Im a new user of stack overflow. I have a big project coming up and i keep getting the same error. I’m trying to load data into my database and no matter how many times I try or what I change I still get the same errors. I have labled nessarry variables, tried tbl().Edit and tbl().Insert inside, outside of my loops and in the case statement but i still seem to be getting the same error.
sPlayer1,sPlayer2, iScore1,iScore2 are global variables.
`
procedure TfrmInvigilator.btnSubmitClick(Sender: TObject);
Var
i, j, iRound: Integer;
begin
sPlayer1 := cmbName1.Text; // Assigning values to variables for cmbPlayers
sPlayer2 := cmbName2.Text;
iScore1 := sedScore1.Value; // Assigning values to variables for sedScores
iScore2 := sedScore2.Value;
iRound := cmbRound.ItemIndex; // Assigning values to variable for cmbRound
if (cmbName1.ItemIndex = -1) then
// Displays show message if cbmName1 is blank
begin
ShowMessage('Please select player name');
end
else
begin // If cbmName1 is not blank then:
i := pos(' ', sPlayer1); // Find position of ' ' in cbmName1.Text
sPlayer1 := Copy(sPlayer1, 1, i - 1); // sPlayer1 := Name of player
dmChess.tblPlayerInfo.Locate('Name', sPlayer1, []); // Locates Name in table
Num1 := dmChess.tblPlayerInfo['ID']; // Retrives ID of player
with dmChess do
begin
tblScoreboard.First;
while NOT tblScoreboard.EOF do
begin
tblScoreboard.Locate('ID', Num1, []);
case iRound of
0:
tblScoreboard['Round 1A'] := iScore1;
1:
tblScoreboard['Round 1B'] := iScore1;
2:
tblScoreboard['Round 1C'] := iScore1;
3:
tblScoreboard['Round 1D'] := iScore1;
4:
tblScoreboard['Round 2'] := iScore1;
5:
tblScoreboard['Semi-Final'] := iScore1;
6:
tblScoreboard['Final'] := iScore1;
end;
tblScoreboard.Post;
end;
end;
end;
if (cmbName2.ItemIndex = -1) then
// Displays show message if cbmName2 is blank
begin
ShowMessage('Please slecet player name');
end
else
begin // If cbmName2 is not blank then:
j := pos(' ', sPlayer2); // Find position of ' ' in cbmName2.Text
sPlayer2 := Copy(sPlayer2, 1, j - 1); // sPlayer2 := Name of player
dmChess.tblPlayerInfo.Locate('Name', sPlayer2, []); // Locates Name in table
Num1 := dmChess.tblPlayerInfo['ID']; // Retrives ID of player
end;
end;
`
You can't just set a new value in a DataSet field (table or query), the DataSet must know that you want to change the current record or insert a new one. An exception tells you this. How to solve: before you make changes to any field in the dataset, you need to set the desired mode. DataSet.edit; - to edit the current record, DataSet.Insert - to insert a new record in the current location, DataSet.Append - to add a new record to the end. For this code snippet, add the line tblScoreboard.Edit; after the line tblScoreboard.Locate('ID', Num1, []);
DataSet.Post – save current changes into record and change DataSet mode back to Browsing
Related
I have the following Scenario: In a textfile (justin#us883) the program must extract the password - us883 check if the password typed in is correct to the one in the list and then make a button visible to enter program: Code that is not working:
var
textf:textfile;
oneline,spass,scheck :string;
place,i,icount :integer;
Arrpass : array[1..Maxnames] of string;
begin
scheck := edtpass.Text;
assignfile(textf,'Userlist.txt');
reset(textf);
if fileExists('Userlist.txt')= false then
exit;
while not eof(textf) do
begin
Readln(textf, oneline);
place := pos('#',oneline);
delete(oneline,1,place);
spass := copy(oneline,1,place-1); // get the us883
Arrpass[i] := spass;
for i := Low(Arrpass) to High(Arrpass) do
if Arrpass[i] = spass then
begin
btnenter.Visible := true
end
else
btnenter.Visible := False;
Showmessage('Wrong Password');
end;
closefile(textf);
end;
Maybe you want to do it more delphi like:
var
list : TStringList;
user, password : String;
i : Integer;
begin
user := 'user1';
if fileExists('Userlist.txt')= false then exit;
list := TStringList.create();
list.NameValueSeparator := '#';
list.LoadFromFile('Userlist.txt');
i := list.IndexOfName(user);
if i >=0 then begin
password := list.Values[user];
// check password
end;
Issue 1:
place := pos('#',oneline);
delete(oneline,1,place);
spass := copy(oneline,1,place-1); // get the us883
The third line uses position of # that is not more actual (after deletion).
