TdxBackendCustomInMemoryJSONConnection Class

The base class for JSON-based data connection components (TdxBackendInMemoryJSONConnection and TdxBackendDataSetJSONConnection).

Declaration

TdxBackendCustomInMemoryJSONConnection = class abstract(TdxBackendCustomDataConnection)

Remarks

Data connection components allow you to bind TdxDashboard/TdxDashboardControl and TdxReport/TdxReportControl components to data.

In this topic…

• Main API Members
  • Data Connection Strings
  • General-Purpose API Members
• Code Examples
  • Assign JSON Data as a Connection String
  • Assign a JSON Data String Directly
  • Load JSON Data from a Remote Source
  • Generate and Export Report Content to PDF File
• Terminal TdxBackendCustomInMemoryJSONConnection Class Descendants

Main API Members

The list below outlines key members of the TdxBackendCustomInMemoryJSONConnection 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 in the 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.

SetJSONValue

Sets component data to the specified JSON value.

General-Purpose API Members

Collection | Index

Specify the parent collection component.

Code Examples

Assign JSON Data as a Connection String

The following code example demonstrates an OnClick event handler that configures a TdxBackendInMemoryJSONConnection component, assigns a table defined within a JSON string to the ConnectionString property, and displays the Dashboard Designer dialog:

Delphi

uses
  dxDashboard.Control,              // Declares the TdxDashboardControl component
  dxBackend.ConnectionString.JSON;  // Declares the TdxBackendInMemoryJSONConnection component
// ...

procedure TMyForm.cxDisplayDesignerButtonClick(Sender: TObject);
begin
  // Specify a user-friendly data connection name (for end-user dialogs):
  dxBackendInMemoryJSONConnection1.DisplayName := 'Memory-Based JSON Data Source';
  // Define a table that consists of three columns ("id", "Region", and "Sales") and five data rows:
  dxBackendInMemoryJSONConnection1.ConnectionString := 'Json=''' +

    '[{"id": 1, "Region": "Asia",          "Sales": 4.7685},' +  // Row #1
     '{"id": 2, "Region": "Australia",     "Sales": 1.9576},' +  // Row #2
     '{"id": 3, "Region": "Europe",        "Sales": 3.3579},' +  // Row #3
     '{"id": 4, "Region": "North America", "Sales": 3.7477},' +  // Row #4
     '{"id": 5, "Region": "South America", "Sales": 1.8237}]'''; // Row #5

  dxDashboardControl1.ShowDesigner;  // Displays the "Dashboard Designer" dialog
end;

C++

#include "dxDashboard.Control.hpp"              // Declares the TdxDashboardControl component
#include "dxBackend.ConnectionString.JSON.hpp"  // Declares the TdxBackendInMemoryJSONConnection component

// Add the following linker directives to the corresponding CPP source file:
#pragma link "dxDashboard.Control"              // Required to use dxDashboard.Control.hpp declarations
#if defined(_WIN64)  // Required to use dxBackend.ConnectionString.JSON.hpp declarations
  #pragma link "dxBackend.ConnectionString.JSON.o"
#else
  #pragma link "dxBackend.ConnectionString.JSON.obj"
#endif
// ...

void __fastcall TMyForm::cxDisplayDesignerButtonClick(TObject *Sender)
{
  // Specify a user-friendly data connection name (for end-user dialogs):
  dxBackendInMemoryJSONConnection1->DisplayName = "Memory-Based JSON Data Source";
  // Define a table that consists of three columns ("id", "Region", and "Sales") and five data rows:
  dxBackendInMemoryJSONConnection1->ConnectionString = "Json=\"\""

    L"[{\"id\": 1, \"Region\": \"Asia\",          \"Sales\": 1.9576},"     // Row #1
     L"{\"id\": 2, \"Region\": \"Australia\",     \"Sales\": 1.9576},"     // Row #2
     L"{\"id\": 3, \"Region\": \"Europe\",        \"Sales\": 3.3579},"     // Row #3
     L"{\"id\": 4, \"Region\": \"North America\", \"Sales\": 3.7477},"     // Row #4
     L"{\"id\": 5, \"Region\": \"South America\", \"Sales\": 1.8237}]\"\"" // Row #5

  dxDashboardControl1->ShowDesigner();          // Displays the "Dashboard Designer" dialog
}

