C / C++ / MFC

17-Sep-01 3:55

With thanks to Michael Butler, I've figured out where my ATL project is dying. I have added four fields to my database. They are being populated correctly. Previously, retrieved my values like this:

	_RecordsetPtr records = NULL;
	 records.CreateInstance(__uuidof(Recordset));

	try
	{
		records->CursorType = adOpenStatic;
		records->CursorLocation = adUseClient;
		records->Open("SELECT * FROM FileDatabase",
		_variant_t((IDispatch*)m_Connection, true), adOpenKeyset, adLockOptimistic, 
		adCmdUnknown);
	}
	catch(...)//_com_error & e)
	{
//		MessageBox(NULL, e.ErrorMessage(), "", 0);
	}

	records->MoveFirst();

	vector<ISAFileEntry*> vecDatabase;
	
	do
	{
        	CComObject<CSAFileEntry>* pFileEntry = NULL;

		CComObject<CSAFileEntry>::CreateInstance(&pFileEntry);

		if (pFileEntry)
		{
			FieldsPtr spFields = records->GetFields();

			string s = (bstr_t) spFields->Item["FileName"]->Value;
			for (string::iterator it = s.begin(); it != s.end(); ++it)
				 if (*it == '?') *it = '\'';
			pFileEntry->m_FileName = s.c_str();
			pFileEntry->m_FileLength = spFields->Item["FileLength"];
			pFileEntry->m_DownloadCount = spFields->Item["TimesDownloaded"];
			pFileEntry->m_LastModified = spFields->Item["LastModified"];

but since adding four more fields, I find all my numeric values are being read a 0, although Access show me real values have been stored.

Changing to this:

string s = (bstr_t) spFields->Item["FileName"]->Value;
for (string::iterator it = s.begin(); it != s.end(); ++it)
     if (*it == '?') *it = '\'';
pFileEntry->m_FileName = s.c_str();
pFileEntry->m_FileLength = spFields->Item["FileLength"]->Value;
pFileEntry->m_DownloadCount = spFields->Item["TimesDownloaded"]->Value;
pFileEntry->m_LastModified = spFields->Item["LastModified"]->Value;
pFileEntry->m_Frames = spFields->Item["Frames"];
pFileEntry->m_Seconds = spFields->Item["Seconds"];
pFileEntry->m_Width = spFields->Item["Width"];
pFileEntry->m_Height = spFields->Item["Height"];

Works for my old values ( I added ->Value to them ), but my new values are still 1, and if I add ->Value to them, it crashes in the first iteration. Can anyone suggest what might be the problem ?

Christian

As I learn the innermost secrets of the around me, they reward me in many ways to keep quiet.

Men with pierced ears are better prepared for marriage. They've experienced pain and bought Jewellery.

Michael P Butler17-Sep-01 4:01

17-Sep-01 4:01

Which "field" does it crash on? Do the names match the field names in the database? Do they all cause the problem or can you rem some out and it works?

I'm old fashioned and access my fields by position rather than name

variant_t vt;

vt = m_pRecordset->Fields->GetItem(variant_t((short)4))->GetValue();

Michael

Christian Graus17-Sep-01 4:06

17-Sep-01 4:06

Any of the four I've added, I've tried them all. Yes, the fields are spelled right, I've checked a bajillion times.

The following code is how the information got put into the database in the first place, and it's there and fine.

spFields->Item["FileName"]->Value = (bstr_t) temp;
spFields->Item["FilePath"]->Value = (bstr_t) bstrPath;
spFields->Item["FileLength"]->Value = (*it)->m_FileLength;
spFields->Item["LastModified"]->Value = (*it)->m_LastModified;
spFields->Item["TimesDownloaded"]->Value = (long)0;
spFields->Item["Frames"]->Value = lFrames;
spFields->Item["Seconds"]->Value = lSeconds;
spFields->Item["Width"]->Value = Width;
spFields->Item["Height"]->Value = Height;

What I don't get is how come it crashes when I add ->Value, otherwise it just returns 1 ? I mean, I know ADO crashes at the drop of a pin and gives you no debugging help, but still.

