I am trying to access 3 checkboxes on a page that were created dynamically from database info on PageLoad.
I can see these checkboxes in the web Page Source with ID's equal to T1, T2 and T3. On viewing the page the boxes are checked or unchecked appropriately according to database table values.
I am trying to determine the checked or unchecked states of these checkboxes and then writing it to the database on a button click. All of that is fine.
My problem is the actual "accessing" of those checkboxes/their associated ID's. I have extensively researched and tried everything yet nothing seems to work. I'm sure I'm missing some little nuance.
Here's my code (sorry the indenting is screwed up):
Dim RecCountT As Integer = TNotify.Rows.Count
For i = 0 to RecCountT - 1
Dim strSQLNotifyT as String = "UPDATE dbo._PinCodes SET TextOnOff = #TextOnOff WHERE EmployeeID = #EmployeeID"
Dim myCommand as New SqlCommand(strSQLNotifyT, Conn)
Dim CheckBoxID
CheckBoxID = "T" & i
If CheckBoxID.Checked = True Then
myCommand.Parameters.AddWithValue("#TextOnOff", "on")
ElseIf CheckBoxID.Checked = False Then
myCommand.Parameters.AddWithValue("#TextOnOff", "off")
End If
myCommand.Parameters.AddWithValue("#EmployeeID", TNotify.Rows(i)("EmployeeID").ToString())
Conn.Open()
myCommand.ExecuteNonQuery()
Conn.Close()
Next
Since I do not see the checkbox creation code and assuming the checkBox is created successully and added to the Controls collection, when you create the CheckBox, add:
yourCheckBox.ClientIDMode = ClientIDMode.Static
If this does not work, edit your post with more relevant code to replicate the issue.
Related
I have a database connected to my vb program. One of the forms in the project edits the information in the database. The Form works by searching for a student first, showing the student at the top of the database and then edits the information. the problem is when the information is edited, it edits the first row in the database, not the one chosen (it kind of replaces it). So how do i code it so it can edit only that particular row and not the first one from the database? The Code:
Private Sub cmdEdit_Click()
With frmStudents.Adodc1.Recordset
.Fields(1) = txtFirstName.Text
.Fields(2) = txtLastName.Text
.Fields(3) = txtMarks(0).Text
.Fields(4) = txtMarks(1).Text
.Fields(5) = txtMarks(2).Text
.Update
frmStudents.StudentTable.Refresh '.DataSource = frmStudents.Adodc1
End With
MsgBox "Student Updated Successfully", vbInformation, "Success"
End If
End Sub
I have location DropdownList in my master page. I have set control in my child page which takes properties from master page. Now I am running a query
SELECT * FROM table where city like '"+city.text+"'
here city.text gets value from master page selected cities. But my problem is it's not actually showing records as per city.text has values in it. It shows any random records.
My Code
Master Page
<asp:DropDownList ID="locationSelector" runat="server" AutoPostBack="true">
<asp:ListItem Selected>Pune</asp:ListItem>
<asp:ListItem>Delhi</asp:ListItem>
<asp:ListItem>Chennai</asp:ListItem>
<asp:ListItem>Bangalore</asp:ListItem>
<asp:ListItem>Mumbai</asp:ListItem>
</asp:DropDownList>
Child page VB Code
Dim location As DropDownList = Page.Master.FindControl("locationSelector")
city.Text = location.SelectedItem.ToString
If Not IsPostBack Then
Try
query = "SELECT * FROM hospitals where city like '" + city.Text + "'"
Dim cmd As New MySqlCommand(query, con)
cmd.CommandTimeout = 120
Dim da As New MySqlDataAdapter(cmd)
Dim table As New DataTable
da.Fill(table)
ViewState("Data") = table
hospitals.DataSource = table
hospitals.DataBind()
Catch ex As Exception
Response.Write(ex)
End Try
End If
UPDATE
Protected Sub hospitals_PreRender(ByVal sender As Object, ByVal e As System.EventArgs) Handles Me.PreRender
Dim location As DropDownList = Page.Master.FindControl("locationSelector")
city.Text = location.SelectedItem.ToString
End Sub
Sometimes it also throws TimeOut error. But most of the time It gets results but not as per selected items. What will be any other solution for this?
A couple of tips:
1) Timeout errors can happen for a number of reasons, including lots of other traffic to the site, connection pools all used up etc. I would, for a small list of cities, maybe keep that in a cache after the first call, so that you do not need to load the city list from database every time. Depending on your country, if you only have a few thousand cities, then just put it in an in-memory list.
