Dim Application = From AL In db.AnnualLeave _
Where AL.Approval <> True _
Select LeaveID, EmpID, Name
GridView3.DataSource = Application
GridView3.DataBind()
after calling `GridView3.DataBind(), why do i still get
Index was out of range. Must be non-negative and less than the size of the collection. Parameter name: index.
at this line of code GridView3.Columns(1).Visible = False yet the grid has rows and more than 2 columns. i found a thread about similar problem here http://forums.asp.net/t/1025678.aspx/1
Note that the Gridview columns have NOT been defined at design time.
`
You need to be careful where you place your code in asp.net. If you placed that GridView3.Columns(1).Visible = False
code in the wrong place at the wrong time then yes, it would throw an error.
I suggest reading up on ASP.NET Page Lifecyle
Related
I have a listbox in VB.NET that allows users to select multiple categories. I need to put these categories into a database and need the index value from the listbox of the categories as the database works off IDs. SelectedItems (with an s) does not work in the net application.
I have tried the following code:
For Each category As ListItem In CategoryListBox.Items
If category.Selected Then
Dim courseCategory As New CourseCategory
courseCategory.CourseID = course.ID
courseCategory.CategoryID = CategoryListBox.SelectedIndex
Using courseCategoryEntities As New Eng_NWDTrainingWebsiteEntities
courseCategoryEntities.CourseCategories.Add(courseCategory)
courseCategoryEntities.SaveChanges()
End Using
End If
Next
When iterating through the loop the code that is:
courseCategory.CategoryID = CategoryListBox.SelectedIndex
works correctly the first time around.
On the second iteration of the loop, it goes to the next selected item however returns the index for the first selected value. How do I return the values of the other indexes selected?
It depends on what ID you need to pass to your database. If it is truly the index of the ListItem in the ListBox, then you would use:
courseCategory.CategoryID = CategoryListBox.Items.IndexOf(category);
That may not be the best approach however. Maybe the order of the ListItems changes, messing up your indexes. You probably want to store the actual CategoryID on each ListItem. The Value property works well for that. You set the column you want as the DataValueField like so:
<asp:ListBox ID="CategoryListBox" runat="server"
DataValueField="CategoryID "></asp:ListBox>
So as you are looping through each ListItem in the ListBox and checking if it is selected, just use it's Value property.
For Each category As ListItem In CategoryListBox.Items
If category.Selected Then
Dim courseCategory As New CourseCategory
courseCategory.CourseID = course.ID
courseCategory.CategoryID = category.Value;
Using courseCategoryEntities As New Eng_NWDTrainingWebsiteEntities
courseCategoryEntities.CourseCategories.Add(courseCategory)
courseCategoryEntities.SaveChanges()
End Using
End If
Next
Fixed the code by deselecting the item in the listbox after it was successfully saved.
End Using
category.Selected = False
End If
This solved my problem.
Actually I spend whole day on the EntityFramework for foreign key.
assume we have two table.
Process(app_id,process_id)
LookupProcessId(process_id, process_description)
you can understand two tables with names, first table ,use process_id to indicate every application, and description is in the seoncd table.
Actually i try many times and figure out how to do inquery: it was like
Dim result = (from x in db.Processes where x.LookupProcess is (from m in db.LookupProcessIds where descr = "example" select m).FirstOrDefault() select x).FirstOrDefault()
First I want to ask is there easier way to do it.
Second i want to ask question is about insert
p As New AmpApplication.CUEngData.Process
p.app_id=100
p.LookupProcess = (from m in db.LookupProcessIds where descr = "example" select m).FirstOrDefault()
db.AddToProcesses(p)
db.SaveChanges()
from appearance it looks fine, but it give me error says
Entities in 'AmpCUEngEntities.Processes' participate in the 'FK_Process_LookupProcess' relationship. 0 related 'LookupProcess' were found. 1 'LookupProcess' is expected.
can i ask is that insert wrong? and is that my query correct?
For your first question:
Dim result = (from x in db.Processes
where x.LookupProcess.descr = "example"
select x).FirstOrDefault()
Actually, you missed some concepts from DataEntityModel, and its Framework. To manipulate data, you have to call object from contextual point of view. Those allow you to specify to the ObjectStateManager the state of an DataObject. In your case, if you have depending data from FK, you will have to add/update any linked data from leaf to root.
This example demonstrate simple (no dependances) data manipulation. A select if existing and an insert or update.
If you want more info about ObjectStateManager manipulation go to http://msdn.microsoft.com/en-us/library/bb156104.aspx
Dim context As New Processing_context 'deseign your context (this one is linked to a DB)
Dim pro = (From r In context.PROCESS
Where r.LOOKUPPROCESS.descr = LookupProcess.descr
Select r).FirstOrDefault()
If pro Is Nothing Then 'add a new one
pro = New context.PROCESS With {.AP_ID = "id", .PROCESS_ID = "p_id"}
context.PROCESS.Attach(pro)
context.ObjectStateManager.ChangeObjectState(pro, System.Data.EntityState.Added)
Else
'update data attibutes
pro.AP_ID = "id"
pro.PROCESS_ID = "p_id"
context.ObjectStateManager.ChangeObjectState(pro, System.Data.EntityState.Modified)
'context.PROCESS.Attach(pro)
End If
context.SaveChanges()
I hope this will help. Have a nice day!
For your first question, to expand on what #jeroenh suggested:
Dim result = (from x in db.Processes.Include("LookupProcess")
where x.LookupProcess.descr = "example"
select x).FirstOrDefault()
The addition of the Include statement will hydrate the LookupProcess entities so that you can query them. Without the Include, x.LookupProcess will be null which would likely explain why you got the error you did.
