RAD Server Academy Course – lecture 7 extract – Returning JSON using JSONValue and JSONWriter.

I've uploaded an extract of me RAD Server Embarcadero Academy course Lecture 7 – Returning JSON using JSONValue and JSONWriter. This video clips will give you an example of one of the lectures that are included in the Delphi and C++ courses.

The clips (on my YouTube channel) show you how to use JSONWriter to output rows and columns of database data as JSON data.

There are clips for Delphi and C++Builder:

• Delphi – https://youtu.be/yyd3Ikpjinw
• C++Builder – https://youtu.be/PfhxEghEFTE

Delphi Source Code:

interface

uses
  System.SysUtils, System.Classes, System.JSON,
  EMS.Services, EMS.ResourceAPI, EMS.ResourceTypes, FireDAC.Stan.Intf,
  FireDAC.Stan.Option, FireDAC.Stan.Error, FireDAC.UI.Intf, FireDAC.Phys.Intf,
  FireDAC.Stan.Def, FireDAC.Stan.Pool, FireDAC.Stan.Async, FireDAC.Phys,
  FireDAC.Phys.IB, FireDAC.Phys.IBDef, FireDAC.ConsoleUI.Wait,
  FireDAC.Stan.Param, FireDAC.DatS, FireDAC.DApt.Intf, FireDAC.DApt,
  FireDAC.Stan.StorageJSON, Data.DB, FireDAC.Comp.DataSet, FireDAC.Comp.Client,
  FireDAC.Comp.BatchMove.JSON, FireDAC.Comp.BatchMove,
  FireDAC.Comp.BatchMove.DataSet;

type
  [ResourceName('FireDAC')]
  TFireDACResource1 = class(TDataModule)
    DatabaseConnection: TFDConnection;
    EmployeeQuery: TFDQuery;
    FDStanStorageJSONLink1: TFDStanStorageJSONLink;
    EmployeeQueryEMP_NO: TSmallintField;
    EmployeeQueryFIRST_NAME: TStringField;
    EmployeeQueryLAST_NAME: TStringField;
    EmployeeQueryPHONE_EXT: TStringField;
    EmployeeQueryHIRE_DATE: TSQLTimeStampField;
    EmployeeQueryDEPT_NO: TStringField;
    EmployeeQueryJOB_CODE: TStringField;
    EmployeeQueryJOB_GRADE: TSmallintField;
    EmployeeQueryJOB_COUNTRY: TStringField;
    EmployeeQuerySALARY: TFMTBCDField;
    EmployeeQueryFULL_NAME: TStringField;
  published
    procedure Get(const AContext: TendpointContext;
	const ARequest: TEndpointRequest; const AResponse: TEndpointResponse);
    [ResourceSuffix('{item}')]
    procedure GetItem(const AContext: TendpointContext;
	const ARequest: TEndpointRequest; const AResponse: TEndpointResponse);
  end;

implementation

{%CLASSGROUP 'System.Classes.TPersistent'}

uses
  System.JSON.Types;

{$R *.dfm}

procedure TFireDACResource1.Get(const AContext: TendpointContext;
	const ARequest: TEndpointRequest; const AResponse: TEndpointResponse);
var
  RowCount,FieldIndex : integer;
begin
  EmployeeQuery.Close();
  EmployeeQuery.SQL.Clear();
  EmployeeQuery.SQL.Add('select * from employee');
  EmployeeQuery.Open();

  // set the JSONWriter formatting to indented
  AResponse.Body.JSONWriter.Formatting := TJSONFormatting.Indented;

  // using JSONWriter to craft custom JSON return for all rows
  AResponse.Body.JSONWriter.WriteStartArray;
  for RowCount := 0 to EmployeeQuery.RecordCount-1 do begin
    AResponse.Body.JSONWriter.WriteStartObject;

    for FieldIndex := 0 to EmployeeQuery.FieldCount-1 do begin
      Aresponse.Body.JSONWriter.WritePropertyName(
		EmployeeQuery.Fields[FieldIndex].FieldName);
 	Aresponse.Body.JSONWriter.WriteValue(
	  EmployeeQuery.FieldByName(
	    EmployeeQuery.Fields[FieldIndex].FieldName).AsString)
    end;
    AResponse.Body.JSONWriter.WriteEndObject;
    EmployeeQuery.Next
  end;
  AResponse.Body.JSONWriter.WriteEndArray;
end;

procedure TFireDACResource1.GetItem(const AContext: TEndpointContext; const ARequest: TEndpointRequest; const AResponse: TEndpointResponse);
var
  FieldIndex : integer;
  LItem : string;
begin
  LItem := ARequest.Params.Values['item'];
  EmployeeQuery.Close();
  EmployeeQuery.SQL.Clear();
  EmployeeQuery.SQL.Add('select * from employee where EMP_NO = '+LItem);
  EmployeeQuery.Open();

  // set the JSONWriter formatting to indented
  AResponse.Body.JSONWriter.Formatting := TJSONFormatting.Indented;

