more FilterExpression objects.
Parameters	Contains zero or more Parameter objects.
PropertyExpressions	Contains zero or more PropertyExpression objects.
RangeConditions	Contains zero or more RangeCondition objects.

When using True DataControl memory array mode (DataMode = 1 – MemoryArray), you also need to add a reference to the ComponentOne XArrayDB Object to your project. This is not a control, but a reference that defines a single object:

XArrayDB

Variant array used as a data source in storage mode.

The following sections provide a brief overview of True DataControl objects and collections.