Json Array of String: Wie Array-Items per Schleife auslesen

[Uwe Raabe]

Diesen Ansatz mit dem JSON-Class-Mapping kann man auch ohne externe Bibliothek nur mit Delphi-Bordmitteln realisieren:

Delphi-Quellcode:

interface

uses
  System.Types,
  REST.Json.Types;  // wegen des Attributs

type
  TDBSettings = class
  type
    TDataBase = class
    private
      [JSONName('DB-Name')]
      FDBName: String;
      [JSONName('DB-Provider')]
      FDBProvider: Integer;
      FDBServerName: String;
      [JSONName('DB-User')]
      FDBUser: String;
      [JSONName('DB-User-Pw')]
      FDBUserPw: Integer;
    public
      property DBName: String read FDBName write FDBName;
      property DBProvider: Integer read FDBProvider write FDBProvider;
      property DBServerName: String read FDBServerName write FDBServerName;
      property DBUser: String read FDBUser write FDBUser;
      property DBUserPw: Integer read FDBUserPw write FDBUserPw;
    end;
  private
    FDatabase: TDataBase;
  public
    ShorthandSymbol: TStringDynArray;
    constructor Create;
    destructor Destroy; override;
    class function LoadFromFile(const pmcFileName: string): TDBSettings;
    procedure SaveToFile(const pmcFileName: string);
    property Database: TDataBase read FDatabase;
  end;

implementation

constructor TDBSettings.Create;
begin
  inherited Create;
  FDatabase := TDataBase.Create();
end;

destructor TDBSettings.Destroy;
begin
  FDatabase.Free;
  inherited Destroy;
end;

In der Anwendung sieht das dann in etwa so aus:

Delphi-Quellcode:

uses
  System.IOUtils, System.SysUtils,
  REST.Json;

const
  cFileName = 'c:\temp\settings.json';

begin
  var settings := TJson.JsonToObject<TDBSettings>(string.Join(sLineBreak, cArr));
  try
    TFile.WriteAllText(cFileName, TJson.ObjectToJsonString(settings));
  finally
    settings.Free;
  end;

begin
  var settings := TJson.JsonToObject<TDBSettings>(TFile.ReadAllText(cFileName));
  try
    ...
  finally
    settings.Free;
  end;
end;

Nebenbei: Das StringArray als Feld anstatt Property ist zumindest zu hinterfragen.