  // using JSONWriter to craft custom JSON return for the selected employee row
  AResponse.Body.JSONWriter.WriteStartObject;
  for FieldIndex := 0 to EmployeeQuery.FieldCount-1 do begin
    Aresponse.Body.JSONWriter.WritePropertyName(
	EmployeeQuery.Fields[FieldIndex].FieldName);
    Aresponse.Body.JSONWriter.WriteValue(
	EmployeeQuery.FieldByName(
	  EmployeeQuery.Fields[FieldIndex].FieldName).AsString)
  end;
end;

procedure Register;
begin
  RegisterResource(TypeInfo(TFireDACResource1));
end;

C++ Source Code:

//---------------------------------------------------------------------------
#pragma hdrstop

#include "DMUnit.h"
#include <memory>
//---------------------------------------------------------------------------
#pragma package(smart_init)
#pragma classgroup "System.Classes.TPersistent"
#pragma resource "*.dfm"
//---------------------------------------------------------------------------
__fastcall TFireDACResource1::TFireDACResource1(TComponent* Owner)
	: TDataModule(Owner)
{
}

void TFireDACResource1::Get(TEndpointContext* Acontext,
		TEndpointRequest* Arequest, TEndpointResponse* AResponse)
{
	EmployeeQuery->Close();
	EmployeeQuery->SQL->Clear();
	EmployeeQuery->SQL->Add("select * from employee");
	EmployeeQuery->Open();
	// set the JSONWriter formatting to indented
	AResponse->Body->JSONWriter->Formatting = TJsonFormatting::Indented;
	// using JSONWriter to craft custom JSON return for all rows
	AResponse->Body->JSONWriter->WriteStartArray();
	for (int RowCount = 0; RowCount < EmployeeQuery->RecordCount; RowCount++) {
		AResponse->Body->JSONWriter->WriteStartObject();
		for (int FieldIndex = 0; FieldIndex < EmployeeQuery->FieldCount;
				 FieldIndex++) {
			AResponse->Body->JSONWriter->WritePropertyName(
				EmployeeQuery->Fields->Fields[FieldIndex]->FieldName);
			AResponse->Body->JSONWriter->WriteValue(
				EmployeeQuery->FieldByName(
					EmployeeQuery->Fields->Fields[FieldIndex]
						->FieldName)->AsString);
	}
	AResponse->Body->JSONWriter->WriteEndObject();
	EmployeeQuery->Next();
  }
  AResponse->Body->JSONWriter->WriteEndArray();
}

void TFireDACResource1::GetItem(TEndpointContext* Acontext,
		TEndpointRequest* ARequest, TEndpointResponse* AResponse)
{
	String item;
	item = ARequest->Params->Values["item"];
	EmployeeQuery->Close();
	EmployeeQuery->SQL->Clear();
	EmployeeQuery->SQL->Add("select * from employee where EMP_NO = "+item);
	EmployeeQuery->Open();
	// set the JSONWriter formatting to indented
	AResponse->Body->JSONWriter->Formatting = TJsonFormatting::Indented;
	// using JSONWriter to craft custom JSON for the selected employee row
	for (int FieldIndex = 0; FieldIndex < EmployeeQuery->FieldCount;
			 FieldIndex++) {
	  AResponse->Body->JSONWriter->WritePropertyName(
		EmployeeQuery->Fields->Fields[FieldIndex]->FieldName);
	  AResponse->Body->JSONWriter->WriteValue(
		EmployeeQuery->FieldByName(
			EmployeeQuery->Fields->Fields[FieldIndex]
				->FieldName)->AsString);
	}
}

static void Register()
{
       	std::auto_ptr<TEMSResourceAttributes> attributes(
			new TEMSResourceAttributes());
       	attributes->ResourceName = "FireDAC";
       	attributes->ResourceSuffix["GetItem"] = "{item}";
       	RegisterResource(__typeinfo(TFireDACResource1), attributes.release());
}

#pragma startup Register 32

Watching the Academy lecture videos, reading the lecture course notes and working with the example code you’ll learn the following:

• RAD Server’s application development tips and techniques
• RAD Server’s platform requirements
• How to build and test your first RAD Server applications
• How to deploy your RAD Server applications to Windows+IIS and Linux+Apache
• The new RAD Server features in RAD Studio 10.3 Rio releases
• How to build client applications using RAD Studio and Sencha EXT JS to access your RAD Server endpoints
• What sample projects and application templates are available for RAD Server to help get you started
• Where to find additional references, resources, videos, blog posts and more

Courses:

Using Delphi and RAD Server to Rapidly Design, Build, Debug, and Deploy Services-Based Solutions
https://www.embarcaderoacademy.com/p/delphi-and-rad-server

Using C++Builder and RAD Server to Rapidly Design, Build, Debug, and Deploy Services-Based Solutions
https://www.embarcaderoacademy.com/p/cpp-and-rad-server