mORMot Open Source

Subject : JSON record array on Android

Hello All,

I have been able to manipulate JSON array of records on Windows.

However, on Android I can not generate the array of records from the JSON.

This pseudo code works on Windows :-

  TMyRecord = record
    CompanyId : String;
    ClientId  : String;
  end;

  TRecArray = record
    MyRecArray : array of TMyRecord;
  end;

  Rec1     : TMyRecord;
  Rec2     : TMyRecord;
  JsonStr  : String;
  RecArray : TRecArray;
begin
  Rec1.CompanyId := 'Company1';
  Rec1.ClientId  := 'Client1';

  Rec2.CompanyId := 'Company2';
  Rec2.ClientId  := 'Client2';

  JsonStr := '{"MyRecArray":[';
  JsonStr := JsonStr +
             SynCommons.RecordSaveJSON(
                          Rec1,
                          TypeInfo(TMyRecord));
  JsonStr := JsonStr + ',' +
             SynCommons.RecordSaveJSON(
                          Rec2,
                          TypeInfo(TMyRecord));
  JsonStr := JsonStr + ']}';

  SetLength(RecArray.MyRecArray, 2);
  bResult := SynCommons.RecordLoadJSON(
                            RecArray,
                            JsonStr,
                            TypeInfo(TRecArray));
end;

On Android I can get the JSON using :-

var
  RecVariant : Variant;
begin
  JsonStr := '{"MyRecArray":[';

  RecVariant := TMyRecord2Variant(Rec1);

  JsonStr := JsonStr +
             SynCrossPlatformJSON.ValueToJSON(RecVariant);

  RecVariant := TMyRecord2Variant(Rec2);

  JsonStr := JsonStr + ',' +
             SynCrossPlatformJSON.ValueToJSON(RecVariant);

  JsonStr := JsonStr + ']}';

  {The JsonStr is the same as on Windows}
end;

Now on Android generating the array of records (This does not work) :-

begin
  RecVariant := SynCrossPlatformJSON.JSONToValue(JsonStr);

  RecArray := Variant2MyRecordArray(RecVariant, 2); {Error in this call}
end;
 

function Variant2MyRecordArray(var   aRecVariant  : Variant;
                               const aRecsInArray : Integer) : TRecArray;
var
  iIterate : Integer;
  Str      : String;
begin
  if aRecsInArray <= 0 then begin
    SetLength(Result.MyRecArray, 0);
    Exit;
  end;
  SetLength(Result.MyRecArray, aRecsInArray);
  for iIterate := 0 to (aRecsInArray - 1) do begin
    Str := aRecVariant.MyRecArray[iIterate].CompanyId; {Error - Variant method calls not supported}

    Result.MyRecArray[iIterate].CompanyId := Str;
    ...
  end;
end;       

This last part in Android doesn't work.
Perhaps there is a simpler way to achieve this on Android?

Any ideas?

Regards,
  Peter G. Evans

I have successfully made a Delphi 10.1 Berlin, mORMot Windows Server.
Also a Windows FireMonkey Client can successfully log on and log off my system. This is excellent.

I have one parameter which is an object TMemSettingObj.

It is defined like:-

type
  TMemSettingObj = class
  private
  ...

So far so good.

When I make the Android FireMonkey Client I create the unit mORMotClient using a
server wrapper project.

On Android there are a few problems. For example,

  MemSettingObj := TableMemSettingObj.TMemSettingObj.CreateFromVariant(res[7]);

I get an error :-

  'TMemSettingObj' does not contain a member named 'CreateFromVariant'.

So I defined TMemSettingObj with conditional compilation:-

type
  TMemSettingObj = class
{$IFDEF SERVERWRAPPER}
                        (TSQLRecord)
{$ENDIF}
  private
  ...

The program now compiles under Android.

However when the Server runs I get error:_

TSQLRestRoutingREST.Error: {  "errorCode":406,  "errorText":"(sicShared) execution failed
(probably due to bad input parameters) for LoginAdmin.LoginAdmin"  }

Comparing the Log with the Log used to call from Windows FireMonkey Client the main differences are:

Android gets a prefix of    "ID":0,
  (I understand this as the class now descends from TSQLRecord)

Windows - "MainViewTimelineShow":true
Android - "MainViewTimelineShow":1

Do you have any tips on how I can get it working on both Windows and Android?

Regards,
  Peter Evans

1)
The following is an extract from generated mORMotClient.
(I have stripped out some unnecessary parameters from the extract.)
The object TMemSettingObj is one I have devised.

Against this line :-

  MemSettingObj := TableMemSettingObj.TMemSettingObj.CreateFromVariant(res[7]);

I get an error :-

  'TMemSettingObj' does not contain a member named 'CreateFromVariant'.

  /// implements ILoginAdmin from http://localhost:888/root/LoginAdmin
  // - this service will run in sicShared mode
  TServiceLoginAdmin = class(TServiceClientAbstract,ILoginAdmin)
  public
    constructor Create(aClient: TSQLRestClientURI); override;
    function LoginAdmin(const Company1: String; ... var ServerTime: TDateTime; var MemSettingObj: TableMemSettingObj.TMemSettingObj): Boolean;
  end;

function TServiceLoginAdmin.LoginAdmin(const Company1: String; ... var ServerTime: TDateTime; var MemSettingObj: TableMemSettingObj.TMemSettingObj): Boolean;

var res: TVariantDynArray;
begin
  fClient.CallRemoteService(self,'LoginAdmin',9, // raise EServiceException on error
    [Company1, ... DateTimeToIso8601(ServerTime),ObjectToVariant(MemSettingObj)],res);
  LoginInfoInt := res[0];
  ...
  ServerTime := Iso8601ToDateTime(res[6]);
  MemSettingObj.Free; // avoid memory leak
  MemSettingObj := TableMemSettingObj.TMemSettingObj.CreateFromVariant(res[7]);
  Result := res[8];
end;

What do you suggest I need to do to fix this problem?