I don't know how to access by position ( and I'd really like to make this work both ways if I can ), because the whole point of this project is to learn more ATL and some ADO. Please ellucidate.

Christian

As I learn the innermost secrets of the around me, they reward me in many ways to keep quiet.

Men with pierced ears are better prepared for marriage. They've experienced pain and bought Jewellery.

Michael P Butler17-Sep-01 4:27

17-Sep-01 4:27

Well, ADO isn't something I've done a lot with so it could be a case of the blind leading the blind Smile | :)

the spFields collection has a Count property

long nRecordCount = pRst->Fields->Count

how many fields does it say your recordset has?

you could try looping through a record like below and see if it displays all your data (I've hacked this from one of the platform sdk samples)

FieldPtr       pFld     = NULL;
_variant_t    vIndex;

pRst->MoveFirst();
long limit = 0;
limit = ((pRst->Fields->Count) - 1);
for (short iIndex = 0; iIndex <= limit; iIndex++)
{
  vIndex = iIndex;
  pFld = pRst->Fields->GetItem(&vIndex);
  printf("Field %d : Name =  '%s', ", iIndex,
         (LPCSTR)pFld->GetName());
  _variant_t FldVal = pFld->GetValue();  

}

Christian Graus17-Sep-01 4:27

17-Sep-01 4:27

I've solved it, thanks. I read my recordset in like this:

	_RecordsetPtr records = NULL;
	 records.CreateInstance(__uuidof(Recordset));

	try
	{
		records->CursorType = adOpenStatic;
		records->CursorLocation = adUseClient;
		records->Open("SELECT * FROM FileDatabase",
		_variant_t((IDispatch*)m_Connection, true), adOpenKeyset, adLockOptimistic, 
		adCmdUnknown);
	}
	catch(...)//_com_error & e)
	{
//		MessageBox(NULL, e.ErrorMessage(), "", 0);
	}

and if the database file in empty it crashes big time. Do you know why that might be ? Anyhow, as a result the first record is a dummy record. I needed to reread some ADO stuff to get clear in my mind what I was manipulating, then I checked the VARIANT coming back from ->Value and found it was VT_NULL, because when I added those four fields, I didn't add dummy values for the dummy record.

I'd love your insight on my empty DB problem though, and on accessing values by position, if you don't mind.

Thanks for the help.

Christian

As I learn the innermost secrets of the around me, they reward me in many ways to keep quiet.

Men with pierced ears are better prepared for marriage. They've experienced pain and bought Jewellery.

Michael P Butler17-Sep-01 4:35

17-Sep-01 4:35

Not sure about the empty DB at the moment. The link below is the sample I used for learning how to access fields from a database. It uses position rather than field name.

http://msdn.microsoft.com/library/default.asp?url=/library/en-us/ado270/htm/mdmthitemxvc.asp

Michael Smile | :)

Jeremy Pullicino17-Sep-01 5:29

Jeremy Pullicino

17-Sep-01 5:29

You should put try...catch blocks around your spFields->Item["field"]; statements because this call could throw exceptions. The exception you find might give you an indication on why it is failing.

Jeremy.

Christian Graus17-Sep-01 13:00

17-Sep-01 13:00

Thanks - I came to that conclusion last night ( I'd actually taken a book to bed, and was thinking about what I'd read when I bounded out of bed to solve the problem ). However, in my experience the exception for ADO is *always* unknown error and ADO flags don't offer much help either. I've grown to hate ADO with every failed attempt to pass perfectly valid SQL to it.

Christian

As I learn the innermost secrets of the around me, they reward me in many ways to keep quiet.

Men with pierced ears are better prepared for marriage. They've experienced pain and bought Jewellery.

Absolute bloody ATL hell

Christian Graus17-Sep-01 2:12

17-Sep-01 2:12

I have an IEnumXXX class, and another class which contains my database methods. Tonight I removed some unwanted methods from the database class based on help I got earlier today - no problems.

