Tricks of the Windows Gam…ming Gurus (2nd Edition)/Disc2.iso/msdn_vcb/samples/vc98/mfc/database/daoenrol/crsform.cpp

C/C++ Source or Header | 1998-03-27 | 4.9 KB | 178 lines

// crsform.cpp : implementation file
//
// This is a part of the Microsoft Foundation Classes C++ library.
// Copyright (C) 1992-1998 Microsoft Corporation
// All rights reserved.
//
// This source code is only intended as a supplement to the
// Microsoft Foundation Classes Reference and related
// electronic documentation provided with the library.
// See these sources for detailed information regarding the
// Microsoft Foundation Classes product.

#include "stdafx.h"
#include "DaoEnrol.h"

#include "coursese.h"
#include "addform.h"
#include "crsform.h"
#include "sectset.h"
#include "denrldoc.h"
#include "mainfrm.h"
#include "resource.h"

#ifdef _DEBUG
#define new DEBUG_NEW
#undef THIS_FILE
static char THIS_FILE[] = __FILE__;
#endif

/////////////////////////////////////////////////////////////////////////////
// CCourseForm

IMPLEMENT_DYNCREATE(CCourseForm, CAddForm)

BEGIN_MESSAGE_MAP(CCourseForm, CAddForm)
    //{{AFX_MSG_MAP(CCourseForm)
    ON_COMMAND(ID_RECORD_ADD, OnRecordAdd)
    ON_COMMAND(ID_RECORD_DELETE, OnRecordDelete)
    ON_COMMAND(ID_RECORD_REFRESH, OnRecordRefresh)
    //}}AFX_MSG_MAP
END_MESSAGE_MAP()

CCourseForm::CCourseForm()
    : CAddForm(CCourseForm::IDD)
{
    //{{AFX_DATA_INIT(CCourseForm)
    m_pSet = NULL;
    //}}AFX_DATA_INIT
}

CCourseForm::~CCourseForm()
{
}

void CCourseForm::DoDataExchange(CDataExchange* pDX)
{
    CDaoRecordView::DoDataExchange(pDX);
    //{{AFX_DATA_MAP(CCourseForm)
    DDX_Control(pDX, IDC_COURSEID, m_ctlCourseID);
    DDX_FieldText(pDX, IDC_COURSEID, m_pSet->m_CourseID, m_pSet);
    DDX_FieldText(pDX, IDC_HOURS, m_pSet->m_Hours, m_pSet);
    DDX_FieldText(pDX, IDC_TITLE, m_pSet->m_CourseTitle, m_pSet);
    //}}AFX_DATA_MAP
}

BOOL CCourseForm::OnMove(UINT nIDMoveCommand)
{
    BOOL bWasAddMode = FALSE;
    CString strCourseID;
    if (m_bAddMode == TRUE)
    {
        m_ctlCourseID.GetWindowText(strCourseID);
        bWasAddMode = TRUE;
    }
    if (CAddForm::OnMove(nIDMoveCommand))
    {
        m_ctlCourseID.SetReadOnly(TRUE);
        if (bWasAddMode == TRUE)
        {
            CUpdateHint hint;
            hint.m_strCourse = strCourseID;
            GetDocument()->UpdateAllViews(this, HINT_ADD_COURSE, &hint);
        }
        return TRUE;
    }
    return FALSE;
}

/////////////////////////////////////////////////////////////////////////////
// CCourseForm message handlers

CDaoRecordset* CCourseForm::OnGetRecordset()
{
    return m_pSet;
}

void CCourseForm::OnInitialUpdate()
{
    CDaoEnrolDoc* pDoc = (CDaoEnrolDoc*)GetDocument();
    CDaoDatabase* pDatabase = pDoc->GetDatabase();
    if (!pDatabase->IsOpen())
        return;
    m_pSet = &pDoc->m_courseSetForForm;
    m_pSet->m_strSort = "CourseID";
    m_pSet->m_pDatabase = pDatabase;
    CDaoRecordView::OnInitialUpdate();
}


void CCourseForm::OnRecordAdd()
{
    CAddForm::RecordAdd();
    m_ctlCourseID.SetReadOnly(FALSE);
}


void CCourseForm::OnRecordDelete()
{
    // The STDREG.MDB Student Registration database in Access Format
    // does not require a programmatic validation to
    // assure that a course is not deleted if any sections exist.
    // That is because the STDREG.MDB database has been pre-built with
    // such an referential integrity rule.  If the user tries to
    // delete a course that has a section, a CDBException will be
    // thrown, and ENROLL will display the SQL error message
    // informing the user that the course cannot be deleted.
    //
    // A Student Registration database initialized by the STDREG
    // tool will not have any such built-in referential integrity
    // rules.  For such databases, the following code assumes the
    // burden of assuring that the course is not deleted if a section
    // exists.  The reason that STDREG does not add referential
    // integrity checks to the Student Registration database is that
    // some databases such as SQL Server do not offer SQL, via ODBC,
    // for creating referential integrity rules such as "FOREIGN KEY".
    //
    // The deletion of a course is not the only place ENROLL
    // needs a programmatic referential integrity check.  Another example
    // is a check that a duplicate course or seciton is not added.
    // For simplicity, ENROLL does not make these other checks.


    CDaoEnrolDoc* pDoc = (CDaoEnrolDoc*)GetDocument();
    CsectionSet sectionSet;
    sectionSet.m_pDatabase = pDoc->GetDatabase();
    sectionSet.m_strFilter = "CourseID = CourseIDParam";
    sectionSet.m_strCourseIDParam = m_pSet->m_CourseID;
    try
    {
        sectionSet.Open();
    }
    catch (CDaoException* e)
    {
        AfxMessageBox(e->m_pErrorInfo->m_strDescription);
        e->Delete();
    }
    if (!sectionSet.IsEOF())
    {
        AfxMessageBox(IDS_CANNOT_DELETE_COURSE_WITH_SECTION);
        return;
    }

    CUpdateHint hint;
    hint.m_strCourse = m_pSet->m_CourseID;
    if (CAddForm::RecordDelete())
        GetDocument()->UpdateAllViews(this, HINT_DELETE_COURSE, &hint);
}

void CCourseForm::OnRecordRefresh()
{
    if (m_bAddMode == TRUE)
    {
        m_pSet->CancelUpdate();
        m_ctlCourseID.SetReadOnly(TRUE);
    }
    CAddForm::RecordRefresh();
}