2) You are using a "SELECT *" which is usually not really cool to other developers, nor to your code if the table contains more than just a city name. IF you write Select CityName from Table, then you will effectively have reduced the amount of data going from your database to your program, and it is clear to the other developers exactly what you're pulling from that table.
3) If you have an ID for the city, it will likely perform even better as string matcing is REALLY slow compared to matching a couple of ID's. I've seen 20% speed improvements by replacing strings with constants, you wouldn't believe how slow strings are in code these days.
4) Last, and I think you may already have done this, make sure that you INDEX every field that you do a WHERE filter on. If you search for Hospitals, then make sure that the Hospitals.City field is indexed to avoid row lookups.
I hope (any) of this helps you :)
As per my understanding you need to change below
to fetch the selected TEXT value use location.SelectedItem.Text instead of location.SelectedItem.ToString()
city.Text = location.SelectedItem.Text // change here
before binding the dropdown control check the no. of rows
if(table.Rows.Count>0)
{
hospitals.DataSource = table;
hospitals.DataBind();
}
I would suggest to use prerender event within page. In prerender event try to access your master page control and get value.
currently I am working on a project named online exam.
All the controls are dynamically created.
I have a webpage where I want to display the student details.
I displayed those details correctly in a table.
Now here comes the time to edit those details.
To edit a record I use the linked button named edit.
When a user clicks on that Linked button the data in that row is replaced with new textboxes.
Upto here I am OK.
Now when I click on the save changes button after making changes to the textboxes.
The old values are not replaced by the new values and the old values remains.
The code for creating textboxes in the table is as follows :
Public Sub Edit_Click(ByVal sender As Object, ByVal e As System.EventArgs)
For x As Integer = 0 To EditList.Count - 1
If sender.id.substring(4) = EditList(x).ID.Substring(4) Then
Session("PreviousRollNo") = RollNoList(x).Text
Dim txtName As New TextBox
txtName.Text = NameList(x).Text
NameList(x).Text = ""
NameList(x).Parent.Controls.Add(txtName)
txtList.Add(txtName)
Dim txtCourse As New TextBox
txtCourse.Text = CourseList(x).Text
CourseList(x).Text = ""
CourseList(x).Parent.Controls.Add(txtCourse)
txtList.Add(txtCourse)
Dim txtAdmissionDate As New TextBox
txtAdmissionDate.Text = AdmissionList(x).Text
AdmissionList(x).Text = ""
AdmissionList(x).Parent.Controls.Add(txtAdmissionDate)
txtList.Add(txtAdmissionDate)
Dim btnSaveChanges As New Button
btnSaveChanges.Text = "Save Changes"
EditList(x).Text = ""
EditList(x).Parent.Controls.Add(btnSaveChanges)
AddHandler btnSaveChanges.Click, AddressOf btnSaveChanges_Click
Session("EditButtonClicked") = True
Dim btnCancel As New Button
btnCancel.Text = "Cancel"
DeleteList(x).Text = ""
DeleteList(x).Parent.Controls.Add(btnCancel)
AddHandler btnCancel.Click, AddressOf btnCancel_Click
Session("CancelButtonClicked") = True
txtName.Focus()
Exit For
End If
Next
End Sub
The code for Save Changes button is as follows :
Public Sub btnSaveChanges_Click(ByVal sender As Object, ByVal e As System.EventArgs)
If txtList(0).Text = "" Then
Dim trError As TableRow = New TableRow
Dim tdError As TableCell = New TableCell
tdError.ColumnSpan = 7
Dim lblError As New Label
lblError.Text = "Please enter name of the student."
lblError.ForeColor = Drawing.Color.Red
tdError.Controls.Add(lblError)
trError.Controls.Add(tdError)
tbl.Controls.Add(trError)
ElseIf txtList(1).Text = "" Then
Dim trError As TableRow = New TableRow
Dim tdError As TableCell = New TableCell
tdError.ColumnSpan = 7
Dim lblError As New Label
lblError.Text = "Please enter the course."
lblError.ForeColor = Drawing.Color.Red
tdError.Controls.Add(lblError)
trError.Controls.Add(tdError)
tbl.Controls.Add(trError)
ElseIf txtList(2).Text = "" Then
Dim trError As TableRow = New TableRow
Dim tdError As TableCell = New TableCell
tdError.ColumnSpan = 7
Dim lblError As New Label
lblError.Text = "Please enter the Admission Date"
lblError.ForeColor = Drawing.Color.Red
tdError.Controls.Add(lblError)
trError.Controls.Add(tdError)
tbl.Controls.Add(trError)
Else
Dim cb As New OleDbCommandBuilder(da)
Dim editRow() As DataRow
editRow = ds.Tables("Student_Detail").Select("Roll_No = '" & Session("PreviousRollNo") & "'")
editRow(0)("Name") = txtList(0).Text
editRow(0)("Course") = txtList(1).Text
editRow(0)("Admission_Date") = txtList(2).Text
da.Update(ds, "Student_Detail")
Page.Response.Redirect("ChangeUserDetails.aspx")
End If
End Sub
I get the error sying that array is out of the bounds. on the first line of the btnSaveChanges_Click.
