[SOLVED] LAMW - App crash with TMySQL57ConnectionBridge
lazarus / 43-Android

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Alcatiz · 2024-05-12 08:27

Hi all!

I'm trying to make a simple app to handle a MySQL/MariaDB database
stored on my local network. The app can connect to the database but as
soon as I try to activate the SQLTransaction the app crashes:
Code: Pascal  [Select][+][-]window.onload = function(){var x1 =
document.getElementById("main_content_section"); if (x1) { var x =
document.getElementsByClassName("geshi");for (var i = 0; i procedure
TAndroidModule1.Button1Click(Sender: TObject);begin 
MySQL57ConnectionBridge1.HostName := '192.168.1.40'; 
MySQL57ConnectionBridge1.Port := 3306; 
MySQL57ConnectionBridge1.DatabaseName := 'xxx'; 
MySQL57ConnectionBridge1.UserName := 'xxx'; 
MySQL57ConnectionBridge1.Password := 'xxx';  if
MySQL57ConnectionBridge1.Connect     then       begin       
 EditText1.AppendLn('Connected!');         if
MySQL57ConnectionBridge1.SQLTransaction.Active            then       
     EditText1.AppendLn('Transaction is active!')            else    
        EditText1.AppendLn('Transaction is NOT active...');         //
MySQL57ConnectionBridge1.SQLTransaction.Active := True;   (* CRASH *) 
     end     else       EditText1.AppendLn('Error...');end;
When the last line is commented, the app returns "Connected!" and
"Transaction is NOT active...", so it seems the SQLTransaction is
correctly allocated.
If I replace the TMySQL57ConnectionBridge component with SQLDB
components (TMySQL57Connection, TSQLTransaction and TSQLQuery) the app
also crashes.
The same app compiled on Linux on another PC connected to the local
network doesn't encounter any problem.
Connection to the database on my smartphone with any MySQL client is
successfull.

So any ideas? Thx!

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biologic · 2024-05-12 18:17

Hi.

Maybe you should put a begin-end statement around your instructions.

Just a guess.


Code: [Select]if MySQL57ConnectionBridge1.Connect
     then
       begin
         EditText1.AppendLn('Connected!');
         if MySQL57ConnectionBridge1.SQLTransaction.Active
            then
              EditText1.AppendLn('Transaction is active!')
            else
              begin
                   EditText1.AppendLn('Transaction is NOT active...');
                   MySQL57ConnectionBridge1.SQLTransaction.Active :=
True;   (* CRASH *)
               end
       end
     else
       EditText1.AppendLn('Error...');

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jmpessoa · 2024-05-16 01:45

Hi, Alcatiz!

TMySQL57ConnectionBridge  fail to connect.....  but I can't fix it.
Can you help?

----------------------------------------------------------------------
Alcatiz · 2024-05-20 08:22

Just with tiny changes in the constructor and without allocating any
transaction in the Connect() method, I could execute some queries on
my database. 

