cardetail.aspx

ASP.NET Web Forms Techniques

    btnCancel.Enabled = true;

    // show Save button
    btnSave.Visible = true;
  }
  else {

    // display the error details in the page
    lblTerms.Text = " ";
    lblFinanceResult.Text = "<b>" + sError + "</b>";
    lblFinanceInfo.Text = "";

    // hide Save button
    btnSave.Visible = false;
  }
}

// -------------------------------------------------------------------

// function to calculate payment terms from current user selections
String CalculateFinanceTerms() {

  Decimal fInterestRate;
  Decimal fBasePrice, fTotalInterest, fMonthlyPayment;
  Decimal fTotalPrice, fPaymentPer1000;
  int iMonths;

  // get interest rate from web.config file
  try {
    fInterestRate = Decimal.Parse(ConfigurationSettings.AppSettings["XroxCarsInterestRate"]);
  }
  catch (Exception e) {
    return "Interest Rate Error in web.config file";
  }

  // get basic price including extras from prices array
  try {
    fBasePrice = Decimal.Parse(aCurrentPrice[0]);
  }
  catch (Exception e) {
    return "Basic Price Error in Session Array";
  }

  // see which payment option is selected
  if (optByAmount.Checked) {   // paying a specified amount each month

    try {

      // get monthly payment from text box as a Decimal number
      fMonthlyPayment = Decimal.Parse(txtMonthPayment.Text);

    }
    catch (Exception e) {
      return "The value for the monthly payment is not a valid number.";
    }

    // calculate the number of payments required and other values
    // parameter fMonthlyPayment is ByRef and will be updated within
    // the function to show actual payment required
    iMonths = GetNumberPayments(fBasePrice, ref fMonthlyPayment);

    // see if the resulting term is acceptable
    if ((iMonths == 0) || (iMonths > 120)) {
      return "The monthly payment specified is not sufficient to repay the loan.";
    }
  }
  else {  // paying over a specified number of months

    try {

      // get values from drop-down list
      iMonths = Int32.Parse(lstFinanceMonths.SelectedItem.Text);
      fPaymentPer1000 = Decimal.Parse(lstFinanceMonths.SelectedItem.Value);

      // calculate payment for this vehicle price
      fMonthlyPayment = fPaymentPer1000 * fBasePrice / 1000;

    }
    catch (Exception e) {
      return "The value for the number of months is not a valid number.";
    }
  }

  // calculate total price
  fTotalPrice = fMonthlyPayment * iMonths;
  fTotalInterest = fTotalPrice - fBasePrice;

  // fill in the finance terms section of the array of values
  aCurrentPrice[1] = fInterestRate.ToString();
  aCurrentPrice[2] = fTotalInterest.ToString("#,##0.00");
  aCurrentPrice[3] = fTotalPrice.ToString("#,##0.00");
  aCurrentPrice[4] = iMonths.ToString();
  aCurrentPrice[5] = fMonthlyPayment.ToString("#,##0.00");

  // update Session with new array values
  Session[sPricesSessionKey] = aCurrentPrice;

  return "";   // empty string indicates all worked OK

}

// -------------------------------------------------------------------

// get number of payments required given desired monthly payment
// by searching through PMT values in DataSet table (alternatively
// could do it by iterating the contents of the DropDownList)
// Note that fMonthlyPayment parameter is ByRef and the value will
// be updated within function to actual payment required
int GetNumberPayments(Decimal fBasePrice,ref Decimal fMonthlyPayment) {

  Decimal fPaymentPer1000;

  // calculate the maximum payment per 1000 acceptable to client
  fPaymentPer1000 = fMonthlyPayment * 1000 / fBasePrice;

  // create suitable filter and sort criteria to get array of rows
  // where first contains highest acceptable payment per 1000
  String sFilter = "Payment <= " + fPaymentPer1000;
  String sSort = "Payment DESC";

  try {

    // get reference to table in DataSet and select matching rows
    DataTable oDTFinance = oCarsDS.Tables["FinancePMTRates"];
    DataRow[] aRows =  oDTFinance.Select(sFilter, sSort);

