I've read through the posts here and can't find any eureka answers so here's what I have.Linq to SQl not propagating a change back to the db.Here's my code. Does anything stand out?The call to dc.GetChangeSet shows 0 changes. What am I missing? I can see the new values from "setting" being set to the cs object properties. SettingID is a primary key in my table and shows as PK in the dbml so that's not an issue.
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I'm having some problems updating the database using Linq...
Public Shared Function Save(ByRef appointment As MyLinq.Appointment, ByRef db As MyEntities) As Boolean
If appointment.id = 0 Then
db.AddToAppointments(appointment)
[CODE]...
So Insert works fine, i have tryed both lines of code for the update with no sucesss... The first one goes ok but no update is performed, the second one throws an exception... Can someone point out what i am missing? I had some internet connection problems...I had to "make it work", so now my update code is fecthing the record from the database, updating and then executing "SaveChanges" method. It works but I am not happy having to query the database to perform an Update... If you have any idea how I could do this without an update.
I have the following code:[code]When I run it, looking at the debugger everything looks okay but when I check the database table it is supposed to be inserting into - the column values (for occupantnum) haven't changed - they are all still null! Not sure if this is related, but note that I've now updated j to explicitly be an integer. I noticed while debugging that wResident.occupantnum was appearing as Type "Integer?" - but this doesn't seem to have made any difference - when I rerun it it still says Type "Integer?"
View 4 RepliesI have a webpage with a form that is used to edit some object. This object contains a Collection of other objects defined like this: Public Overridable Property Employees As List(Of Employee)
On a form I can delete an employee, add a new one or modify existing one. When I click save new values are sent to the server. On a server I check if the user exists. If exists then I modify its values, if it does not exist then I add it. All employees that exist on the server and were not sent are marked as deleted (State changed to EntityState.Deleted). I try to use the following code (dbCollection = database entities, newCollection = collection sent from the form):
[Code]...
This code does not work, because changing to EntityState.Deleted removes the object from collection, and for each loop breaks, since the collection is modified...I know that I can overcome this problem by using a for loop or adding objects to delete to some other list first, but I hope maybe there is a pattern that would make my code nicer.
given this function:
Public Function Search(ByVal StartIndex As Integer, _
ByVal MaxResults As Integer, _
ByVal AccountNumber As String, _
ByVal LastName As String, _
[Code]....
instead of what I expected:
Select count(*) from remitline where lastname = "smith"
What am I doing wrong building up the where clause? I'm using Castle ActiveRecord 2.1
if there is that much of a performance gain in running a LINQ stored procedure versus a LINQ query?
View 1 RepliesI have a listbox on my xaml form that I bound to a List(Of MyType) property. I populated this list like so:
Dim fields As List(Of CheckableFields) = New List(Of CheckableFields)
Using context As ITIPEntities = New ITIPEntities()
Try[code]....
Now I'm at the point where the user selects the fields they want included in a report and I need to iterate over the required fields. This is my linq query:
For Each checkedField In _requiredFields
If checkedField.IsChecked Then
If checkedField.FieldData IsNot Nothing AndAlso checkedField.FieldData.Trim IsNot String.Empty Then[code].....
Example-I have a person class
Public Class Person
Private _fname As String
Public Property Fname() As String
[Code]...
Forgive my ignorance on this.I have this LINQ Query:Dim ngBikersDataContext As New CarBikeWalkDataContext
bikersList = (From c In ngBikersDataContext.Reg_Bikers _
Order By c.L_Name _
Select New Bikers() With { _
.BikerID = c.BikerID, _
.F_Name = c.F_Name, _
[Code]...
with the error "Overload resolution failed because no accesible 'Select' accepts this number of arguments."
Over the "NEW" I get an error " ')'expected."
We are doing a query against an in-memory collection of LINQ data objects. The wrinkle is that we are ordering by a column in a related table whose records have not necessarily been loaded yet (deferred loading:)
Dim oPkgProducts = _
From b In oBillPkg.BillProducts _
Where b.Successful.GetValueOrDefault(Common.X_INDETERMINATE) = _
[code]....
The pattern I'm trying to avoid is checking if a string (normally a control's text value) is null/empty, and if it is, comparing it using Contains to a field in my data. Obviously the field isn't hard-coded into my extension, neither is the object type.What I've got works perfectly in Linq to Objects, but I get the generic run-time error "LINQ to Entities does not recognize the method 'System.String Invoke(GenericQueryHelper.Customer)' method, and this method cannot be translated into a store expression." when using an entity framework model.