Here's my component version (I added error codes but they are
certainly useless):
Code: Pascal  [Select][+][-]window.onload = function(){var x1 =
document.getElementById("main_content_section"); if (x1) { var x =
document.getElementsByClassName("geshi");for (var i = 0; i unit
MySQLAndroidConnection; {$mode delphi} interface uses  Classes,
SysUtils, LResources,  SQLDB, DB, MySQL57Conn; type   {
TMySQL57ConnectionBridgeError }   TMySQL57ConnectionBridgeError =
(err_NoError, err_CreateSQLConnection, err_CreateSQLTransaction,
err_CreateSQLQuery);   { TMySQL57ConnectionBridge }  
TMySQL57ConnectionBridge = class(TComponent)  private   
FDataBaseName: String;    FHostName: String;    FPort: Integer;   
FPassword: String;    FUserName: String;    FError:
TMySQL57ConnectionBridgeError;    procedure SetDataBaseName(AValue:
String);    procedure SetHostName(AValue: String);    procedure
SetPassword(AValue: String);    procedure SetPort(AValue: Integer);  
procedure SetUserName(AValue: String);  public    MySQL57Connection:
TMySQL57Connection;    SQLQuery: TSQLQuery;    SQLTransaction:
TSQLTransaction;    constructor Create(AOwner: TComponent); override; 
  destructor Destroy; override;    function Connect: Boolean; 
published    property DataBaseName: String read FDataBaseName write
SetDataBaseName;    property HostName: String read FHostName write
SetHostName;    property Port: Integer read FPort write SetPort;   
property Password: String read FPassword write SetPassword;   
property UserName: String read FUserName write SetUserName;   
property Error: TMySQL57ConnectionBridgeError read FError; 
end; procedure Register; implementation procedure Register;begin  {$I
mysqlandroidconnection_icon.lrs}  RegisterComponents('FCL Bridges',
[TMySQL57ConnectionBridge]);end; { TMySQL57ConnectionBridge
} procedure TMySQL57ConnectionBridge.SetDataBaseName(AValue:
String);begin  if FDataBaseName = AValue then Exit;  FDataBaseName :=
AValue;end; procedure TMySQL57ConnectionBridge.SetHostName(AValue:
String);begin  if FHostName = AValue then Exit;  FHostName :=
AValue;end; procedure TMySQL57ConnectionBridge.SetPassword(AValue:
String);begin  if FPassword = AValue then Exit;  FPassword :=
AValue;end; procedure TMySQL57ConnectionBridge.SetPort(AValue:
Integer);begin  if FPort = AValue then Exit;  FPort :=
AValue;end; procedure TMySQL57ConnectionBridge.SetUserName(AValue:
String);begin  if FUserName = AValue then Exit;  FUserName :=
AValue;end; constructor TMySQL57ConnectionBridge.Create(AOwner:
TComponent);(* Allocates SQLDB components *)begin  inherited
Create(AOwner);  FError := err_NoError;  try    MySQL57Connection :=
TMySQL57Connection.Create(Nil);   
MySQL57Connection.SkipLibraryVersionCheck := True;  except    FError
:= err_CreateSQLConnection;    Exit;  end;  try    SQLTransaction :=
TSQLTransaction.Create(Nil)  except    FError :=
err_CreateSQLTransaction;    Exit;  end;  try    SQLQuery :=
TSQLQuery.Create(Nil);  except    FError := err_CreateSQLQuery; 
end;end; destructor TMySQL57ConnectionBridge.Destroy;(* Deallocates
SQLDB components *)begin  if Assigned(SQLQuery)     then       begin 
      SQLQuery.Close;         SQLQuery.Free;       end;  if
Assigned(SQLTransaction)     then       begin       
 SQLTransaction.Active := False;         SQLTransaction.Free;     
 end;  if Assigned(MySQL57Connection)     then       begin       
 MySQL57Connection.Connected := False;       
 MySQL57Connection.Free;       end;  inherited Destroy;end; function
TMySQL57ConnectionBridge.Connect: Boolean;(* Tries to connect to
database *)begin  Result := False;  MySQL57Connection.DatabaseName :=
FDataBaseName;  MySQL57Connection.HostName := FHostName; 
MySQL57Connection.Port := FPort;  MySQL57Connection.Password :=
FPassword;  MySQL57Connection.UserName := FUserName; 
MySQL57Connection.Transaction := SQLTransaction; 
MySQL57Connection.CharSet := 'UTF8';  SQLQuery.DataBase :=
MySQL57Connection;  try    MySQL57Connection.Open;   
MySQL57Connection.Connected := True;  except   
MySQL57Connection.Connected := False;  end;  Result :=
MySQL57Connection.Connected;end; end.
And this code worked:
Code: Pascal  [Select][+][-]window.onload = function(){var x1 =
document.getElementById("main_content_section"); if (x1) { var x =
document.getElementsByClassName("geshi");for (var i = 0; i procedure
TAndroidModule1.btnConnectClick(Sender: TObject);(* Connection to the
database *)begin  EditText1.Append('Creation result: ');  case
MySQLAndroidConnection1.Error of    err_NoError:
EditText1.AppendLn('no error');    err_CreateSQLConnection:
EditText1.AppendLn('err_CreateSQLConnection');   
err_CreateSQLTransaction:
EditText1.AppendLn('err_CreateSQLTransaction';    err_CreateSQLQuery:
EditText1.AppendLn('err_CreateSQLQuery');  end; 
MySQLAndroidConnection1.HostName := '192.168.1.40'; 
MySQLAndroidConnection1.Port := 3306; 
MySQLAndroidConnection1.DatabaseName := 'xxxxxxx'; 
MySQLAndroidConnection1.UserName := 'yyyyyyy'; 
MySQLAndroidConnection1.Password := 'zzzzzzz';  if
MySQLAndroidConnection1.Connect     then     
 EditText1.AppendLn('Connected!');     else     
 EditText1.AppendLn('Error...');end; procedure
TAndroidModule1.btnQueryClick(Sender: TObject);(* Lists a table
*)begin  MySQLAndroidConnection1.SQLQuery.Close; 
MySQLAndroidConnection1.SQLQuery.SQL.Text := 'SELECT * FROM
T_CATEGORIES;';  MySQLAndroidConnection1.SQLQuery.Open; 
MySQLAndroidConnection1.SQLQuery.Last;  EditText1.AppendLn('Number of
records: ' + IntToStr(MySQLAndroidConnection1.SQLQuery.RecordCount)); 
MySQLAndroidConnection1.SQLQuery.First;  while not
MySQLAndroidConnection1.SQLQuery.EOF do    begin      EditText1.Append
Ln(MySQLAndroidConnection1.SQLQuery.FieldByName('F_CATEGORYNAME').AsSt
ring);      MySQLAndroidConnection1.SQLQuery.Next;    end;end;