Assign a JSON Data String Directly

The following code example demonstrates an OnClick event handler that calls the SetJSONValue procedure to assign a table defined within a JSON string to the TdxBackendInMemoryJSONConnection component and displays the Dashboard Designer dialog:

Delphi

uses
  dxDashboard.Control,              // Declares the TdxDashboardControl component
  dxBackend.ConnectionString.JSON;  // Declares the TdxBackendInMemoryJSONConnection component
// ...

procedure TMyForm.cxDisplayDesignerButtonClick(Sender: TObject);
var
  AJSONData: string;
begin
  // Define a table that consists of three columns ("id", "Region", and "Sales") and five data rows:
  AJSONData :=

  '[{"id": 1, "Region": "Asia",          "Sales": 4.7685},' +  // Row #1
   '{"id": 2, "Region": "Australia",     "Sales": 1.9576},' +  // Row #2
   '{"id": 3, "Region": "Europe",        "Sales": 3.3579},' +  // Row #3
   '{"id": 4, "Region": "North America", "Sales": 3.7477},' +  // Row #4
   '{"id": 5, "Region": "South America", "Sales": 1.8237}]';   // Row #5

  // Specify a user-friendly data connection name (for end-user dialogs):
  dxBackendInMemoryJSONConnection1.DisplayName := 'Memory-Based JSON Data Storage';
  dxBackendInMemoryJSONConnection1.SetJSONValue(AJSONData);  // Assigns the defined JSON data string
  dxDashboardControl1.ShowDesigner;                          // Displays the Dashboard Designer dialog
end;

C++

#include "dxDashboard.Control.hpp"              // Declares the TdxDashboardControl component
#include "dxBackend.ConnectionString.JSON.hpp"  // Declares the TdxBackendInMemoryJSONConnection component

// Add the following linker directives to the corresponding CPP source file:
#pragma link "dxDashboard.Control"              // Required to use dxDashboard.Control.hpp declarations
#if defined(_WIN64)  // Required to use dxBackend.ConnectionString.JSON.hpp declarations
  #pragma link "dxBackend.ConnectionString.JSON.o"
#else
  #pragma link "dxBackend.ConnectionString.JSON.obj"
#endif
// ...

void __fastcall TMyForm::cxDisplayDesignerButtonClick(TObject *Sender)
{
  // Define a table that consists of three columns ("id", "Region", and "Sales") and five data rows:
  UnicodeString AJSONData =

    L"[{\"id\": 1, \"Region\": \"Asia\",          \"Sales\": 1.9576},"  // Row #1
     L"{\"id\": 2, \"Region\": \"Australia\",     \"Sales\": 1.9576},"  // Row #2
     L"{\"id\": 3, \"Region\": \"Europe\",        \"Sales\": 3.3579},"  // Row #3
     L"{\"id\": 4, \"Region\": \"North America\", \"Sales\": 3.7477},"  // Row #4
     L"{\"id\": 5, \"Region\": \"South America\", \"Sales\": 1.8237}]"  // Row #5

  // Specify a user-friendly data connection name (for end-user dialogs):
  dxBackendInMemoryJSONConnection1->DisplayName = "Memory-Based JSON Data Source";
  dxBackendInMemoryJSONConnection1->SetJSONValue(AJSONData);  // Assigns the defined JSON data string
  dxDashboardControl1->ShowDesigner();                        // Displays the "Dashboard Designer" dialog
}

Load JSON Data from a Remote Source

The code example in this section demonstrates an OnClick event handler that configures a TdxBackendInMemoryJSONConnection component used to load JSON data from an external source using a connection string and displays the Dashboard Designer dialog.

Note

This code example demonstrates a sample connection string. You must replace specified parameter values with required URI, username, password, access tokens, etc.

