Delphi REST fill out RESTResponse - rest

Question

I'm working on a DElphi FMX project where I make a lot of requests to a REST backend.
I'm using one TRESTClient, and are dynamically creting a TRESTRequest every time I ask for something, my plan is to make it multitreading to make the UI be more responsive.
I have made a function called DoRequest, that do the actual request, it looks like something this:
Function TFormMain.Dorequest(Meth:TRESTRequestmethod;Url,RequestBody:String;
Var Respons: TCustomRESTResponse):Boolean;
Var
par: TRESTRequestParameter;
Req : TRESTRequest;
begin
Req := TRESTRequest.Create(RESTClient);
With Req do
try
if RequestBody<>'' then
begin
Params.Clear;
par := Params.AddItem('body',RequestBody);
par.ContentType := ctAPPLICATION_JSON;
par.Kind := pkREQUESTBODY;
end;
Method := Meth;
Resource := Url;
Execute;
Respons := Response;
Result := Respons.StatusCode In [200,201];
finally
Req.Free; // <-Error here
end;
end;
I call it like this:
procedure TFormUser.Button1Click(Sender: TObject);
Var
Respons: TCustomRESTResponse;
begin
If DoRequest(rmPOST,CreateUserUrl,JSON,Respons) then
begin
ShowMessage('User '+EdEmail.Text+' created');
ModalResult := MrOk;
end
However, I get an Acces Violation when freeing Req, my TRESTRequest.
I found out that it is because the TCustomRESTResponse Respons is just made a pointer to the memory where the Req.Response is placed, so freeing Req also destroys Respons.
My question is: How do I make a copy of Req.Response that lives after Req is freed?
I have tried Respons.Assign(Response), but it gives the rather strange error: "Cannot assign a TCustomRESTResponse to a TFormMain"
Am I doing this the wrong way, also keeping in mind that I would like the actual request to be in another tread?
Michael

Answer 1

When you don't link your own TRESTResponse to the client, the client will create one of its own and also free it. If you create your own TRESTResponse and assign it, the client will leave it alone, and you can free it whenever you want.
That said, like I mentioned in the comment, I think it's probably better to let the thread deal with deserializing the response, and have it pass a more generic class or record holding the relevant information (a value object, if you're into that), rather than passing around the specific TRESTResponse.