TdxBackendCustomInMemoryJSONConnection.ConnectionString Property

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

Declaration

property ConnectionString: string read; write;

Property Value

Type	Description
string	The connection string or serialized data in the JSON format.

Remarks

The ConnectionString property serves different purposes for TdxBackendInMemoryJSONConnection and TdxBackendDataSetJSONConnection components (TdxBackendCustomInMemoryJSONConnection descendants).

In this topic…

• Component-Specific Property Behavior
  • In-Memory JSON Connection Component
  • Dataset-Based JSON Connection Component
• Code Examples
  • Assign JSON Data as a Connection String
  • Load JSON Data from a Remote Source
  • Load Data from a DevExpress JSON Sample
  • Generate and Export Report Content to PDF File
• Default Value

Component-Specific Property Behavior

In-Memory JSON Connection Component

ConnectionString is the main property^[1] in the TdxBackendInMemoryJSONConnection class. You can use this property to:

• Specify required data as a JSON string.
• Specify a Web Service Endpoint URL or a path to the required JSON file.

Dataset-Based JSON Connection Component

The ConnectionString property stores serialized JSON data from datasets associated with the TdxBackendDataSetJSONConnection component. Use the DataSets property to bind and configure one or multiple datasets (TdxMemData, TFDTable, TFDQuery, etc.).

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
}

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
}

Load Data from a DevExpress JSON Sample

The following code example uses a sample JSON file hosted on GitHub by DevExpress as a data source for the TdxBackendInMemoryJSONConnection component:

Delphi

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

procedure TMyForm.cxDisplayDesignerButtonClick(Sender: TObject);
var
  AUri: string;
begin
  AUri := 'Uri=https://raw.githubusercontent.com/DevExpress-Examples/DataSources/master/JSON/customers.json';
  // Specify a user-friendly data connection name (for end-user dialogs):
  dxBackendInMemoryJSONConnection1.DisplayName := 'Memory-Based JSON Data Storage';
  dxBackendInMemoryJSONConnection1.ConnectionString := AUri;  // Assigns the target Web Service URI
  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)
{
  UnicodeString AUri;
  AUri = "Uri=https://raw.githubusercontent.com/DevExpress-Examples/DataSources/master/JSON/customers.json";
  // Specify a user-friendly data connection name (for end-user dialogs):
  dxBackendInMemoryJSONConnection1->DisplayName = "Memory-Based JSON Data Source";
  dxBackendInMemoryJSONConnection1->ConnectionString = AUri;  // Assigns the target Web Service URI
  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
  }
}

Default Value

The ConnectionString property’s default value is an empty string.

Footnotes

1. Available in the Object Inspector.