Arrays (Delphi)

Overview

This sample demonstrates how to use Arrays and Structs for representing database tables and a master/detail relationship.

Prerequisites

The sample works with the Northwind database, which has to be available on the localhost server with Windows credentials. In order to adjust the DB connection settings, select the ArraysServerMain form, double-click the TADOConnection component and build the connection string:

Getting Started

  • Compile and launch the server.
  • Compile and run the client.
  • Click the 'Open' button and both master and detail table views will be filled with data.
  • Select different rows in the master table view and see how the data changes in the detail table view.

Examine the Code

The GetTables method returns a structure containing two arrays:

function TArraysService.GetTables: Tables;
begin
  Result := Tables.Create;
  // Customers
  ArraysServerMainForm.tblCustomers.Close;
  ArraysServerMainForm.tblCustomers.Open;
  ArraysServerMainForm.tblCustomers.First;
  while not ArraysServerMainForm.tblCustomers.Eof do begin
    with Result.aCustomers.Add do begin
      CustomerID := ArraysServerMainForm.tblCustomers.FieldByName('CustomerID').AsString;
      CompanyName := ArraysServerMainForm.tblCustomers.FieldByName('CompanyName').AsString;
      // ... and other fields used the same way
    end;
    ArraysServerMainForm.tblCustomers.Next;
  end;
  ArraysServerMainForm.tblCustomers.Close;
  // orders
  // similar to Customers
  ...
end;

These arrays contain data from the Customers and Orders tables and consist of structs matching the table structures:

Customers = class(TROComplexType)
  ...
  published
    property CustomerID: UnicodeString read fCustomerID write fCustomerID;
    property CompanyName: UnicodeString read fCompanyName write fCompanyName;
    // ... similar properties for other fields
  end;
  ...
{ CustomersArray }
  CustomersArray_Customers = array of Customers;
  CustomersArray = class(TROArray)
  private
    fCount: Integer;
    fItems: CustomersArray_Customers;
  ...
  end;
...

Tables = class(TROComplexType)
  ...
  published
    property aCustomers: CustomersArray read GetaCustomers write faCustomers;
    property aOrders: OrdersArray read GetaOrders write faOrders;
  end;

Concepts Covered