ADO.NET Binding: Handling Errors

/*
User Interfaces in C#: Windows Forms and Custom Controls
by Matthew MacDonald

Publisher: Apress
ISBN: 1590590457
*/

using System;
using System.Drawing;
using System.Collections;
using System.ComponentModel;
using System.Windows.Forms;
using System.Data;

namespace ADO.NET_Binding
{
///

public class HandlingErrors : System.Windows.Forms.Form
{
internal System.Windows.Forms.Label lblErrorSummary;
internal System.Windows.Forms.Button cmdNext;
internal System.Windows.Forms.Button cmdPrev;
internal System.Windows.Forms.Label Label4;
internal System.Windows.Forms.GroupBox GroupBox1;
internal System.Windows.Forms.Label Label3;
internal System.Windows.Forms.Label Label2;
internal System.Windows.Forms.Label Label1;
internal System.Windows.Forms.TextBox txtModelName;
internal System.Windows.Forms.TextBox txtDescription;
internal System.Windows.Forms.TextBox txtUnitCost;
internal System.Windows.Forms.TextBox txtModelNumber;
internal System.Windows.Forms.ComboBox cboModelName;
///

private System.ComponentModel.Container components = null;

public HandlingErrors()
{
//
// Required for Windows Form Designer support
//
InitializeComponent();

//
// TODO: Add any constructor code after InitializeComponent call
//
}

///

protected override void Dispose( bool disposing )
{
if( disposing )
{
if(components != null)
{
components.Dispose();
}
}
base.Dispose( disposing );
}