    // calculate payment for this vehicle price using actual
    // payment required from second column of data row
    fMonthlyPayment = (Decimal)aRows[0]["Payment"] * fBasePrice / 1000;

    // extract number of months from first column of row
    return (int)aRows[0]["Months"];
  }
  catch (Exception e) {

    // return zero if cannot calculate the result
    // will occur if payment is too low (no data rows selected)
    return 0;
  }
}

// -------------------------------------------------------------------

// routine to clear any current finance terms for "Cancel" button
void ClearFinanceTerms(object oSender, EventArgs oArgs) {

  // clear the finance terms section of the array of values
  aCurrentPrice[1] = "";
  aCurrentPrice[2] = "";
  aCurrentPrice[3] = "";
  aCurrentPrice[4] = "";
  aCurrentPrice[5] = "";

  // update Session with new array values
  Session[sPricesSessionKey] = aCurrentPrice;

  // clear any current finance terms text from page
  lblTerms.Text = "&nbsp;";
  lblFinanceResult.Text = "Select the payment options you prefer and click <b>Calculate</b>.";
  lblFinanceInfo.Text = "";

  // disable the "Cancel" button
  btnCancel.Enabled = false;
}

// -------------------------------------------------------------------

// routine to update price as optional extras are selected
void SelectExtras(object oSender, EventArgs oArgs) {
  CalculateCarPrice();
}

// -------------------------------------------------------------------

// routine to select the color chosen by the user and update car image
void SelectColor(object oSender, ImageClickEventArgs oArgs) {
  HtmlInputImage oCtrl = (HtmlInputImage)oSender;
  tclColor.BgColor = oCtrl.Alt;
  CalculateCarPrice();
}

// -------------------------------------------------------------------

// routine to show range of colors when a Standard/Metallic is selected
void SelectColorType(object oSender, EventArgs oArgs) {

  // get reference to table in the DataSet
  DataTable oDTColor = oCarsDS.Tables["CarColors"];

  // fill the DataList of colors depending on setting of
  // the Standard/Metallic radio buttons
  DataView oDTView = oDTColor.DefaultView;
  oDTView.RowFilter = "IsMetallic = " + optColorType.SelectedIndex;
  dlsColors.DataSource = oDTView;
  dlsColors.DataBind();
  oDTView.RowFilter = "";
}

// -------------------------------------------------------------------

// routine to select row in DataGrid when an engine is selected
void SelectEngine(object oSender, EventArgs oArgs) {
  dgrEngine.SelectedIndex = optEngine.SelectedIndex;
  CalculateCarPrice();
}

// -------------------------------------------------------------------

// routine to interact with tree view controls on "Details" page so
// that only one node is open at a time. Only affects non-IE 5.5
// browsers, which handle updates to the display server-side
// routine runs whenever a node is expanded to show its contents
void NodeExpanded(object oSender, TreeViewClickEventArgs oArgs) {

  // iterate through all the top-level child nodes of the control
  TreeView oCtrl = (TreeView)oSender;
  foreach (TreeNode oTopNode in oCtrl.Nodes) {

    // if it is not the node that was just expanded, collapse it
    if (oTopNode != oCtrl.GetNodeFromIndex(oArgs.Node)) {
      oTopNode.Expanded = false;
    }
  }
}

// -------------------------------------------------------------------

// function to get selected car details as a DataSet
// DataSet is cached in user's Session after first access
DataSet GetCarDetailsDS(String sCarID) {

  // to hold DataSet for the results
  DataSet dsCarDetail = null;

  // to hold Session key for DataSet
  String sSessionKey = "XroxCar" + sCarID + "Details";

  // try and get DataSet from user's Session
  dsCarDetail = (DataSet)Session[sSessionKey];

  if (dsCarDetail == null) {   // not in Session - get from database

    // to hold stored procedure names
    String sCarProcName = "GetAllCarDetails";
    String sColorProcName = "GetAllCarColors";
    String sExtrasProcName = "GetAllCarExtras";
    String sFinancePMTProcName = "GetFinancePMTRates";