Delphi

uses
  dxDashboard.Control,              // Declares the TdxDashboardControl component
  dxBackend.ConnectionString.JSON;  // Declares the TdxBackendInMemoryJSONConnection component
// ...

procedure TMyForm::cxDisplayDesignerButtonClick(Sender: TObject);
begin
  dxBackendInMemoryJSONConnection1.Active := False;  // Terminates the current connection (if one exists)
  // Specify a user-friendly data connection name (for end-user dialogs):
  dxBackendInMemoryJSONConnection1.DisplayName := 'Memory-Based JSON Data Source';
  dxBackendInMemoryJSONConnection1.ConnectionString :=

    'Uri=https://northwind.netcore.io/customers.json;' + // Specifies the path to a source JSON file
    'Username=user;' +                      // Specifies a valid user name
    'Password=pwd;' +                       // Specifies the corresponding password for the user name
    'MyAuthHeader1=secretToken1;MyAuthHeader2=secretToken2;' +  // Specifies authentication tokens
    'query:id=123456;query:name=MyName;'    // Specifies the required query ID and name

  dxBackendInMemoryJSONConnection1.Active := True;   // Connects to the target Web service endpoint
  dxDashboardControl1.ShowDesigner();                // Displays the "Dashboard Designer" dialog
end;

C++

#include "dxDashboard.Control.hpp"              // Declares the TdxDashboardControl component
#include "dxBackend.ConnectionString.JSON.hpp"  // Declares the TdxBackendInMemoryJSONConnection component

// Add the following linker directives to the corresponding CPP source file:
#pragma link "dxDashboard.Control"              // Required to use dxDashboard.Control.hpp declarations
#if defined(_WIN64)  // Required to use dxBackend.ConnectionString.JSON.hpp declarations
  #pragma link "dxBackend.ConnectionString.JSON.o"
#else
  #pragma link "dxBackend.ConnectionString.JSON.obj"
#endif
// ...

void __fastcall TMyForm::cxDisplayDesignerButtonClick(TObject *Sender)
{
  dxBackendInMemoryJSONConnection1->Active = false; // Terminates the current connection (if one exists)
  // Specify a user-friendly data connection name (for end-user dialogs):
  dxBackendInMemoryJSONConnection1->DisplayName = "Memory-Based JSON Data Source";
  dxBackendInMemoryJSONConnection1->ConnectionString =

    L"Uri=https://northwind.netcore.io/customers.json;"  // Specifies the path to a source JSON file
    L"Username=user;"                      // Specifies a valid user name
    L"Password=pwd;"                       // Specifies the corresponding password for the user name
    L"MyAuthHeader1=secretToken1;MyAuthHeader2=secretToken2;"  // Specifies authentication tokens
    L"query:id=123456;query:name=MyName;"  // Specifies the required query ID and name

  dxBackendInMemoryJSONConnection1->Active = true;  // Connects to the target Web service endpoint
  dxDashboardControl1->ShowDesigner();              // Displays the "Dashboard Designer" dialog
}

Generate and Export Report Content to PDF File

The following code example configures a memory-based data source (TdxBackendInMemoryJSONConnection), loads an XML layout, and exports generated content to a file in the Portable Document (PDF) format without user interaction:

Delphi

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

procedure TMyForm.cxButtonExportToPDFClick(Sender: TObject);
var
  AReport: TdxReport;
  AJSONDataConnection: TdxBackendInMemoryJSONConnection;
  AMemoryStream: TMemoryStream;
  AJSONData: string;
begin
  // Define a table that consists of three columns ("id", "Region", and "Sales") and five data rows:
  AJSONData :=

  '[{"id": 1, "Region": "Asia",          "Sales": 4.7685},' +  // Row #1
   '{"id": 2, "Region": "Australia",     "Sales": 1.9576},' +  // Row #2
   '{"id": 3, "Region": "Europe",        "Sales": 3.3579},' +  // Row #3
   '{"id": 4, "Region": "North America", "Sales": 3.7477},' +  // Row #4
   '{"id": 5, "Region": "South America", "Sales": 1.8237}]';   // Row #5

