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ASP.Net Form Controls. ASP.Net Form Controls Textbox, Button, Label, Literal Triggering input processing RadioButtonList DropDownList CheckBoxList Form Control Validations. ASP.Net Server-side Processing. HTTP Request. HTTP Response. Client. Microsoft Web Server. Web Page. VB.
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ASP.Net Form Controls • ASP.Net Form Controls • Textbox, Button, Label, Literal • Triggering input processing • RadioButtonList • DropDownList • CheckBoxList • Form Control Validations
ASP.Net Server-side Processing HTTP Request HTTP Response Client Microsoft Web Server Web Page VB IIS JScript Scripting Engines Data Components Database Source: Active Server Pages, Wille & Koller, Sams Publishing
ASP.Net Server-side Processing Request for Default.aspx Microsoft Web Server Client Default.aspx sent as a form Clicking Submit button sends Default.aspx page Server runs Button_Click subroutine, writes any output described by subroutine, sends Default.aspx back
ASP.Net Form Controls • Textbox (to get user text input) • Button (to trigger form processing – also can be done by Autopostback when available) • Label or Literal (to display output) • RadioButtonList • DropDownList • CheckBoxList
VB Language Essentials • Declaring variables Dimvariable as Type Dim d1 as Date Dim x, y as Integer Dim z as Single Dim w as Double Dim myname as String Dim misc as Object (a catchall type, to be avoided)
VB Language Essentials • Operators • Mathematical: +, -, *, /, % • Assignment: = • Logical: >, <, >=, <=, <>, AND, OR, NOT • E.g., If x<100 AND x<>90 Then x = x+10 Else x = x+5 End If (If x less than 100 AND x not equal to 90 Then)
VB Language Essentials • If…Else…End If If condition Then statements if condition is true Else statements if condition is false End If • If…Elseif…Else…End If If condition1 Then statements if condition1 is true Elseif condition2 Then statements if condition2 is true Else statements if condition1 & condition2 are false End If
VB Language Essentials • For loops For x = initial value To final value Step value statements within the for loop Next n=20 For x = 1 To n Step 2 Response.Write “Value of X is “ & x total = total + x Next
VB Language Essentials • Sub-routines Sub printtimes(n as Integer) Dim x as Integer For x = 1 To n Response.Write “Printing ” & x & “time” Next End Sub • Calling subroutines <% Dim n1 as Integer n1=10 printtimes(n1) %>
VB Language Essentials • Do While loop Do While condition statements within while loop Loop Dim x,n, total as Integer x=1 n=20 total = 0 Do While x<=n Response.Write “X is ” & x x = x+1 total = total + x Loop
RadioButtonList • Properties • ID, Itemlist (text, value) • Accessing RadioButtonList in VB subroutine • Assume RadioButtonList ID = Rblist1 • Rblist1.SelectedIndex (returns index of selected item, -1 if no item selected) • Rblist1.SelectedValue or Rblist1.SelectedItem.Value (returns value attribute of selected item) • Rblist1.SelectedItem.Text (returns text attribute of selected item) • Autopostback (refreshes the aspx page when selection is changed)
DropDownlist • Properties • ID, Itemlist (text, value) • Accessing DropDownList in VB subroutine • Assume DropDownList ID = Dlist1 • Dlist1.SelectedIndex (returns index of selected item) • Dlist1.SelectedValue or Dlist1.SelectedItem.Value (returns value attribute of selected item) • Dlist1.SelectedItem.Text (returns text attribute of selected item) • Autopostback • Default Selected Item
CheckBoxList • Properties • ID, Itemlist (text, value) • Accessing CheckBoxList in VB subroutine • Assume CheckBoxList ID = Cblist1 • Cbist1.SelectedIndex (returns index of first selected item in the list of checkboxes) • Cblist1.Items.Count (returns number of items created in the list and NOT the number of checkboxes checked) • Cblist1.Items(i) – each item is accessed by its index i • Cblist1.Items(i).Selected (returns True if Item(i) is checked, where i is an index variable created outside the CheckBoxList control) • Cblist1.Items(i).Text (returns the text attribute of Item(i)) • Cblist1.Items(i).Value (returns the value attribute of Item(i))
Processing Checkboxes - Example • Inside the Button_Click Subroutine (Assume the ID for the Checkboxlist = CbList1) Dim i, count, total As Integer, s As String count = 0 total = 0 s = "" ‘For loop is to count and total only the checkboxes that are checked For i = 0 To (CbList1.Items.Count - 1) If CbList1.Items(i).Selected Then count = count + 1 total = total + CbList1.Items(i).Value s = s & CbList1.Items(i).Text & ";" End If Next Label1.Text = "The selected options are: " & s Label2.Text = "Number of options checked: " & count Label3.Text = "Total value of selected options: " & total
Form Controls Validators(Client-side) • Required Field (Textbox, Radiobuttonlist) • Control to validate (required for all validators) • Error Message • Display • Regular Expression (Textbox) • Type of expression to compare with • Range • Maximum Value • Minimum Value • Data type • Compare • Compare with a static value or another control