It means txtlist is always cleared when I click on Save Changes Button.
So I stored txtList in a Session like Session("txtList") = txtList.
and retrieved the data from that. But now I get the old values of the textbox instead of the newer ones.
Here txtList is a list (of Textbox)
Firstly, welcome to the ASP.NET WebForms Page Life Cycle. Remember its pattern with the simple mnemonic: SILVER = Start, Init, Load, Validate, Events, Render.
Secondly, HTTP is stateless. WebForms does an amazing job of hiding this fact from you using ViewState until you do something a little out of the ordinary (as you're now attempting), and it all appears to fall apart. What's really happening is that you're starting to see side-effects of how WebForms is managed, and how it's not as much like WinForms (or another stateful system) as you might think.
When you're responding to an event server-side in WebForms, it's easy to get the impression that nothing has changed. That the entire page is as you left it "last time". All the controls are there, the values you may have set programatically are still set. Magic. Not magic. What's actually happened is the entire page has been re-constructed to respond to that event. How was it re-constructed? By a combination of your page definition (markup), actions taken in control event handlers, and the form data posted back by the client.
Confusing? OK, let's consider an example. Say you've got a page with two controls on it. A textbox named txtInput and a button named btnSubmit with event handler btnSubmit_Click. When the user first requests the page, the HTML for these controls is derived from your markup (aspx page) and returned to the client. Next, the user sets a value in txtInput and clicks the submit button. The server then re-creates the page from scratch based on your markup. At this early stage of the life-cycle, the controls still have their default values. We then hit the Load stage of the life-cycle, and "if the current request is a postback, control properties are loaded with information recovered from view state and control state." In other words, by the time the life-cycle gets to Init, the control has been created from markup, but still has its default value. The Load stage then sets the value according to Postback data.
Left wondering how this applies to your scenario? You're adding your dynamic controls in response to a control event. There's two things wrong with that:
It's too late in the page life-cycle for Init to set the values based on data posted back from the client (recall SILVER, Event is after Init).
Your button click event handler is only run once, in response to the postback where the user clicked the button. But remember on each postback the page is entirely re-created. So the dynamic controls no longer exist as far as the server is concerned! You'll notice that not only are the controls not present server side when responding to the submit event, but after the page has handled it, they're no longer present client-side either.
So what's the answer? Well the "Life-Cycle Events" section of the page I linked offers a clue. It states that the PreInit event be used to (among other things) "Create or re-create dynamic controls". Why would we do it in PreInit? So it's early enough in the page life-cycle for the later events to properly handle it (like setting the values posted back from the client).
Now, I know, you want to add the controls based on the user clicking on the button. How does that fit? The trick is that you've got to manage the "state" yourself. Huh? the state? By this I mean MyDynamicControlsShouldBeShown = true / false. When the button is clicked, creating the controls in response to the button-click event handler is the right action (there's not really any choice there). But you need to store that state somehow so you know on subsequent requests to the page, whether those controls should be re-created in PreInit. One neat option would be to check for the ID of your dynamic control in Request.Form.Keys. If the control ID is present in the Keys collection, then the user is posting back a value for the control, so you should re-create it.
A side-note on the use of Session
Hopefully based on the above you've realised why putting the controls into Session didn't work. But to be clear, the controls you put into the Session object were no longer part of a page that existed (remember, the page gets completely re-created for each request. Those controls were no longer hooked up to the Page events, so didn't get their values populated between Page Init and Load. If somehow it did work, it still wouldn't be a particularly good idea, as Session is not per-request. So what would happen if a user had the same page open in multiple tabs? Strange things, that's what.
I'm using a dynamic pass-through query in Access 2010 to retrieve one or more records from a back-end database. After much trial and error, I plagiarized enough of the right code to retrieve the appropriate records and assign them to unbound text-boxes on my datasheet form during an OnLoad event. The only problem remaining is in displaying multiple records. I've verified that I AM retrieving multiple records, but the contents of each record's fields overwrite the previous values stored to the form's textbox controls, so I always end up with just a single record displayed in my datasheet when I expect to see anywhere from one to 10.