If you don't expect more symbols after password, just use
spass := oneline;
Issue 2:
How Arrpass array sould be filled?
This line Arrpass[i] := spass; uses uninitialized variable i. And what is a logic to compare just inserted value with itself? Perhaps you want to fill ArrPass before text reading.
Issue 3:
It is worth to check if fileExists before file handling.
I'm creating a basic concept of a music player using Pascal, but I'm struggling to display the albums inside it. The error I got says "(134, 29) Error: Can't read or write variables of this type". I'm assuming it's saying that because I'm using an array within an array, and it's having a hard time displaying both at the same time (although I only want it to display the albums, not the tracks as well).
Here's what my code looks like:
function ReadAllTrack(prompt: String): Tracks;
var
i: Integer;
trackArray: Array of Track;
trackCount: Integer;
begin
WriteLn(prompt);
trackCount := ReadIntegerGreaterThan1('Please enter the number of tracks you would like to add: ');
Setlength(trackArray, trackCount);
for i := 0 to trackCount - 1 do
begin
WriteLn('Enter the details for your track:');
trackArray[i] := ReadTrack();
end;
result := trackArray;
end;
function ReadAlbum(): Album;
begin
result.albumName := ReadString('Album name: ');
result.artistName := ReadString('Artist name: ');
result.albumGenre := ReadGenre('Genre:');
result.trackCollection := ReadAllTrack('Track Collection:');
end;
function ReadAllAlbums(): Albums;
var
i: Integer;
albumArray: Array of Album;
albumCount: Integer;
begin
albumCount := ReadIntegerGreaterThan1('Please enter the number of albums you would like to add: ');
Setlength(albumArray, albumCount);
for i := 0 to albumCount - 1 do
begin
WriteLn('Enter the details for your album:');
albumArray[i] := ReadAlbum();
end;
result := albumArray;
end;
procedure DisplayAlbumOptions(listOfAllAlbums: Albums);
var
userInput: Integer;
begin
WriteLn('1. Display all albums');
WriteLn('2. Display all albums for a genre');
userInput := ReadIntegerRange('Please enter a number (1, 2) to select: ', 1, 2);
case userInput of
1: WriteLn(listOfAllAlbums); //Error: Can't read or write variables of this type
end;
end;
Basically what this does is it will ask the user showing 5 options:
1. Add albums
2. Display albums
etc
If the user selects 1, the program will ask the user to input the number of albums they want to input. Then for each album it'll ask them to enter the details, and then the tracks.
Then if the user selects 2, the program will ask the user to choose either display every single album there is, or display all albums for a single genre (I'll be working on this one after solving this problem). At first I thought it would be just as simple as WriteLn(TheAlbumArray); but turns out it was more complicated than I thought because I don't think it's possible for the program to display it this way. I tried separating the albums and tracks so that it would only display the albums when I use WriteLn(TheAlbumArray); but it wasn't possible because the tracks still have to be "inside" the album so that when I display the albums and select one of them, it would then display the tracks....
Any help or suggestion for this and/or the second will be much appreciated ^^
Your original question contained a lot of superfluous detail. After the edit, you removed the type declarations, but kept much of the superfluous detail.
However, it is possible to discern the problem you are passing an array of record to Writeln. The Writeln function can accept only certain simple types as arguments, e.g. strings, numerical types, boolean. You certainly cannot pass an array to Writeln. You must iterate over the array and process each member individually.