#region Windows Form Designer generated code
///

private void InitializeComponent()
{
this.lblErrorSummary = new System.Windows.Forms.Label();
this.cmdNext = new System.Windows.Forms.Button();
this.cmdPrev = new System.Windows.Forms.Button();
this.Label4 = new System.Windows.Forms.Label();
this.GroupBox1 = new System.Windows.Forms.GroupBox();
this.Label3 = new System.Windows.Forms.Label();
this.Label2 = new System.Windows.Forms.Label();
this.Label1 = new System.Windows.Forms.Label();
this.txtModelName = new System.Windows.Forms.TextBox();
this.txtDescription = new System.Windows.Forms.TextBox();
this.txtUnitCost = new System.Windows.Forms.TextBox();
this.txtModelNumber = new System.Windows.Forms.TextBox();
this.cboModelName = new System.Windows.Forms.ComboBox();
this.GroupBox1.SuspendLayout();
this.SuspendLayout();
//
// lblErrorSummary
//
this.lblErrorSummary.ForeColor = System.Drawing.Color.Red;
this.lblErrorSummary.Location = new System.Drawing.Point(26, 296);
this.lblErrorSummary.Name = “lblErrorSummary”;
this.lblErrorSummary.Size = new System.Drawing.Size(328, 40);
this.lblErrorSummary.TabIndex = 29;
//
// cmdNext
//
this.cmdNext.Anchor = (System.Windows.Forms.AnchorStyles.Bottom | System.Windows.Forms.AnchorStyles.Right);
this.cmdNext.FlatStyle = System.Windows.Forms.FlatStyle.System;
this.cmdNext.Location = new System.Drawing.Point(322, 348);
this.cmdNext.Name = “cmdNext”;
this.cmdNext.Size = new System.Drawing.Size(92, 28);
this.cmdNext.TabIndex = 28;
this.cmdNext.Text = “Next >>”;
this.cmdNext.Click += new System.EventHandler(this.cmdNext_Click);
//
// cmdPrev
//
this.cmdPrev.Anchor = (System.Windows.Forms.AnchorStyles.Bottom | System.Windows.Forms.AnchorStyles.Left);
this.cmdPrev.FlatStyle = System.Windows.Forms.FlatStyle.System;
this.cmdPrev.Location = new System.Drawing.Point(18, 348);
this.cmdPrev.Name = “cmdPrev”;
this.cmdPrev.Size = new System.Drawing.Size(92, 28);
this.cmdPrev.TabIndex = 27;
this.cmdPrev.Text = “<< Prev"; this.cmdPrev.Click += new System.EventHandler(this.cmdPrev_Click); // // Label4 // this.Label4.Location = new System.Drawing.Point(14, 16); this.Label4.Name = "Label4"; this.Label4.Size = new System.Drawing.Size(88, 16); this.Label4.TabIndex = 26; this.Label4.Text = "Select a Record:"; // // GroupBox1 // this.GroupBox1.Anchor = (((System.Windows.Forms.AnchorStyles.Top | System.Windows.Forms.AnchorStyles.Bottom) | System.Windows.Forms.AnchorStyles.Left) | System.Windows.Forms.AnchorStyles.Right); this.GroupBox1.Controls.AddRange(new System.Windows.Forms.Control[] { this.Label3, this.Label2, this.Label1, this.txtModelName, this.txtDescription, this.txtUnitCost, this.txtModelNumber}); this.GroupBox1.FlatStyle = System.Windows.Forms.FlatStyle.System; this.GroupBox1.Location = new System.Drawing.Point(14, 48); this.GroupBox1.Name = "GroupBox1"; this.GroupBox1.Size = new System.Drawing.Size(400, 228); this.GroupBox1.TabIndex = 25; this.GroupBox1.TabStop = false; // // Label3 // this.Label3.Location = new System.Drawing.Point(220, 56); this.Label3.Name = "Label3"; this.Label3.Size = new System.Drawing.Size(36, 16); this.Label3.TabIndex = 18; this.Label3.Text = "Cost:"; // // Label2 // this.Label2.Location = new System.Drawing.Point(16, 56); this.Label2.Name = "Label2"; this.Label2.Size = new System.Drawing.Size(52, 16); this.Label2.TabIndex = 17; this.Label2.Text = "Model:"; // // Label1 // this.Label1.Location = new System.Drawing.Point(16, 28); this.Label1.Name = "Label1"; this.Label1.Size = new System.Drawing.Size(52, 16); this.Label1.TabIndex = 16; this.Label1.Text = "Name:"; // // txtModelName // this.txtModelName.Location = new System.Drawing.Point(68, 24); this.txtModelName.Name = "txtModelName"; this.txtModelName.Size = new System.Drawing.Size(316, 21); this.txtModelName.TabIndex = 15; this.txtModelName.Text = ""; // // txtDescription // this.txtDescription.Location = new System.Drawing.Point(12, 92); this.txtDescription.Multiline = true; this.txtDescription.Name = "txtDescription"; this.txtDescription.Size = new System.Drawing.Size(372, 116); this.txtDescription.TabIndex = 14; this.txtDescription.Text = ""; // // txtUnitCost // this.txtUnitCost.Location = new System.Drawing.Point(256, 52); this.txtUnitCost.Name = "txtUnitCost"; this.txtUnitCost.Size = new System.Drawing.Size(128, 21); this.txtUnitCost.TabIndex = 13; this.txtUnitCost.Text = ""; // // txtModelNumber // this.txtModelNumber.Location = new System.Drawing.Point(68, 52); this.txtModelNumber.Name = "txtModelNumber"; this.txtModelNumber.Size = new System.Drawing.Size(136, 21); this.txtModelNumber.TabIndex = 12; this.txtModelNumber.Text = ""; // // cboModelName // this.cboModelName.DropDownStyle = System.Windows.Forms.ComboBoxStyle.DropDownList; this.cboModelName.Location = new System.Drawing.Point(106, 10); this.cboModelName.Name = "cboModelName"; this.cboModelName.Size = new System.Drawing.Size(308, 21); this.cboModelName.TabIndex = 24; // // HandlingErrors // this.AutoScaleBaseSize = new System.Drawing.Size(5, 14); this.ClientSize = new System.Drawing.Size(428, 386); this.Controls.AddRange(new System.Windows.Forms.Control[] { this.lblErrorSummary, this.cmdNext, this.cmdPrev, this.Label4, this.GroupBox1, this.cboModelName}); this.Font = new System.Drawing.Font("Tahoma", 8.25F, System.Drawing.FontStyle.Regular, System.Drawing.GraphicsUnit.Point, ((System.Byte)(0))); this.Name = "HandlingErrors"; this.Text = "HandlingErrors"; this.Load += new System.EventHandler(this.HandlingErrors_Load); this.GroupBox1.ResumeLayout(false); this.ResumeLayout(false); } #endregion [STAThread] static void Main() { Application.Run(new HandlingErrors()); } private BindingManagerBase storeBinding; private int currentPage; private bool errFlag; private void HandlingErrors_Load(object sender, System.EventArgs e) { DataSet dsStore = new DataSet(); dsStore.ReadXmlSchema(Application.StartupPath + "store.xsd"); dsStore.ReadXml(Application.StartupPath + "store.xml"); cboModelName.DataSource = dsStore.Tables["Products"]; cboModelName.DisplayMember = "ModelName"; txtModelName.DataBindings.Add("Text", dsStore.Tables["Products"], "ModelName"); txtModelNumber.DataBindings.Add("Text", dsStore.Tables["Products"], "ModelNumber"); txtUnitCost.DataBindings.Add("Text", dsStore.Tables["Products"], "UnitCost"); txtDescription.DataBindings.Add("Text", dsStore.Tables["Products"], "Description"); storeBinding = this.BindingContext[dsStore.Tables["Products"]]; storeBinding.PositionChanged += new EventHandler(Binding_PositionChanged); dsStore.Tables["Products"].ColumnChanged += new DataColumnChangeEventHandler(TableChanging); } private void Binding_PositionChanged(object sender, System.EventArgs e) { if (errFlag) { // Reset the page. storeBinding.Position = currentPage; } else { // Allow the page to change and update the currentPage variable. currentPage = storeBinding.Position; } } private void TableChanging(object sender, System.Data.DataColumnChangeEventArgs e) { string errors = DBStore.ValidateProduct(e.Row); if (errors == "") { errFlag = false; } else { errFlag = true; } lblErrorSummary.Text = errors; } private void cmdNext_Click(object sender, System.EventArgs e) { storeBinding.Position++; } private void cmdPrev_Click(object sender, System.EventArgs e) { storeBinding.Position--; } } public class DBStore { public static string ValidateProduct(DataRow row) { string errors = ""; if (((decimal)row["UnitCost"]) <= 0) { errors += "* UnitCost value too low "; } if (row["ModelNumber"].ToString() == "") { errors += "* You must specify a ModelNumber "; } if (row["ModelName"].ToString() == "") { errors += "* You must specify a ModelName "; } return errors; } } } ADO.NETBinding.zip( 76 k)[/csharp]