I'm sure it's a simple solution. Can someone please point it out to me?
Private Sub Form_Load()
Dim sqlString As String
sqlString = "SELECT Transmitter_ID, Receiver_ID, UTC_Date, Local_Date from Detections"
If Not IsNull(Me.OpenArgs) Then
sqlString = sqlString & " where " & OpenArgs
End If
Dim cnn As New ADODB.Connection
Dim cmd As New ADODB.Command
Dim rst As ADODB.Recordset
'Define and open connection
cnn.ConnectionString = "DRIVER={SQLite3 ODBC Driver};Database=z:\EWAMP\EWAMP_be_dev.sqlite"
cnn.Open
'Define ADO command
cmd.ActiveConnection = cnn
cmd.CommandText = sqlString
'Populate and enumerate through recordset
Set rst = cmd.Execute
If rst.EOF Then
MsgBox "Nothing found...", vbInformation + vbOKOnly
Exit Sub
Else
Do While Not rst.EOF
'// I'm guessing the problem is with my control assignments, here.
Me.cntl_Receiver_ID.Value = rst("Receiver_ID")
Me.cntl_Transmitter_ID.Value = rst("Transmitter_ID")
Me.cntl_UTC_Date.Value = rst("UTC_Date")
Me.cntl_Local_Date.Value = rst("Local_Date")
Debug.Print {Show me the four control values}
rst.MoveNext
Loop
End If
End Sub
Cheers!
DUHdley
I don't believe a form in Datasheet view can be used as an unbound form. But you can use the ADO recordset as the forms recordset.
Set Me.Recordset = rst
Then just be careful not to close your variable named rst until the form closes.
Another alternative solution is to use an in-memory, fabricated, disconnected ADO recordset. Basically, you'd end up creating a new recordset, append fields to it to match your existing recordset, and then move all the data into your new recordset. But I really don't see the point in doing this if you already have a valid, filled ADO recordset.
If you really need/want to display multiple records in an unbound form, I think you would have to use ActiveX controls such as the GridView, ListView, TreeView, or MSFlexGrid. I've noticed that most skilled, professional Access developers stay away from ActiveX controls as much as possible. If and when they do use them, they usually limit it to only the TreeView and the ListView, I think because they are about the only ActiveX controls that add enough value to be worth putting up with whatever problems they might introduce.
I suggest you take a look at this article concerning the differences between DAO and ADO.
http://www.utteraccess.com/wiki/index.php/Choosing_between_DAO_and_ADO
A reader in another forum pointed me to a solution similar to that posed by HK1, namely Set Me.Recordset = rst. That fixed my original problem, but created another.
First I re-bound my four textbox controls on the unbound form, and then modified the code significantly, using the sample from http://msdn.microsoft.com/en-us/library/ff835419.aspx. The revised code looks like this:
Private Sub Form_Load()
Dim sqlString As String
sqlString = "SELECT Transmitter_ID, Receiver_ID, UTC_Date, Local_Date from Detections"
If Not IsNull(Me.OpenArgs) Then
sqlString = sqlString & " where " & OpenArgs
End If
Dim cn As ADODB.Connection
Dim rs As ADODB.Recordset
'Define and open connection
Set cn = New ADODB.Connection
cn.ConnectionString = "DRIVER={SQLite3 ODBC Driver};Database=z:\EWAMP\EWAMP_be_dev.sqlite;"
cn.Open
'Create an instance of the ADO Recordset class,
'and set its properties
Set rs = New ADODB.Recordset
With rs
Set .ActiveConnection = cn
.Source = sqlString
'// .LockType = adLockOptimistic
.LockType = adLockReadOnly
.CursorType = adOpenKeyset
'// .CursorType = adOpenStatic
.Open
End With
'Set the form's Recordset property to the ADO recordset
Set Me.Recordset = rs
Set cn = Nothing
Set rs = Nothing
End Sub
The form now display four rows for four returned records, 20 rows for twenty records, and on, up to at least 256k rows (as specified by my parameter set). The only remaining teeny tiny problem is that for four or more records, if I press the "last row" navigation button (>|), the local cursor sets focus to one or more of the intermediate rows, and the control's properties sheet refreshes vigorously (multiple times per second). If I have more form rows than can be displayed on the screen, I can not navigate or cursor to the last row. It's as though the record set is constantly being updated.