So you might try
for i := low(listOfAllAlbums) to high(listOfAllAlbums) do
WriteLn(listOfAllAlbums[i]);
But that does not work either, because listOfAllAlbums[i] is a record, and a record is a compound type which cannot be passed to Writeln. So you need to process the record separately. If you want to display just the title, then you write:
for i := low(listOfAllAlbums) to high(listOfAllAlbums) do
WriteLn(listOfAllAlbums[i].albumName);
If you want to print the track titles too then you need to iterate over the array contained in the record.
for i := low(listOfAllAlbums) to high(listOfAllAlbums) do
begin
WriteLn(listOfAllAlbums[i].albumName);
for j := low(trackCollection) to high(trackCollection) do
WriteLn(listOfAllAlbums[i].trackCollection[j]);
end;
It is impossible to use composite types (arrays, records, ...) in Read[ln] and Write[ln] procedures.
To make your code more transparent you could to create type helper for your array(s) and use well-known AsString property. Here is example for simple array of Integer:
program foo;
{$mode objfpc}{$H+}
{$modeswitch typehelpers}
uses
Classes, SysUtils;
type
TMyArray = array of Integer;
TMyArrayHelper = type helper for TMyArray
private
function GetAsString: string;
procedure SetAsString(const AValue: string);
public
property AsString: string read GetAsString write SetAsString;
end;
function TMyArrayHelper.GetAsString: string;
var
i: Integer;
begin
Result := '';
for i in Self do
begin
if Result <> '' then
Result := Result + ', ';
Result := Result + IntToStr(i);
end;
Result := '[' + Result + ']';
end;
// Relatively simple parser
// Fill free to implement ones for your array type
procedure TMyArrayHelper.SetAsString(const AValue: string);
var
tmp, s: string;
items: TStringArray;
i: Integer;
begin
tmp := Trim(AValue);
if not (tmp.StartsWith('[') and tmp.EndsWith(']')) then
raise Exception.CreateFmt('Invalid array literal format: "%s"', [tmp]);
tmp := tmp.Trim(['[', ']']);
items := tmp.Split([',']);
for s in items do
try
StrToInt(s);
except
on e: Exception do
raise Exception.CreateFmt('Invalid integer literal: "%s"', [s]);
end;
SetLength(Self, Length(items));
for i := 0 to Length(items) - 1 do
Self[i] := StrToInt(items[i]);
end;
var
a1, a2: TMyArray;
begin
a1.AsString := '[1,2,3,5]';
Writeln('a1 = ', a1.AsString);
a2.AsString := a1.AsString;
a2[1] := 999;
Writeln('a2 = ', a2.AsString);
end.
Helper types in FreePascal
TStringHelper in SysUtils unit
Let's say I have a string like this :
string1 := 'me,email1,you,email2,him,email3,them,email4';
To turn this into an array of string I simply do :
array1 := SplitString(string1,',');
This works fine.
But then, I get an array like :
array1[0] -> me
array1[1] -> email1
array1[2] -> you
array1[3] -> email2
array1[4] -> him
array1[5] -> email3
array1[6] -> them
array1[7] -> email4
I've searched a long time how to insert into SQLIte with this but there is no using
for i:= 0 to length(array1) -1
SQLExecute('INSERT INTO table(name,email) VALUES("'+array1[i]+'","'+array1[i+1]+'"');
because index 0 will be inserted as name with index 1 as email, but on the next turn, index 1 will be inserted as name with index 2 as email, when index 1 is en email, and index 2 a name... do you see the problem ?
I thought about re-spliting the first array into a second one by changing the initial string format into :
string1 := 'me-email1,you-email2,him-email3,them-email4';
to split a first time on the ' and a second time on the -, to get a 2 dimensional array, but seems this concept is over my knowledge at the moment :)
Just for the record, the Delphi RAD I'm using is quite recent, and only a few functions / tools are available at the moment.
How would you insert into sql ? Would you keep the original String format, or change it to get a 2 dimensional array ?
Iterate in pairs:
for i := 0 to length(array1) div 2 - 1 do
SQLExecute('INSERT INTO table(name,email) VALUES("'+array1[i*2]+'","'+array1[i*2+1]+'"');
You just should not use per-INSERT FOR-loop here.
It is not suited for it and it is dangerous if your string would have 3 or 7 or any other odd number of elements.