If using the literal string as an argument to Include is not ideal, see Returning from a DbSet 3 tables without the error "cannot be inferred from the query" for an example of doing this using nested entities.
For your second question, this line
p.LookupProcess = (from m in db.LookupProcessIds
where descr = "example" select m).FirstOrDefault()
Could cause you problems later on because if there is no LookupProcessId with a process_description of "example", you are going to get null. From MSDN:
The default value for reference and nullable types is null.
Because of this, if p.LookupProcess is null when you insert the entity, you will get the exception:
Entities in 'AmpCUEngEntities.Processes' participate in the 'FK_Process_LookupProcess' relationship. 0 related 'LookupProcess' were found. 1 'LookupProcess' is expected.
To avoid this kind of problem, you will need to check that p.LookupProcess is not null before it goes in the database.
If Not p.LookupProcess Is Nothing Then
db.AddToProcesses(p)
db.SaveChanges()
End If
I have an ASP.NET web application (VB.NET) using an Oracle database. On an insert, I need to get the identity of the inserted row back. I am trying to use RETURNING, but I keep getting a value of 1 returned.
Dim strInsert As String = "INSERT INTO L.TRANSACTIONS (LOCATION_KEY, TRANS_CREATOR, TRANS_EMAIL, TRANS_PHONE) VALUES (:location_key, :trans_creator, :trans_email, :trans_phone) RETURNING TRANS_ID INTO :ukey"
Try
If oConn.State <> ConnectionState.Open Then
oConn.Open()
End If
Dim oCmnd As New OracleCommand(strInsert, oConn)
oCmnd.Parameters.Add("location_key", Session.Item("location").ToString.Trim())
oCmnd.Parameters.Add("trans_creator", Session.Item("userID").ToString.Trim())
oCmnd.Parameters.Add("trans_email", Session.Item("mail").ToString.Trim())
oCmnd.Parameters.Add("trans_phone", Session.Item("phone").ToString.Trim())
oCmnd.Parameters.Add("ukey", Oracle.DataAccess.Client.OracleDbType.Varchar2, System.Data.ParameterDirection.ReturnValue)
Dim strUkey As String = oCmnd.ExecuteNonQuery()
When I run the application, the record gets inserted and the TRANS_ID is incrementing but the returned value is always "1".
You're assigning the result of ExecuteNonQuery to the variable, rather than getting the value assigned to the parameter you've created. I believe you want to change the last line to something like this (untested):
oCmnd.ExecuteNonQuery
Dim strUkey As String = oCmnd.Parameters.GetParameter("ukey").Value
That's because the ExecuteNonQuery will return the number of rows affected:
For UPDATE, INSERT, and DELETE statements, the return value is the
number of rows affected by the command. For CREATE TABLE and DROP
TABLE statements, the return value is 0. For all other types of
statements, the return value is -1.
You can see that exist another question that covers the practices for doing it:
Best practices: .NET: How to return PK against an oracle database?
I'm trying to produce a repeater showing amounts of money taken by various payment types into a table.
Payment types available come from a global settings file as an array, I am creating a dataTable by looping this list and extracting sales reports (there might be a more efficient way than this loop, but this is not my concern at the minute).
My question: How do I bind this to a repeater and display it when I dont necessarily know the table column names?
I've tried various methods to give the table a header row and give the columns numerical names from a for > next loop, but am either getting no results, or
System.Data.DataRowView' does not contain a property with the name '7'. < or whatever number
This is where I currently am:
EDIT: JUST REALISED MY CODE WAS AWFUL, SO UPDATED:
Dim paymentTable As New DataTable("paymentTable")
For j = 0 To UBound(paymentTypes)
Dim Type = Trim(paymentTypes(j))
Dim headers As DataColumn = New DataColumn(j.ToString)
paymentTable.Columns.Add(headers)
Next
Dim titleRow As DataRow = paymentTable.NewRow()
For k = 0 To UBound(paymentTypes)
Dim Type = Trim(paymentTypes(k))
titleRow.Item(k) = Type
Next
paymentTable.Rows.Add(titleRow)
Dim newRow As DataRow = paymentTable.NewRow()
For i = 0 To UBound(paymentTypes)
Dim Type = Trim(paymentTypes(i))
Try
newRow.Item(i) = '' GO OFF AND GET STUFF FROM DB
Catch
newRow.Item(i) = "0 "
End Try
Next
paymentTable.Rows.Add(newRow)
THIS EDITED CODE WORKS BUT I ONLY GET ONE ITEM
What I was hoping for would look something like:
card | cash | paypal ... etc (headings row)
£250 | £54 | £78 ... etc (values row)
Obviously there're a million ways this can be done, but this makes sense for my application, which has to be expandable and contractable depending on payment types available and this whole table needs to be repeated for multiple locations (also variable depending on who's viewing, and the number of locations in the system)
No, dont give up but just dont name columns by absolute number with no string before try
Dim headers As DataColumn = New DataColumn("col"+ j.ToString)
I've got the following situation that I need a bit of help with.
I'm pulling through some site locations to a string from a field in a DB using RsData.
strsite = rsData("Site")
Now the issue I've got is that some of items in the table have multiple rows with different sites.
How would I therefore check if multiple values exist and if so set strSite = "Various"
Thanks!
If YourRecordSetObject.RecordCount > 1 Then
strsite = "Various"
Else
strsite = rsData("Site")
End If