TdxBackendInMemoryJSONConnection Class

A component designed for interaction with data stored in memory.

Declaration

TdxBackendInMemoryJSONConnection = class(
    TdxBackendCustomInMemoryJSONConnection
)

Remarks

A data connection component allows you to bind a backend client component to data.

Main API Members

The list below outlines key members of the TdxBackendInMemoryJSONConnection class. These members allow you to configure core data connection settings.

Data Connection Settings

Active

Specifies if the data connection is active.

DisplayName

Specifies the data connection’s name both in report/UI layout template designer and Collection Editor dialogs.

The DisplayName property value is used to specify the data connection name within report/UI layout templates.

ConnectionString

Specifies a connection string (or stores serialized data in the JSON format).

Tip

Refer to the following topic for detailed information on JSON Data: Connection to a JSON Data Source.

General-Purpose API Members

Collection | Index: Specify the parent collection component.

Code Example: Generate Reports Based on In-Memory Data

The following code example loads an XML-based report template (TdxReport.Layout) from a REPX file, populates the template with test data defined in a connection string, and exports the resulting report as a PNG image:

Delphi
C++

uses
  dxReport,  // Declares the TdxReport component and related types
  dxBackend.ConnectionString.JSON;  // Declares the TdxBackendInMemoryJSONConnection component
// ...

procedure TMyForm.Button1Click(Sender: TObject);
var
  AJSONDataConnection: TdxBackendInMemoryJSONConnection;
  AReport: TdxReport;
  AFileStream: TFileStream;
begin
  AJSONDataConnection := TdxBackendInMemoryJSONConnection.Create(Self);
  try
    AJSONDataConnection.Name := 'JSONData';
    // Specify in-memory report data as a connection string
    AJSONDataConnection.ConnectionString :=
      'Json=''[{"id":1, "caption":"test1"},{"id":2, "caption":"test2"}]''';
    AReport := TdxReport.Create(Self);
    try
      AReport.ReportName := 'Report';
      AReport.Layout.LoadFromFile('Report.repx');  // Loads a report template
      AFileStream := TFileStream.Create('Report.png', fmOpenReadWrite);
      try
        AReport.ExportToImage(AFileStream);  // Exports the report in the default image export format (PNG)
      finally
        AFileStream.Free;
      end;
    finally
      AReport.Free;
    end;
  finally
    AJSONDataConnection.Free;
  end;
end;

#include "dxReport.hpp"  // Declares the TdxReport component
#include "dxBackend.ConnectionString.JSON.hpp"  // Declares the TdxBackendInMemoryJSONConnection component

// Add the following linker directives to the corresponding CPP source file:
#pragma link "dxReport"  // Required for dxReport.hpp declarations
#pragma link "dxBackend.ConnectionString.JSON" // Required for dxBackend.ConnectionString.JSON.hpp declarations
// ...

void __fastcall TMyForm::Button1Click(TObject *Sender)
{
  TdxBackendInMemoryJSONConnection *AJSONDataConnection;
  TdxReport *AReport;
  TFileStream *AFileStream;
  AJSONDataConnection = new TdxBackendInMemoryJSONConnection(this);
  try
  {
    AJSONDataConnection->Name = "JSONData";
    // Specify in-memory report data as a connection string
    AJSONDataConnection->ConnectionString =
      "Json=\"\"[{\"id\":1, \"caption\":\"test1\"}, {\"id\":2, \"caption\":\"test2\"}]\"";
    AReport = new TdxReport(this);
    try
    {
      AReport->ReportName = "Report";
      AReport->Layout->LoadFromFile("Report.repx");  // Loads a report template
      AFileStream = new TFileStream('Report.png', fmOpenReadWrite);
      try
      {
        AReport->ExportToImage(AFileStream);  // Exports the report in the default image export format (PNG)
      }
      __finally
      {
        delete AFileStream;
      }
    }
    __finally
    {
        delete AReport;
    }
  }
  __finally
  {
    delete AJSONDataConnection;
  }
}

Indirect TdxBackendInMemoryJSONConnection Class References

The following public API members reference the TdxBackendInMemoryJSONConnection class as a TdxBackendCustomDataConnection object:

TdxBackendDataConnectionCollection.Add: Creates a data connection of the required type and ads the connection to the collection.
TdxBackendDataConnectionCollection.Items: Provides indexed access to all data connection components stored in the collection.
TdxBackendDataConnectionManager.Items: Provides indexed access to stored data connection components.

Other Report Data Connection Components

TdxBackendDataSetJSONConnection: A component designed to fetch data from one or multiple datasets (TDataSet descendant instances).
TdxBackendDatabaseSQLCOnnection: A component designed to fetch data from an SQL database (SQL Server, PostgreSQL, SQLite, etc.).

To see TdxDashboardControl and TdxReport components in action, run BI Dashboards Designer/Viewer and Report Designer/Viewer demos in the VCL Demo Center installed with compiled VCL DevExpress demos. Click different items in the sidebar on the left to switch between demo features.

Download: Compiled VCL Demos

Tip

You can find full source code for installed compiled Report and Dashboard demos in the following folders:

%PUBLIC%\Documents\DevExpress VCL Demos\MegaDemos\Product Demos\ExpressReports\
%PUBLIC%\Documents\DevExpress VCL Demos\MegaDemos\Product Demos\ExpressDashboards\