Also splicing random data right into the SQL command is extremely unreliable and fragile. http://bobby-tables.com/
You should either use a WHILE-loop with a sliding fetcher or tick-tock (finite state machine) swinging in one-per-string FOR-loop.
var q: TQuery;
// some Query-component of any library,
// including DBX, AnyDAC/ FireDAC mORMot or any other library you would use
var sa_OK, sa_err1, sa_err2: TArray<string>;
// common preparations for both methods
q.ParamCheck := True;
q.SQL.Text := 'INSERT INTO table(name,email) VALUES( :PName, :PMail )';
q.Prepared := True;
sa_OK := TArray<string>.Create( 'me','email1','you','email2','him','email3','them','email4');
// eeeaaasy example
sa_err1 := TArray<string>.Create( 'me','email1','you','email2','him');
// check this out-of-sync error too - it can happen! you should be pre-aware!
sa_err2 := TArray<string>.Create( 'Sarah O''Connor','email1','"Bobby F. Kennedy"','email2','him'#0'again','email3');
// not the letters you expected - but they can come too
Procedure Method1_Fetcher( const sa: array of string );
var i: integer;
s: string;
function Fetched: Boolean;
begin
Result := i <= High(sa);
if Result then begin
s := sa[i];
Inc(i);
end;
end;
Begin
i := Low(sa);
while true do begin
if not Fetched then break;
q.Params[1].AsWideString := s;
if not Fetched then break;
q.Params[2].AsWideString := s;
// ...you can easily add more parameters for more columns
// if not Fetched then break;
// q.Params[3].Value := s;
// ... or you can make a loop
// FOR j := 0 to q.Params.Count - 1 DO ... q.Params[j] :=...
// only executing insert if ALL the columns were filled
q.ExecSQL;
end;
q.Transaction.CommitWork;
End;
Procedure Method2_TickTock( const sa: array of string );
var i, FSM: integer;
Begin
FSM := 0;
for i := Low(sa) to High(sa) do begin
if FSM = 0 then begin
q.ParamByName('PName').AsWideString := sa[i];
FSM := 1; // next mode of tick-tock
Continue;
end;
if FSM = 1 then begin
q.ParamByName('PMail').AsWideString := sa[i];
q.ExecSQL;
// only executing insert after the last column was filled
FSM := 0; // next mode of tick-tock
Continue;
end;
/// would only come here if we made some mistake above
/// and FSM got impossible value - so no "Continue" was executed
/// show error and exit
raise EInvalidOperation.CreateFmt('FSM = %d', [FSM]);
end;
q.Transaction.CommitWork;
End;
Procedure Method3_SimplifiedFSM( const sa: array of string );
// this method is actually are streamlined method #2
// it can be made because all our steps are TOTALLY identical
// ( sans optional insert execution )
var i, FSM: integer;
Begin
FSM := 0;
for i := Low(sa) to High(sa) do begin
q.Params[ FSM ].AsWideString := sa[i];
Inc( FSM );
if FSM >= q.Params.Count then begin
q.ExecSQL; // only after (if ) last of all columns filled!
FSM := 0;
end;
end;
q.Transaction.CommitWork;
End;
Now you can debug calls like Method1(sa_OK) or Method2(sa_err1) and see how it is working and how it deals with errors
I'm trying to change the visible text (value) of a DBLookupComboBox, using :
DBLookupComboBox1.KeyValue:=S;
and
DBLookupComboBox2.KeyValue:=X;
If the KeyValue and S are strings, then everything works fine, and I can set the value.
But when the KeyValue is an integer/Int64 (UID in the DB), and X is an Int64 variable - it doesn't work, and nothing changes.
So for an example, i need to set "Amsterdam" in DBLookupComboBox1, and 1500 in DBLookupComboBox2.
"Amsterdam" from the "City" field of the users, and 1500 as the UID.
What am I doing wrong please?
