TdxReportControlResolveConnectionEvent Type

The procedural type for manual data connection resolution events in a TdxReportControl component.

Declaration

TdxReportControlResolveConnectionEvent = procedure(ASender: TdxCustomReportControl; const ADisplayName: string; var AConnection: TdxBackendCustomDataConnection) of object;

Parameters

Name	Type	Description
ASender	TdxCustomReportControl	Provides access to the Report control that raised the data connection resolution event. Tip Cast the ASender parameter value to the TdxReportControl class to access all public API members.
ADisplayName	string	Returns the target data connection name (DisplayName) referenced in the current scope (Viewer or Designer).
AConnection	TdxBackendCustomDataConnection	Specifies the data connection component that corresponds to the currently processed data connection name (ADisplayName) within the current report layout definition. The initial AConnection parameter value provides access to the automatically identified source data connection component for the ADisplayName value. You can use the AConnection parameter to manually select a specific connection component as the data source associated with the processed connection name (ADisplayName) for the current TdxReportControl component (ASender).

Remarks

The TdxReportControlResolveConnectionEvent procedural type is designed for manual data connection resolution in a TdxReportControl component when two or more data connection components share the same display name.

An application can contain multiple data connection components (TdxBackendCustomDataConnection descendants) with the same DisplayName property value used to address these components in a report layout definition.

Automatic Data Connection Name Resolution

If the manual data connection resolution event is unhandled, the TdxReportControl component resolves data component display names automatically:

Unique Component Display Names

The TdxReportControl uses data connection components with corresponding display names as data sources.

Multiple Matching Component Display Names

The TdxReportControl component iterates through all data connection components and searches the first component with the target display name in the following order:

• On the same form as the TdxReportControl.
• On a data module (TDataModule descendant instance).
• Any other data connection with the same display name.

Manual Data Connection Name Resolution/Event Occurrence

The manual data connection resolution event occurs every time a TdxReportControl component is about to access available data sources (in the Viewer or Designer scope):

TdxReportControl | Report Viewer

Viewer Scope. The manual data connection resolution event occurs when TdxReportControl/Report Viewer populates or updates placeholders within the layout definition with data – once per active data connection component referenced within the layout.

Report Designer

Designer Scope. The manual data connection resolution event occurs once for each active (that is, available to the Report Designer dialog) data connection component within the application.

You can assign a data connection component to the AConnection parameter within a TdxReportControlResolveConnectionEvent handler to manually map the component to the referred display name for the current data access/load operation.

In addition, you can assign nil (in Delphi) or nullptr (in C++Builder) to the AConnection parameter to hide the currently processed connection in the Report Designer dialog.

Note

• The manual data connection resolution event occurs even if the application or template/layout definition contains only one active data connection component (or multiple data connection components with unique DisplayName property values). You can remap a unique display name to another data connection component if necessary.
• This event never occurs for inactive data access components.

Direct TdxReportControlResolveConnectionEvent Type Reference

The TdxCustomReportControl.OnResolveConnection event references the TdxReportControlResolveConnectionEvent procedural type.