    String sConnect = ConfigurationSettings.AppSettings["XroxCarsConnectString"];
    SqlConnection sqlConn = new SqlConnection(sConnect);
    SqlCommand sqlComm = new SqlCommand(sCarProcName, sqlConn);
    sqlComm.CommandType = CommandType.StoredProcedure;

    try {

      // create a new empty DataSet for the results
      dsCarDetail = new DataSet();

      // and fill it from the database
      sqlComm.Parameters.Add("@CarID", sCarID);
      SqlDataAdapter daCarDetail = new SqlDataAdapter(sqlComm);
      sqlConn.Open();
      daCarDetail.Fill(dsCarDetail, "CarDetails");
      sqlComm.CommandText = sColorProcName;
      daCarDetail.Fill(dsCarDetail, "CarColors");
      sqlComm.CommandText = sExtrasProcName;
      daCarDetail.Fill(dsCarDetail, "CarExtras");
      sqlComm.CommandText = sFinancePMTProcName;
      sqlComm.Parameters.Clear();
      daCarDetail.Fill(dsCarDetail, "FinancePMTRates");

      // save DataSet in Session for next postback
      Session[sSessionKey] = dsCarDetail;

    }
    catch (Exception e) {
      return null;
    }
    finally {
      sqlConn.Close();
    }
  }
  return dsCarDetail;
}

// -------------------------------------------------------------------

// routine to save current configuration of vehicle in database
void SaveCarDetails(object oSender, ImageClickEventArgs oArgs ) {

  // collect the values we'll need for the tblQuoteOrder table
  String sAnonUserID = (String)Session["WccUserID"];
  int iCarID = Int32.Parse(sCarID);
  String sCarName = (String)oCarsDS.Tables["CarDetails"].Rows[0]["Model"];
  Decimal dBasePrice = Decimal.Parse(aCurrentPrice[0]);
  Decimal dTotalPrice = dBasePrice;
  Decimal dInterest = 0;
  Decimal dPaymentAmount = 0;
  int iPaymentMonths = 0;

  if (aCurrentPrice[2] != "") {
    dInterest = Decimal.Parse(aCurrentPrice[2]);
    dTotalPrice = Decimal.Parse(aCurrentPrice[3]);
    iPaymentMonths = Int32.Parse(aCurrentPrice[4]);
    dPaymentAmount = Decimal.Parse(aCurrentPrice[5]);
  }
  int iEngineID = int.Parse(optEngine.SelectedItem.Value);
  String sEngineName = optEngine.SelectedItem.Text;

  // extract color from DataSet as in CalculateCarPrice routine
  String sColorName = tclColor.BgColor;
  String sFilter = "Color = '" + sColorName + "'";
  DataRow[] aRows = oCarsDS.Tables["CarColors"].Select(sFilter, "");
  int iColorID = (int)aRows[0]["ColorID"];

  // specify the stored procedure names
  String sSaveQuote = "InsertNewQuote";
  String sSaveExtraLine = "InsertNewQuoteExtraLine";

  // create connection and command objects
  String sConnect = ConfigurationSettings.AppSettings["XroxCarsConnectString"];
  SqlConnection sqlConn = new SqlConnection(sConnect);
  SqlCommand sqlComm = new SqlCommand(sSaveQuote, sqlConn);
  sqlComm.CommandType = CommandType.StoredProcedure;

  // declare a variable to hold a Transaction object
  SqlTransaction oTransaction = null;

  try {

    // open connection and start a transaction
    sqlConn.Open();
    oTransaction = sqlConn.BeginTransaction();

    // attach transaction to Command object
    sqlComm.Transaction = oTransaction;

    // add parameters to Command
    sqlComm.Parameters.Add("@UserID", sAnonUserID);
    sqlComm.Parameters.Add("@CarID", iCarID);
    sqlComm.Parameters.Add("@CarName", sCarName);
    sqlComm.Parameters.Add("@EngineID", iEngineID);
    sqlComm.Parameters.Add("@EngineName", sEngineName);
    sqlComm.Parameters.Add("@ColorID", iColorID);