Thanks
This code is Important for you:
lkcbbArzSource.KeyValue:=2;//c(or another number);
lkcbbArzSource is a dbLookupComboBox object and you can insert only a number in this!why? because is numeric and another side of that there is a field that show a text or String of that numeric in combo.
in below sample code you can see a dbLookupComboBox how to menage and fill with Data-set and add in a grid :
rzSource.Enabled:= True;
lkcbbArzSource.Font.Size:=8;
lkcbbArzSource.Tag := V_Counter;
lkcbbArzSource.Visible:= True;
lkcbbArzSource.Enabled:= True;
lkcbbArzSource.Font.Name:='tahoma';
lkcbbArzSource.ListSource := myDsrSource;
lkcbbArzSource.KeyField := 'Code';
lkcbbArzSource.ListField := 'Des';
lkcbbArzSource.KeyValue:= IntToStr(FieldByName('P_ARZSOURCE').AsInteger);
lkcbbArzSource.OnChange := myBicLookUpChange;
SGrid2.Objects[look_col,lkcbbArzSource.Tag]:= lkcbbArzSource;
SGRID2.Objects[look_col,V_Counter] := nil;
Setting the KeyValue calls the SetKeyValue of the TDBLookupControl which in Delphi 7 appears as:
procedure TDBLookupControl.SetKeyValue(const Value: Variant);
begin
if not VarEquals(FKeyValue, Value) then
begin
FKeyValue := Value;
KeyValueChanged;
end;
end;
procedure TDBLookupComboBox.KeyValueChanged;
begin
if FLookupMode then
begin
FText := FDataField.DisplayText;
FAlignment := FDataField.Alignment;
end else
if ListActive and LocateKey then
begin
FText := FListField.DisplayText;
FAlignment := FListField.Alignment;
end else
begin
FText := '';
FAlignment := taLeftJustify;
end;
Invalidate;
end;
As you can see, your variable x is used as part of a LocateKey.
function TDBLookupControl.LocateKey: Boolean;
var
KeySave: Variant;
begin
Result := False;
try
KeySave := FKeyValue;
if not VarIsNull(FKeyValue) and FListLink.DataSet.Active and
FListLink.DataSet.Locate(FKeyFieldName, FKeyValue, []) then // << ---here
begin
Result := True;
FKeyValue := KeySave;
end;
except
end;
end;
Stepping into these procedures and functions should help you to debug your issue. All are located in the DbCtrls unit..
I have used this and solved my problem.
Use this lines of code at Form1.OnShow :
DBLookupComboBox1.ListSource.DataSet.Locate('City', 'Amsterdam', []);
DBLookupComboBox1.ListSource.DataSet.FieldByName(DBLookupComboBox1.KeyField).Value;
DBLookupComboBox2.ListSource.DataSet.Locate('UID', '1500', []);
DBLookupComboBox2.ListSource.DataSet.FieldByName(DBLookupComboBox2.KeyField).Value;
I have sporadic problems (access violation in unit System).
Application is running 24 x 7 and it happens one - two times in a week.
I have a procedure with local string array, and I found there are cases I assign non initialised array member to string variable like in code below.
Could it be a reason for access violation?
procedure tform1.DoSomething;
var
sarr: array [1..4] of String;
s: String;
begin
sarr[1] := 'aaaa';
sarr[2] := 'bbbb';
s := sarr[3]; // Can I get here an access violation???