However, I started work on my MFC client for the database and discovered that now when I get any numeric data from my enumeration, the values are all garbage. Everything comes out with a value of 1. The database is fine, and the program used to return real values. Can anyone suggest what may have gone wrong ? I deleted the methods from the idl, .h and .cpp files, renumbered the methods so they ran from 1 with no gaps and rebuilt all. I had no errors or warnings.

// SAFileEntry.h : Declaration of the CSAFileEntry

#ifndef __SAFILEENTRY_H_
#define __SAFILEENTRY_H_

#include "resource.h"       // main symbols

/////////////////////////////////////////////////////////////////////////////
// CSAFileEntry
class ATL_NO_VTABLE CSAFileEntry : 
	public CComObjectRootEx<CComSingleThreadModel>,
	public CComCoClass<CSAFileEntry, &CLSID_SAFileEntry>,
	public IDispatchImpl<ISAFileEntry, &IID_ISAFileEntry, &LIBID_SADATABASELib>
{
public:
	CSAFileEntry()
	{
	}

	CComBSTR m_FileName;
	CComBSTR m_FilePath;
	long     m_FileLength;
	long     m_DownloadCount;
	long     m_LastModified;
	long     m_Frames;
	long     m_Seconds;
	long     m_Width;
	long     m_Height;


DECLARE_REGISTRY_RESOURCEID(IDR_SAFILEENTRY)

DECLARE_PROTECT_FINAL_CONSTRUCT()

BEGIN_COM_MAP(CSAFileEntry)
	COM_INTERFACE_ENTRY(ISAFileEntry)
	COM_INTERFACE_ENTRY(IDispatch)
END_COM_MAP()

// ISAFileEntry
public:
	STDMETHOD(get_Height)(/*[out, retval]*/ long *pVal);
	STDMETHOD(get_Width)(/*[out, retval]*/ long *pVal);
	STDMETHOD(get_Seconds)(/*[out, retval]*/ long *pVal);
	STDMETHOD(get_Frames)(/*[out, retval]*/ long *pVal);
	STDMETHOD(get_Modified)(/*[out, retval]*/ long *pVal);
	STDMETHOD(get_DownloadCount)(/*[out, retval]*/ short *pVal);
	STDMETHOD(get_FileLength)(/*[out, retval]*/ long *pVal);
	STDMETHOD(get_FilePath)(/*[out, retval]*/ BSTR *pVal);
	STDMETHOD(get_FileName)(/*[out, retval]*/ BSTR *pVal);
};

#endif //__SAFILEENTRY_H_

Only get_FilePath and get_FileName are working, and I've traced in to make sure the values in the class are indeed kaput.

Christian

As I learn the innermost secrets of the around me, they reward me in many ways to keep quiet.

Men with pierced ears are better prepared for marriage. They've experienced pain and bought Jewellery.

Michael P Butler17-Sep-01 2:35

17-Sep-01 2:35

What is the code like for functions, get_Height for instance.

I guess it is a simple

(*pVal) = m_Height;

Or are you doing something else?

Michael Smile | :)

Christian Graus17-Sep-01 2:51

17-Sep-01 2:51

That is precisely what my GetHeight function looks like and the thing is, it used to work, but now if I break in the function, m_Height always equals 1. I know from opening it in access that the actual values are fine in the database, but now only the string values come out fine.

Christian

As I learn the innermost secrets of the around me, they reward me in many ways to keep quiet.

Men with pierced ears are better prepared for marriage. They've experienced pain and bought Jewellery.

Michael P Butler17-Sep-01 3:02

17-Sep-01 3:02

What function fills the class variables with data? Does the data go into the class variables okay?

What happens if your initialise m_Height to 255 in the constructor? Does it still give 1?

