/**************************************************************************
* @author : Chandar
* @version 1.0
* Development
Environment : Microsoft Visual Studio .Net
* Name of the
File : ProductDetails.cs
* Creation/Modification
History :
12-Oct-2002 Created
* Overview:
* This class
defines the methods to retrieve and update details of a
* particular
product to database. It also shows how Safe Type Mapping feature
* of ODP.NET can
be used to prevent precision loss while retrieving high
* precision data
from database.
*****************************************************************************/
using System;
using System.Drawing;
using System.Collections;
using System.ComponentModel;
using System.Windows.Forms;
using System.Data;
using Oracle.DataAccess.Client;
namespace SafeTypeMapping
{
/// <summary>
///
Definition of ProductDetails class.
/// </summary>
public class
ProductDetails : System.Windows.Forms.Form
{
// variable to communicate with
database
OracleDataAdapter productsAdapter;
// variable to get data from
the database
DataSet detailsDataSet;
// variable to store product ID
of the product whose details are sought
int productID;
// variable to store the user
selection in Products screen
bool safeType;
//definition of various
controls on the form
private
System.Windows.Forms.Button cmdUpdate;
private
System.Windows.Forms.Button cmdClose;
private
System.Windows.Forms.Label lblPrice;
private
System.Windows.Forms.TextBox txtPrice;
private
System.Windows.Forms.Label lblProduct;
private
System.Windows.Forms.Label lblName;
private
System.Windows.Forms.TextBox txtWeight;
private
System.Windows.Forms.Label lblWeight;
private System.Windows.Forms.Label
lblPID;
private
System.Windows.Forms.Label lblID;
/// <summary>
/// Required designer variable.
/// </summary>
private
System.ComponentModel.Container components = null;
public ProductDetails()
{
InitializeComponent();
}
/**********************************************************************
* This method retrieves the details of products from database in
* a DataSet variable using OracleDataAdapter. It uses Safe Type
* Mapping for "Weight" and "Price" column to
avoid precision loss while
* retrieving it from database. When Safe Type Mapping is used the
* column data is retrieved as String type rather than default
* .NET types.
* If Safe Type Mapping is not used, the method throws an
* "Arithmetic operation resulted in an overflow" exception
* when precision of column data is higher than that can be handled
* by defalut .NET types.
**********************************************************************/
public bool getProductDetails(int
productID, bool safeType)
{
this.productID
=productID;
this.safeType=safeType;
try
{
//Instantiate
OracleDataAdapter to communicate with database
productsAdapter = new
OracleDataAdapter();
// variable to
automatically generate commands for making changes
// through DataSet
OracleCommandBuilder productsCmdBuilder = new OracleCommandBuilder(productsAdapter);
//Set the select
command to fetch product details
productsAdapter.SelectCommand = new OracleCommand("SELECT " +
"Product_ID,Product_Name,Weight ,
Price FROM "+
" products WHERE
product_id="+productID,
ConnectionManager.conn);
//AddWithKey sets
the Primary Key information to complete the
//schema
information
productsAdapter.MissingSchemaAction =
MissingSchemaAction.AddWithKey;
if(safeType)
{
//Add Safe
Mapping for Weight column so that it is retrieved
//as String
type instead of default .NET type to avoid precision loss
productsAdapter.SafeMapping.Add("WEIGHT",typeof(string));
//Add Safe
Mapping for Price column so that it is
retrieved
//as String
type instead of default .NET type to avoid prcision loss
productsAdapter.SafeMapping.Add("PRICE",typeof(string));
}
//Instantiate
DataSet object
detailsDataSet = new
DataSet("DetailsDataSet");
//Fill the DataSet
with data from 'Products' database table
productsAdapter.Fill(detailsDataSet,
"Products");
// Get the row
containing details of product
DataRow row
=detailsDataSet.Tables["Products"].Rows[0];
// display the
product details on form controls
lblID.Text
=row["Product_ID"].ToString();
lblName.Text = row["Product_Name"].ToString();
txtWeight.Text =
row["Weight"].ToString();
txtPrice.Text =
row["Price"].ToString();
}
catch(Exception ex)
{
//Display error
message
MessageBox.Show(ex.Message);
return false;
}
return true;
}
/*****************************************************************
* This method updates the details of products into the
database.
* The DataSet object is
first edited to incorporate the changes
* to product details and then this DataSet is used to update the
* database table. Safe Type Mapping is used for "Weight"
and
* "Price" column to avoid precision loss while updating
the values
* into database.