As you can see, I've played with the RecordSet LockType and CursorType properties (including adOpenDynamic and adOpenForwardOnly, both of which caused a run-time error with the Set Me.Recordset statement). Toggling the LockType between adLockOptimistic and AdLockReadOnly, and the CursorType between adOpenKeyset and adOpenStatic makes no difference in the retrieval performance (which is fantastically fast now!) or the apparent refresh rate (which is even faster, unfortunately).
Perhaps it's worth mentioning that the "Detections" table the sqlString "selects" from contains ~4M records. I was frustrated in my previous attempts to use a form with a data source bound to a passthrough query of this table, because the query always returned the entire 4M records to the client regardless of the filter/WhereClause/OpenArgs parameter I passed to the form. The solution shown above would be perfect if only I could close the connection (I've tried) or otherwise quiesce the RecordSet after I've invoked it once.
I'm trying to allow my users to enter in large lists of data using an ASP.Net GridView control. The affect I'm trying to create is to make the GridView control act like a spreadsheet. The user can freely enter data and tab from column to column and row to row. The user can use a button at the bottom of the page to add rows as needed. There is also a button at the bottom of the form to save as needed.
To do this, I created a DataTable with a bunch of empty rows and bound it to a GridView. The GridView's columns are template columns that contain textboxes. So, when the page opens, it actually looks like a spread sheet. When the user hits the add rows button, I just add another ten rows to the DataTable the GridView is bound to and it works like a charm.
The issue I'm running into is reading the data that the user entered. When the user hits the paging link or the update button, I would like to update the DataTable with the data the user typed in. Here is what I have.
Private Sub UpdateDataTable()
Dim objCatRow As clsCategoriesRow = Session("gvCategoriesRow")
Dim drQuery() As DataRow = Nothing
Dim drRow As DataRow = Nothing
Dim objRow As GridViewRow = Nothing
Dim intRecNo As Integer = 0
Dim txt As TextBox = Nothing
Dim lbl As Label = Nothing
'Loop through all of the rows in the grid view control
For Each objRow In Me.gvCategories.Rows
'Get the label that contains the identity column
lbl = objRow.Cells(GridColumns.Category).FindControl("lblItemRecNo")
intRecNo = lbl.Text
'Update the datarow bound to this grid view row
'First, query the datarow from the data table
drQuery = objCatRow.Table.Select("recno = " & intRecNo)
'Make sure our query returned a row
If Not IsNothing(drQuery) AndAlso drQuery.Count > 0 Then
'Get the value from the textbox in the grid view
txt = objRow.Cells(GridColumns.Category).FindControl("txtItemCategory")
'Upadte the data row with the value the user entered
'THE VALUE IN txt.Text IS EMPTY. HOW CAN I GET THE VALUE THE USER TYPED IN?
drQuery(0)("Category") = txt.Text
'Get the value from the textbox in the grid view
txt = objRow.Cells(GridColumns.SortORder).FindControl("txtItemSortOrder")
'Upadte the data row with the value the user entered
drQuery(0)("sortorder") = txt.Text
End If
Next
End Sub
The issue is that this is not returning what the user typed in. The line
txt = objRow.Cells(GridColumns.Category).FindControl("txtItemCategory")
returns a reference to the textbox in the templated column. But, it contains the previous value, the value from the view state, not the value the user typed in.
How can I get the value the user typed into the grid?
I want to mention that I know how to add EDIT and UPDATE buttons to each row. I would like to avoid doing that way if I can. My users have huge lists of data to enter in and that approach would make the application unusable.
Thanks in advance,
Mike
The form data posted by the user is found in the Page.Request.Form.Item collection. The Page.Request.Form.AllKeys lists the "keys" associated with all of the form item values.
If Page.Request.Form.HasKeys Then
For Each key as String In Page.Request.Form.AllKeys
' step through the keys and use Page.Request.Form.Item(key) to get the data entered
Next
end If
After testing, I was able to get the data from the Request.Form data or the GridView control during page.load on postback, as long as you don't bind the control on postback, but only during the initial request ("GET").
Keep in mind, controls have to be re-created for each request to the page. The Request data posted is used by ASP.NET to repopulate form data controls only after the controls are re-created on the page and the ViewState for the controls is processed, etc.
Request.Form collection
ASP.NET Page Life Cycle
You should replace this:
txt = objRow.Cells(GridColumns.Category).FindControl("txtItemCategory")
with this
txt = objRow.Cells(GridColumns.Category).FindControl("txtItemCategory").Value