2)
The object TMemActiveObj is one I have devised.

Against this line :-

  [Company1,Name1,Token1,ObjectToVariant(MemActiveObj),iLastAutoInc],res);

I get an error :-

  Incompatible types: 'TSQlRecord' and 'TMemActiveObj'.

/// implements ILogoffAdmin from http://localhost:888/root/LogoffAdmin
  // - this service will run in sicShared mode
  TServiceLogoffAdmin = class(TServiceClientAbstract,ILogoffAdmin)
  public
    constructor Create(aClient: TSQLRestClientURI); override;
    function LogoffAdmin(const Company1: String; const Name1: String; const Token1: Integer; const MemActiveObj: TableMemActiveObj.TMemActiveObj; var iLastAutoInc: Integer): Boolean;
  end;

function TServiceLogoffAdmin.LogoffAdmin(const Company1: String; const Name1: String; const Token1: Integer; const MemActiveObj: TableMemActiveObj.TMemActiveObj; var iLastAutoInc: Integer): Boolean;
var res: TVariantDynArray;
begin
  fClient.CallRemoteService(self,'LogoffAdmin',2, // raise EServiceException on error
    [Company1,Name1,Token1,ObjectToVariant(MemActiveObj),iLastAutoInc],res);
  iLastAutoInc := res[0];
  Result := res[1];
end;

What do you suggest I need to do to fix this problem?

Regards,
  Peter Evans

There are a number of projects in Sample 27. This is my experience with them.

I am using Delphi 10.1 Berlin.

a) Project 'MobileClient.dpr'.

In MobileMain.pas need to comment out the line 51 :-
    assert(json = ...

Then the program works on Android machine - Google Nexus 7.
Does not need a server to work.

b) Project 'FMClient.dpr'.

In FMMain.pas need to comment out the line 101 :-
   assert(json = ...

On Android machine - Google Nexus 7. When run get an
   EOpenError 'Cannot open file "/people.json".

I changed the name of the file from 'People.json' to 'people.json'. Then added
the file to the Deployment tab. (On Deployment tab I made the Remote Path = .\
I got the same error.

I then amended the code to read :-

USES
  System.IOUtils;

  {
  FN := 'people.json';
  for level := 1 to 4 do
    if FileExists(FN) then
      break else
      FN := IncludeTrailingPathDelimiter('..')+FN;
  }
  FN := TPath.GetDocumentsPath + PathDelim + 'people.json';

When run I get an error in function UTF8FileToString in unit
SynCrossPlatformJSON. The function is unable to find the file.

I am not sure why this is so.

c) Project14ServerHttpWrapper  [in this Sample 27]

To get this to work I had to place the files from
CrossPlatform/templates in the following hierarchy :-

    Folder For My Project\Project14ServerHttpWrapper
    CrossPlatform\template\copied files

Regards,
  Peter Evans

I get the error - Undeclared identifier : AnsiString.

This points to AnsiString in :-

  function CompressGZip(var DataRawByteString; Compress: boolean): AnsiString;

in the unit SynZip.

When I compile the Client with FireMonkey on Windows these are the DCU generated:-

mORMot
mORMotHttpClient
SynBidirSock
SynCommons
SynCrtSock
SynCrypto
SynLog
SynLZ
SynSSPlAuth
SynTests
SynWinSock
SynZip.

I have read 'ReadMe.txt'.
I note that there are these Include files available: 'Synopse.inc', 'SynCrossPlatform.inc'.

I note that mORMot pulls in SynZip.

I placed in the Android client under Project | Options the 'Conditional defines' NEXTGEN.

Is there another conditional defines I need to use?

Should I be replacing some units with some from the CrossPlatform folder?

Regards,
  Peter Evans

My understanding is probably lacking in some areas.

I copied methods from my DataSnap program, and, rewrote them as methods using Interfaces.

I then realized that some of the methods have calls to SQL queries etc. They are against
the database ElevateDB from Elevate Software. (Aside - Apparantly there is an ODBC driver available from Elevate Software.) There is only one main database.

In Project 14 there is the TServiceCalculator with function Add. That function doesn't call
a database.

In DataSnap there is a form :-

   TServerMethods1 = class(TDSServerModule)

On the form I have components for :-
  Session, Database, Tables, Queries etc.

Here is an example of an existing DataSnap method converted to mORMot.
It does SQL queries within the method :-

  TLogoffAdmin = class(TInterfacedObject, ILogoffAdmin)
  public
    function LogoffAdmin(const Company1     : String;
                         const Name1        : String;
                         const Area1        : Integer;
                         const MemObj       : TMemObj;
                         var   iLastAutoInc : Integer) : Boolean;
  end;

What sample do you think I need to look at so that methods accessing the main database
can be successfully called?

Regards,
  Peter Evans

Last week I downloaded mORMot and successfully got all the Tests to work.
I am very impressed with what I see.

I want to migrate a DataSnap program. It uses methods on the Server and
Client to communicate. The Server is Delphi VCL. One Client is FireMonkey
on Windows. Another Client is FireMonkey on Android.

So I am investigating Interface based services.

I have run Sample "14 - Interface based services". (Running on Windodws 10)

There are 3 options:-
1) HTTP / TCP-IP
2) Named Pipe
3) Weak HTTP / TCP-IP.

I can get option 2) to work.
But option 1) and option 3) I get an error. This is like :-

  Server not available - { "EWinHTTP":"winhttp.dll error 12029 (A
  connection with the server could not be established)" }

Is this a Windows permissions problem of some kind?

How do I go about pinpointing the error?

Regards,
  Peter Evans