  AJSONDataConnection := TdxBackendInMemoryJSONConnection.Create(Self);  // Creates a data connection
  try
    AJSONDataConnection.Name := 'JSONData';        // Assigns a name to the created data connection
    AJSONDataConnection.SetJSONValue(AJSONData);   // Assigns the defined JSON data string
    AReport := TdxReport.Create(Self);       // Creates a TdxReport container
    try
      AReport.Layout.LoadFromFile('MyReportLayout.xml');  // Loads an XML Report layout
      AReport.ReportName := 'MyReport';                         // Defines a Report name
      AMemoryStream := TMemoryStream.Create;                    // Creates a memory stream
      TdxSplashFormManager.WaitForm.Show(Self);    // Displays a Wait Form before the export operation
      try
        // Export Report content to the created memory stream in the PDF format:
        AReport.ExportToPDF(AMemoryStream);
        AMemoryStream.SaveToFile(AReport.ReportName + '.pdf');   // Saves the resulting PDF file
      finally
        AMemoryStream.Free;         // Releases the memory stream
        TdxSplashFormManager.WaitForm.Hide;        // Hides the Wait Form once the operation is complete
      end;
    finally
      AReport.Free;              // Releases the TdxReport container
    end;
  finally
    AJSONDataConnection.Free;       // Releases the data connection
  end;
end;

C++

#include "dxBackend.ConnectionString.JSON.hpp"  // Declares the TdxBackendInMemoryJSONConnection component
#include "dxSplashForms.hpp"                    // Declares the TdxSplashFormManager class and related types
#include "dxReport.hpp"                      // Declares the TdxReport class

// Add the following linker directives to the corresponding CPP source file:
#pragma link "dxReport"                      // Required to use dxReport.hpp declarations
#if defined(_WIN64)  // Required to use dxBackend.ConnectionString.JSON.hpp declarations
  #pragma link "dxBackend.ConnectionString.JSON.o"
#else
  #pragma link "dxBackend.ConnectionString.JSON.obj"
#endif
// ...

void __fastcall TMyForm::cxButtonExportToPDFClick(TObject *Sender)
{
  TdxReport *AReport;
  TdxBackendInMemoryJSONConnection *AJSONDataConnection;
  TMemoryStream *AMemoryStream;

  // Define a table that consists of three columns ("id", "Region", and "Sales") and five data rows:
  UnicodeString AJSONData =

  "[{\"id\": 1, \"Region\": \"Asia\",          \"Sales\": 1.9576},"  // Row #1
   "{\"id\": 2, \"Region\": \"Australia\",     \"Sales\": 1.9576},"  // Row #2
   "{\"id\": 3, \"Region\": \"Europe\",        \"Sales\": 3.3579},"  // Row #3
   "{\"id\": 4, \"Region\": \"North America\", \"Sales\": 3.7477},"  // Row #4
   "{\"id\": 5, \"Region\": \"South America\", \"Sales\": 1.8237}]"  // Row #5

  AJSONDataConnection = new TdxBackendInMemoryJSONConnection(this);  // Creates a data connection
  try
  {
    AJSONDataConnection->Name = "JSONData";        // Assigns a name to the created data connection
    AJSONDataConnection->SetJSONValue(AJSONData);  // Assigns the defined JSON data string
    AReport = new TdxReport(this);           // Creates a TdxReport container
    try
    {
      AReport->Layout->LoadFromFile("MyReportLayout.xml");  // Loads an XML Report layout
      AReport->ReportName = "MyReport";                           // Defines a Report name
      AMemoryStream = new TMemoryStream();                        // Creates a memory stream
      TdxSplashFormManager::WaitForm()->Show(this);  // Displays a Wait Form before the export operation
      try
      {
        // Export Report content to the created memory stream in the PDF format
        AReport->ExportToPDF(AMemoryStream);
        AMemoryStream->SaveToFile(AReport->ReportName + ".pdf");  // Saves the resulting PDF file
      }
      __finally
      {
        delete AMemoryStream;       // Releases the memory stream
        TdxSplashFormManager::WaitForm()->Hide();    // Hides the Wait Form once the operation is complete
      }
    }
    __finally
    {
      delete AReport;            // Releases the TdxReport container
    }
  }
  __finally
  {
    delete AJSONDataConnection;     // Releases the data connection
  }
}

Terminal TdxBackendCustomInMemoryJSONConnection Class Descendants

Do not use the TdxBackendCustomInMemoryJSONConnection class directly. Use the following components instead:

TdxBackendInMemoryJSONConnection

A component designed for interaction with data stored in memory.

TdxBackendDataSetJSONConnection

A component designed to fetch data from one or multiple datasets (TDataSet descendant instances).

Inheritance

TObject

TPersistent

TComponent

TcxCustomComponent

TcxComponentCollectionItem

TdxBackendCustomDataConnection

TdxBackendCustomInMemoryJSONConnection