Michael Smile | :)

Christian Graus17-Sep-01 3:10

17-Sep-01 3:10

If I make it 255 in the constructor, it still comes out as 1. If I make it 255 in the function, it comes out 255. I traced into my function that reads the data:

	try
	{
		records->CursorType = adOpenStatic;
		records->CursorLocation = adUseClient;
		records->Open("SELECT * FROM FileDatabase",
		_variant_t((IDispatch*)m_Connection, true), adOpenKeyset, adLockOptimistic, 
		adCmdUnknown);
	}
	catch(...)//_com_error & e)
	{
//		MessageBox(NULL, e.ErrorMessage(), "", 0);
	}

	records->MoveFirst();

	vector<ISAFileEntry*> vecDatabase;
	
	do
	{
		CComObject<CSAFileEntry>* pFileEntry = NULL;

		CComObject<CSAFileEntry>::CreateInstance(&pFileEntry);

		if (pFileEntry)
		{
			FieldsPtr spFields = records->GetFields();

			string s = (bstr_t) spFields->Item["FileName"]->Value;
			for (string::iterator it = s.begin(); it != s.end(); ++it)
				 if (*it == '?') *it = '\'';
			pFileEntry->m_FileName = s.c_str();
			pFileEntry->m_FileLength = spFields->Item["FileLength"];
			pFileEntry->m_DownloadCount = spFields->Item["TimesDownloaded"];
			pFileEntry->m_LastModified = spFields->Item["LastModified"];
			pFileEntry->m_Width = spFields->Item["Width"];
			pFileEntry->m_Height = spFields->Item["Height"];
			pFileEntry->m_Frames = spFields->Item["Frames"];
			pFileEntry->m_Seconds = spFields->Item["Seconds"];

and when the data comes out of the database and into the pFileEntry, it is already corrupted, they are already all 1's.

Christian

As I learn the innermost secrets of the around me, they reward me in many ways to keep quiet.

Men with pierced ears are better prepared for marriage. They've experienced pain and bought Jewellery.

Michael P Butler17-Sep-01 3:15

17-Sep-01 3:15

I'm not familiar with the database calls so this may be a stab in the dark,

your string is accessed via

string s = (bstr_t) spFields->Item["FileName"]->Value

yet your numbers are dont use the Value variable. Is this right

pFileEntry->m_Height = spFields->Item["Height"];

Michael

Christian Graus17-Sep-01 3:30

Re: Handling Button's Events

17-Sep-01 3:30

Well, how about that ? Thanks so much. I'm half way there now. The File Lengths are loading fine, but the properties I added most recently crash if I put ->Value after them. I guess it's back to the drawing board to try and figure out why.

Thanks again for all the help.

Christian

As I learn the innermost secrets of the around me, they reward me in many ways to keep quiet.

Men with pierced ears are better prepared for marriage. They've experienced pain and bought Jewellery.

Handling Button's Events

MAAK17-Sep-01 1:26

MAAK

17-Sep-01 1:26

I needed to handle dialog button's events like WM_MOUSEMOVE and WM_RBUTTONDOWN, so i created a new class inherited form CButton and handled the events easily but the problem is that i couldn't find a way to access the parent dialog's functions so that i can change the dialog's properties, like for example changing a static text. Is there any way to hadle button's events and enable data exchange with the parent dialog?

Michael P Butler17-Sep-01 2:01

How do I find out what workgroup/domain a host is in?

17-Sep-01 2:01

GetParent will give you a pointer to the parent dialog CWnd class. You can then cast it to your dialog class.

CParentDialog* pParent = (CParentDialog*) GetParent();

Paul Vickery17-Sep-01 0:37

Paul Vickery

17-Sep-01 0:37

I am trying to find some code which will enable me to find out what domain or workgroup a given host is in.

There is a function for this on Win2000, but I need it on NT4.

Does anyone have any ideas?

---
"The way of a fool seems right to him, but a wise man listens to advice" - Proverbs 12:15 (NIV)

Re: How do I find out what workgroup/domain a host is in?

Michael P Butler17-Sep-01 2:07