*****************************************************************/
private void updateProductDetails()
{
try
{
//get the Row to be
updated
DataRow detailsRow
=detailsDataSet.Tables[0].Rows.Find(productID);
// check if user
has made any changes to data values
if(txtWeight.Text.Equals(detailsRow["Weight"].ToString())
&&
txtPrice.Text.Equals(detailsRow["Price"].ToString()))
{
MessageBox.Show("No changes
made");
return;
}
//Start the edit
operation on the current row
detailsRow.BeginEdit();
//Assigning the
value of product weight
detailsRow["Weight"] =
txtWeight.Text;
//Assigning the
value of product price
detailsRow["Price"] =
txtPrice.Text;
//End the editing
current row operation
detailsRow.EndEdit();
// update the
changes in DataSet to database
productsAdapter.Update(detailsDataSet,"Products");
// message on
successful updation.
MessageBox.Show("Update
Successful");
}
catch(Exception e)
{
//Display error
message
System.Windows.Forms.MessageBox.Show(e.Message);
}
}
/*************************************************************
* This event is fired when "Update" button is clicked
* It calls method to update changes to database.
* ***********************************************************/
private void cmdUpdate_Click(object
sender, System.EventArgs e)
{
// check if input data is
valid
bool proceed
=validateInput();
if(proceed)
{
// update details
to database
updateProductDetails();
// get the udpated
details
getProductDetails(productID,safeType);
}
}
/***************************************************************
* This method validates the user input before updating it to
* database
**************************************************************/
private bool validateInput()
{
//if weight of product is
not entered
if(txtWeight.Text=="")
{
MessageBox.Show("Enter Product
Weight");
return false;
}
// check if product
weight is valid number
else if(txtWeight.Text!="")
{
try
{
//Parse the
string to unsigned integer
double
temp =System.Double.Parse(txtWeight.Text);
if(temp<=0)
{
MessageBox.Show("Weight
cannot be zero or negative");
return
false;
}
}
catch(Exception
ne)
{
txtWeight.Text="";
MessageBox.Show("Enter valid
Product Weight");
return false;
}
}
//if price of product is
not entered
if(txtPrice.Text=="")
{
MessageBox.Show("Enter Product
Price");
return false;
}
// check if product
price is valid number
else if(txtPrice.Text!="")
{
try
{
//Parse the
string to unsigned integer
double
temp =System.Double.Parse(txtPrice.Text);
if(temp<=0)
{
MessageBox.Show("Price
cannot be zero or negative");
return
false;
}
}
catch(Exception
ne)
{
txtPrice.Text="";
MessageBox.Show("Enter valid
Product Price");
return false;
}
}
return true;
}
/*************************************************************
* This event is fired when "Close" button is clicked
* It closes the current form.
* ***********************************************************/
private void cmdClose_Click(object
sender, System.EventArgs e)
{
this.Close();
}
#region Windows Form Designer
generated code
/// <summary>
/// Required method for Designer support - do not modify
/// the contents of this method with the code editor.
/// </summary>
private void InitializeComponent()
{
this.lblProduct = new System.Windows.Forms.Label();
this.lblWeight = new System.Windows.Forms.Label();
this.lblPrice = new System.Windows.Forms.Label();
this.txtPrice = new System.Windows.Forms.TextBox();
this.cmdUpdate = new System.Windows.Forms.Button();
this.cmdClose = new System.Windows.Forms.Button();
this.lblName = new System.Windows.Forms.Label();
this.txtWeight = new System.Windows.Forms.TextBox();
this.lblPID = new System.Windows.Forms.Label();
this.lblID = new System.Windows.Forms.Label();
this.SuspendLayout();
//
// lblProduct
//
this.lblProduct.Font
= new System.Drawing.Font("Tahoma",
9.75F, System.Drawing.FontStyle.Bold, System.Drawing.GraphicsUnit.Point,
((System.Byte)(0)));
this.lblProduct.Location
= new System.Drawing.Point(32, 56);
this.lblProduct.Name
= "lblProduct";
this.lblProduct.Size
= new System.Drawing.Size(104, 24);
this.lblProduct.TabIndex
= 0;
this.lblProduct.Text
= "Product Name";
//
// lblWeight
//
this.lblWeight.Font
= new System.Drawing.Font("Tahoma",
9.75F, System.Drawing.FontStyle.Bold, System.Drawing.GraphicsUnit.Point,
((System.Byte)(0)));
this.lblWeight.Location
= new System.Drawing.Point(32, 112);
this.lblWeight.Name
= "lblWeight";
this.lblWeight.Size
= new System.Drawing.Size(80, 32);
this.lblWeight.TabIndex
= 2;
this.lblWeight.Text
= "Weight (g)";
//
// lblPrice
//
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