Dmitriy M

The problem with this pattern is that most methods of the class now has to perform some kind of validation before doing their job.

While assuming that this code snippet is just to demonstrate the point, it always raises a question in my head: why trap every possible exceptions and then re-raise if it's not the one we are expecting, if we could just trap the one we are intrested in. try Parse; except on E: ParsingException do LogSomethingInformative; end;

Using TIdHTTP is it possible to distinguish whether POST request has been received (processed) by the server and error occurred during transmission/read of response or whether request has not been received by the server at all? I feel like my planned solution has too many assumptions and is far from perfect. begin // create and set up TIdHTTP instance IdHTTP.HTTPOptions := IdHTTP.HTTPOptions + [hoNoProtocolErrorException, hoWantProtocolErrorContent]; try // prepare request IdHTTP.Post(API_END_POINT, RequestStream, ResponseStream); // check for response code and take actions except on E: EIdSocketError do begin // connection establishment error; the request was not processed end; on E: EIdConnectTimeout do begin // connection establishment error; the request was not processed end; on E: EIdReadTimeout do begin // response read error; the request was processed end; on E: EIdConnClosedGracefully do begin // response read error; the request was processed end; end; end;

GExperts has the "Reselect desktop" expert (GExperts - Configuration - Experts tab). This expert basically reloads your currently selected IDE desktop layout. You are able to assign shortcut to trigger that expert. Not ideal solution but that does it for me.

It seems like a simple factory class could solve your issue. Let it have bunch of class methods like CreateItemsFrame, CreateUsersFrame etc. Let it know about your TProjectDataType enums that will get passed to corresponding factory methods. Main form only needs to know about this factory class. If there is some actions that needs to be taken based on what type of frame is displayed on main form, then let the frames to expose some event that main form can subscribe to and trigger this event when required.

It's not that difficult to modify REST.JsonReflect.pas to make it work in 10.2 (maybe prior versions too) procedure TJSONUnMarshal.PopulateFields {...} case revAttr.ReverterType of rtTypeObjects: begin Delete(FieldName, 1, 1); if (jsonFieldVal is TJSONArray) or (jsonFieldVal is TJSONNull) then begin // raise Exception.Create('NOT IMPLEMENTED'); SetField(Data, FieldName, revAttr.TypeObjectsReverter(GetArgObjects(LObjectType, TJSONArray(jsonFieldVal)))) end else raise EConversionError.Create(Format(SArrayExpectedForField, [FieldName, jsonFieldVal.ToString])); end; rtTypeStrings: {...} function JsonReflectAttribute.JSONInterceptor: TJSONInterceptor; begin // Result := FInterceptor.NewInstance as TJSONInterceptor;; Result := FInterceptor.Create as TJSONInterceptor; Result.ConverterType := FConverterType; Result.ReverterType := FReverterType; end; This works like a charm with @Uwe Raabe code from this post.

This is really confusing. So the new "type" section makes compiler consider class completely defined What is an explanation of this? type TMyObjectList = TObjectList<TMyObject>; TMyObjectListInterceptor = TObjectListInterceptor<TMyObject>; type // if above "type" keyword is commented out then // [dcc32 Error]: E2086 Type 'TObjectListInterceptor<T>' is not yet completely defined TMyClass = class private [JsonReflect(ctTypeObjects, rtTypeObjects, TMyObjectListInterceptor)] FContent: TMyObjectList; end;

Another non-obvious trick is that you can drag&drop selected identifier/expression (double click to select) into the watch list.

program Project1; {$APPTYPE CONSOLE} {$R *.res} uses System.SysUtils, REST.JSON, Unit1 in 'Unit1.pas'; var Person1, Person2: TPerson; jsonstr: string; begin Person1 := TPerson.Create; try Person1.Name := 'Hello'; jsonstr := Person1.SaveSettings; writeln(jsonstr); //write {"name":"Hello"} Person1.Name := 'hi'; Person1.LoadSettings(jsonstr); writeln(Person1.Name); //write Hello readln; finally Person1.Free; end; jsonstr := '{"name":"Stephane"}'; Person2 := TPerson.FromString(jsonstr); try writeln(Person2.Name); //write Stephane readln; finally Person2.Free; end; end. unit Unit1; interface type TPerson = class(TObject) private [JSONNameAttribute('NAME')] FName: string; public class function FromString(const aJsonString: String): TPerson; procedure LoadSettings(const aJsonString: String); function SaveSettings: string; property Name: string read FName write FName; end; implementation uses REST.JSON; class function TPerson.FromString(const aJsonString: String): TPerson; begin Result := TJSON.JsonToObject<TPerson>(aJsonString); end; procedure TPerson.LoadSettings(const aJsonString: String); var oJSON: TJSONObject; begin oJSON := TJSONObject.ParseJSONValue(aJsonString) as TJSONObject; try TJSON.JsonToObject(self, oJSON); finally oJSON.Free; end; end; function TPerson.SaveSettings: String; begin Result := TJSON.ObjectToJsonString(self); end; end. Reference

Take a look at FireDAC Local SQL engine. You can populate FDMemTable with data stored in your TProject records and run plain SQL queries against this dataset.