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Monday, February 26, 2018One very cool feature of TMS RADical WEB (if not the main one) is that it allows Delphi developers to build Web applications that do not need a server connection. It's just HTML and JS files that run in the browser.
But we all know that there are some applications that need to retrieve data from somewhere, and also eventually persist data. We do not need a server to "run" the application, but we eventually might need communicate to a server to ask for data, perform centralized operations, authentication, etc.
While you can use any API server you want from the Web application, when using TMS XData to build the server your life will be way easier:
- First, because with TMS XData you can write your backend server using Delphi and Pascal.
- Also, because TMS XData is simply way too productive - it's very easy and fast to publish entities directly from database and to create service operations in a snap.
- And, finally, because TMS XData provides first class support to TMS WEB Core, providing components that make it very easy and straightforward to connect to a XData server
The following screenshot shows the TMS XData Web Client demo in action. It's a sample that connects to a public XData REST server that holds information about music artists, albums, genres and tracks. With this demo you can retrieve and modify data from this server.
Note that this demo is dynamic. It means you can simply change the URL of server and it will work with any TMS XData Server you might have, regardless of the entities it publishes. The server provides the metadata for the whole API, and the client loads it at runtime allowing you to access the API in a very high level.
Also design-time components are available for you to simply assign properties and set handlers for the events that will fire when the server request is finished.
In case you're curious about how it's accomplished, here is the full source code for the implementation section of the single unit of the demo. The interface part was removed just because it's a bunch of declarations of the visual control fields.
procedure TForm1.btDeleteClick(Sender: TObject); begin XDataWebClient1.Delete(SelectedEntitySet, TJSObject(TJSJSON.parse(DeleteMemo.Lines.Text))); end; procedure TForm1.btGetClick(Sender: TObject); begin XDataWebClient1.Get(SelectedEntitySet, SelectedId); end; procedure TForm1.btListClick(Sender: TObject); begin XDataWebClient1.List(SelectedEntitySet, edQuery.Text); end; function TForm1.SelectedEntitySet: string; begin Result := cbEntitySets.Items[cbEntitySets.ItemIndex]; end; function TForm1.SelectedId: Integer; begin Result := StrToInt(edId.Text); end; procedure TForm1.ShowInfo(const Msg: string; Error: Boolean); begin InfoLabel.Caption := Msg; if Error then InfoLabel.Font.Color := clRed else InfoLabel.Font.Color := clWindowText; InfoLabel.Visible := True; end; procedure TForm1.btPostClick(Sender: TObject); begin XDataWebClient1.Post(SelectedEntitySet, TJSObject(TJSJSON.parse(PostMemo.Lines.Text))); end; procedure TForm1.btPutClick(Sender: TObject); begin XDataWebClient1.Put(SelectedEntitySet, TJSObject(TJSJSON.parse(PutMemo.Lines.Text))); end; procedure TForm1.WebFormCreate(Sender: TObject); begin ServerLabel.Caption := Format('XData Server URL: %s', [XDataConnection1.URL]); XDataConnection1.LoadModel; end; procedure TForm1.XDataConnection1ModelLoad(Sender: TObject); var Container: TXDataEntityContainer; I: Integer; begin Container := XDataConnection1.Model.DefaultEntityContainer; cbEntitySets.Items.Clear; for I := 0 to Container.EntitySets.Count - 1 do cbEntitySets.Items.Add(Container.EntitySets[I].Name); if cbEntitySets.Items.Count > 0 then cbEntitySets.ItemIndex := 0; end; procedure TForm1.XDataWebClient1Error(Error: TXDataClientError); begin ShowInfo( Format('%s. RequestId: %s. Code: %s. Request Url: %s', [Error.ErrorMessage, Error.RequestId, Error.ErrorCode, Error.RequestUrl]), True ); end; procedure TForm1.XDataWebClient1Load(Response: TXDataClientResponse); begin InfoLabel.Visible := False; if Response.RequestId = 'get' then GetMemo.Lines.Text := TJSJson.stringify(Response.Result) else if Response.RequestId = 'list' then ListMemo.Lines.Text := TJSJson.stringify(Response.Result) else if Response.RequestId = 'post' then ShowInfo(Format('New entity created in %s collection.', [SelectedEntitySet])) else if Response.RequestId = 'put' then ShowInfo(Format('Entity updated in %s collection.', [SelectedEntitySet])) else if Response.RequestId = 'delete' then ShowInfo(Format('Entity removed from %s collection.', [SelectedEntitySet])); end;
Get started today: Technical previews of TMS WEB Core, TMS FNC UI web-enabled controls, web-enabled TMS XData, the first parts under the TMS RADical WEB umbrella are exclusively available now for all active TMS-ALL-ACCESS customers.
Wagner R. Landgraf
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