MFC - how to locate the cfile opened by cwinapp::opendocumentfile

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When I open an existing file with the stock dialog in an MDI I can see lpszFileName is evaluated in the following function . After that I don't know where to look to set a pointer to the CFile.

C++

Document* CMFCApplication3App::OpenDocumentFile(LPCTSTR lpszFileName)
{
    // TODO: Add your specialized code here and/or call the base class
    
    return CWinApp::OpenDocumentFile(lpszFileName);

}

When I step through the code I never enter CDocument::OnOpenDocument. When I try to retrieve data from the file with CDocument::Serialize it eventually fails with an error box saying "Failed to open document". I don't understand why the process never enters CDocument::OnOpenDocument.

What I have tried:

The serialize trail from CDocument to the class where my data is held in CArray is as follows:

C++

void TaxonTreeDoc::Serialize(CArchive& ar)
{
	Taxa.Serialize(ar);
}

void CTaxon::Serialize(CArchive& archive)
{
	CObject::Serialize(archive);
	if (archive.IsStoring())
		archive << Rank << TName << TParent << IntegumentFileName << ExtCharFileName;
	else
		archive >> Rank >> TName << TParent << IntegumentFileName << ExtCharFileName;
	int i = 1;//test code for break point
}

typedef CArray<ctaxon, ctaxon&> TaxonArray; //dynamic array of taxa

// CArray serialization helper specialized for the CTaxon class

template<> inline void AFXAPI SerializeElements<ctaxon>(CArchive& ar, CTaxon *taxa, INT_PTR nCount)
{

	for (int i = 0; i < nCount; i++, taxa++)
	{
		// Serialize each taxon object
		taxa[i].Serialize(ar);
		//taxa->Serialize(ar);
	}
}

Note I commented out "taxa->Serialize(ar);" and replaced it with and index pointer "taxa[i].Serialize(ar);". However the CFile was, also, failing before this change.

Posted 26-Aug-20 7:15am

Member 14855755

Updated 7-Sep-20 7:45am

Sandeep Mewara

v4

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Comments

Richard MacCutchan 26-Aug-20 13:52pm

Where are you calling OpenDocumentFile from?

Member 14855755 26-Aug-20 16:59pm

It is one of the virtual functions in CMFCApplication3App which is my class derived from CWinApp. I added it in order to trace the path of opening a CDocument from a CDocumentTemplate. That was where I found the file name selected in the standard open file dialog. I assumed somewhere further on in the creation of CDocument, CDocument::OnOpenDocument would be called, but it never happens.

Richard MacCutchan 27-Aug-20 3:35am

I don't understand. If you have created a function, then you must call it from somewhere with a filename as the parameter. I am not actually sure what piece of information you cannot access.

Member 14855755 27-Aug-20 9:33am

These virtual functions are standard parts of MFC MDI. I have simply inherited them into my classes. They are called by the MDI chain of process.

Richard MacCutchan 27-Aug-20 10:27am

But you said above that it is not being called. I suspect there is something missing if that is the case.

Member 14855755 27-Aug-20 15:07pm

I did not create this function, I overrode it. Since it is a virtual function in the base class (CDocument) it should be called without any action on my part. I need advice from someone who knows MFC MDI inner workings. Thanks for trying.

Richard MacCutchan 28-Aug-20 4:25am

See CWinApp Class | Microsoft Docs[^], which explains when that function may get called.

Member 14855755 28-Aug-20 16:45pm

I have no problem with CWinApp:OpenDocumentFile. It is the CDocument::OnOpenDocument function that has me stumped.

Richard MacCutchan 29-Aug-20 2:59am

Yes, but if you read the documentation you will see why, and when, it gets called.

Member 14855755 29-Aug-20 11:36am

Do you perhaps have a link to that part of the documentation? CDocument documentation says nothing about when OnOpenDocument is called.

Richard MacCutchan 29-Aug-20 12:30pm

I gave you the link yesterday. And from there you can find all the MFC documentation.

Member 14855755 29-Aug-20 12:39pm

You keep harping on CWinApp::OpenDocumentFile. That is clearly not the function I seek information on.

Richard MacCutchan 30-Aug-20 7:04am

The first sentence in the documentation page for CDocument::OnOpenDocument:
"Called by the framework as part of the File Open command." The remaining parts explain in more detail what happens, and includes an example.

Member 14855755 29-Aug-20 17:06pm

Arrgh. I just noticed my >> operators are wrong in the serialized read of CTaxon. That is why the data would write, but not read. I still don't understand when CDocument::OnOpenDocument(LPCTSTR) is not called. And another mistake in code that explains why my function is not called. I thought CString would cast to LPCTSTR since it seems to work interchangeably elsewhere in my code.

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Michael Haephrati · Answer 1 · 2020-09-07T07:46:00

Solution 1

You need to call

OpenDocumentFile

and the return value is the handle you are looking for.

C++

CMFCApplication3App *myApp;
Document *myDoc = myApp->OpenDocumentFile(_T("myfilename.txt"));

Then, myDoc should hold the handle to the file.

Posted 7-Sep-20 7:46am

Michael Haephrati