end;
Real function code below
exception happens when obj.opcode = cmdp_done
function is called from thread message queue. obj is created in another thread, and
sent in PostThreadMessage as msg.lparam
procedure ORTR_ProcessFiscalResponse(obj: TDataForOrpak);
const
maxdim = 4;
var
s: array [1..maxdim] of String;
i, n, fiscalNr, statusToSend: Integer;
sql, pdf, ortrName, docType, rut: String;
ortr: TCustomizedOrtr;
oFiscal: TFiscalDevice;
fpds: TFPDeviceState;
begin
try
case obj.opcode of
cmdp_status: N := 3;
cmdp_done: N := 2;
plcl_docissued: N := 4;
plcl_docfailed: N := 1;
else
Exit;
end;
for i:=1 to n do
s[i] := GetTerm(obj.ident, i, ';');
if s[1] = '' then
Exit;
statusToSend := 0;
ortrName := GetTerm(s[1], 1, '+');
fiscalNr := StrToIntDef(GetTerm(s[1]+'+', 2, '+'), 999999);
docType := s[3];
rut := s[4];
ortr := TCustomizedOrtr.GetTerminalByName(ortrName) as TCustomizedOrtr;
if ortr = nil then
Exit;
if (ortr.FPState = fps_idle) or (ortr.fiscalNr <> fiscalNr) then begin
if (StrToIntDef(s[2], 0) <> 0) and (obj.opcode = cmdp_done) then
fiscal_Confirm(obj.otherdevname, obj.ident);
if obj.opcode = plcl_docissued then begin
try
PLCL_SetDocState(s[1], rut, false, StrToInt(s[2]), StrToInt(docType));
except
AddToLogFile('*** PLCL_SetDocState', log_exceptions);
end;
end;
Exit;
end;
oFiscal := fiscal_Assigned(ortr.ctlPump.PumpID) as TFiscalDevice;
case obj.opcode of
plcl_docissued:
begin
ortr.authData.ECRReceiptNr := s[2];
pdf := StringFromHexPresentation(obj.rawdata);
sql := format(sql_PaperlessAdd, [
ToLocalSQL_DateTime(ortr.ctlPump.FinalTime),
ToLocalSQL_Integer(ortr.ctlPump.PumpID),
ToLocalSQL_String(pdf)]);
try
UpdateLocalDB(sql);
except
AddToLogFile('*** PL save pdf', log_exceptions);
end;
try
PLCL_SetDocState(s[1], rut, true, StrToInt(s[2]), StrToInt(docType));
except
AddToLogFile('*** PLCL_SetDocState', log_exceptions);
end;
ortr.FPState := fps_idle;
ortr.currStage := TTextIndexType(0);
ortr.currStage := tivirt_towelcome; // VADIM
ExternalProcessPumpState(ortr.authData.gsPump.PumpID);
end;
plcl_docfailed:
ortr.FPState := fps_plerror;
cmdp_status:
begin
ortr.FPError := StrToIntDef(s[3], 0);
fpds := TFPDeviceState(StrToIntDef(s[2], 0));
ortr.FPState := fpds;
if (fpds in [fps_nocomm, fps_error]) and (ortr.fiscalMode = 1) and
(ortr.authData = nil) and (ortr.fiscalNr < 0) then
SpecialInterface.SendFiscalNrToPromax(-ortr.fiscalNr, '0');
case fpds of
fps_nopaper: statusToSend := wph_prnpaperout;
fps_nocomm: statusToSend := wph_prncommfailure;
fps_error: statusToSend := wph_prngenericfailure;
end;
end;
cmdp_done:
begin
if ortr.fiscalMode = 1 then begin
if ortr.authData = nil then begin // DRY GOOD
SpecialInterface.SendFiscalNrToPromax(-fiscalNr, s[2]);
end
else begin
ortr.authData.ECRReceiptNr := s[2];
ExternalProcessPumpState(ortr.authData.gsPump.PumpID);
end
end;
if StrToIntDef(s[2], 0) <> 0 then
fiscal_Confirm(obj.otherdevname, obj.ident);
statusToSend := wph_prnidle;
ortr.FPState := fps_idle;
ortr.currStage := ti_takereceipt;
end;
end;
if (statusToSend <> 0) and (oFiscal <> nil) then
PostNonVisualCommand(nv_devicestate, statusToSend, Integer(oFiscal));
finally
obj.free;
end;
end;
Your initial piece of code, the tform1.DoSomething routine, is unable of producing an access violation:
For the static array variable sarr, memory is allocated for all its elements.
The string variable s, as well as the elements in sarr, are automatically initialized to empty. 1
Thus you are simply assigning an empty string, and s remains empty.
Concerning your actual code, assuming that it does produce the access violation, my guess would be that:
the obj parameter still refers to an already destroyed object,
that obj.opcode reads an invalid piece of memory, but since it is compared to an numerical value, will pass,
that Exit is called in de case else clause, and
that obj.Free fails in the finally clause.
1 All string variables are initilized to empty, except string function results:
If the function exits without assigning a value to Result or the function name, then the function's return value is undefined.
The missing compiler warning is still a bug.