Here's what I have:
<System.Runtime.CompilerServices.Extension()>
Public Function CompareAndFilter(Of T)(source As System.Linq.IQueryable(Of T), expressionField As System.Linq.Expressions.Expression(Of System.Func(Of T, String)), compareTo As String)
[code]....
I want my usage to look something like this:
Dim results = repository.Customers.CompareAndFilter(Function(c) c.FirstName, searchText)
I do need to get this running against a SQL database really, as it is filtering results, so I don't want to be doing that in memory.
How can I convert this code LINQ to SQL in C # LINQ to SQL in Vb.net
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How do I add ROW_NUMBER to a LINQ query or Entity? How can I convert this solution to VB.NET?
[Code]...
I'm having trouble porting that last line. I have been unable to locate a VB.NET example. I'm actually not looking for any paging functionality like the example provides, just good old-fashioned Row_Number(Order By X) row index.
How can I convert an object of type System.Data.Linq.DataQuery to System.Linq.IQueryable?I'm working with Visual Basic/Silverlight, and the source code of my query is as follows:
Public Function Get_Cli_Pag() As IQueryable(Of V_Cliente_Pagare)
Dim Qry = From P In Me.Context.Pagares Join C In Me.Context.Codigos On C.Codigo
[code]....
I just upgraded a project from VB 2008 to VB 2010. Before, the project did not use LINQ. I have started implementing it. So, I have updated the target framework from 2.0 to 3.5, and added a reference to System.Core, and imported the namespace System.LINQ to the entire project and also imported System.Data.LINQ into the form I'm working with (because it was not available in the list for Imported Namespaces in the references tab).
It's not throwing any errors now, but my IntelliSense is not working for LINQ stuff.
For example... I write this:
[CODE]....................
Then, if I type S. on the next line, the IntelliSense doesn't grab what it should for S (Only get Equals, GetHashCode, GetType, ReferenceEquals, and ToString, instead of the options I should get like Count, First, FirstOrDefault, etc...). If I Type S.First. then its the same thing, no IntelliSense that lists the available fields for S, just the standard options (Equals, GetHashCode, GetType, ReferenceEquals, and ToString). I should be seeing my column names in my table when I type S.FirstOrDefault.
So any ideas what is going on? When I type the code, for example, MessageBox.Show(S.FirstOrDefault.FirstName), it works perfectly. But it doesn't change the casing of the text (so it would read s.firstordefault.firstname) and no intellisense while doing it. But no errors. BTW - Everything works perfectly when creating a NEW VS 2010 application, it's just my projects upgraded from Visual Basic 2008 that have this issue.
I know that LINQ queries are deferred and only executed when the query is enumerated, but I'm having trouble figuring out exactly when that happens.Certainly in a For Each loop, the query would be enumerated.What's the rule of thumb to follow? I don't want to accidentally enumerate over my query twice if it's a huge result.
For example, does System.Linq.Enumerable.First enumerate over the whole query? I ask for performance reasons. I want to pass a LINQ result set to an ASP.NET MVC view, and I also want to pass the First element separately. Enumerating over the results twice would be painful.It would be great to turn on some kind of flag that alerts me each time a LINQ query is enumerated. That way I could catch scenarios when I accidentally enumerate twice.
I recently switched from VB to C# and have, for the most part, been able to make the transition without too much trouble. Currently I am working on converting a VB.Net program into C# and am having trouble with a couple of code blocks that include Linq.
This is one of the VB.Net lines of code that I am having trouble with:
I have tried to do the same thing in C# like this:
I am getting a compile error on the dt, which says Could not find an implementation of the query pattern for source type 'System.Data.DataTable'.'GroupBy' not found. VS also has issues with the whole into Emailers = group;
I have tried to get this right using examples from my search but have not been able to get it right.
I've finally got around to starting windows phone dev. I'm not very good at it yet, but anyway, I hope you guys understand what I want to do here.From what I've learnt from other programmers, an ObservableCollection can be updated in live time whilst it is databound to an object, such as a listbox. All changes to the ObservableCollection will cause the UI of the object it's databound to update it's items.
So what I'm trying to do, is download a file from my server, parse it with json, then update the ObservableCollection with the new data. However, the webclient doesn't seem to be downloading the new data until the app is re opened!
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I am using a progressbar control in a splash screen.
In my code I am updating the progress bar value with each step -
In Form_Load of the main (hidden) form:
frmProg.UpdateProgress(10, "Checking Connection String")
CheckConnectionString()
frmProg.UpdateProgress(20, "Checking Crystal Reports OCX Files")
CheckOCXVersions()
[Code]....
Is there some event I can use to find out when the progress bar has finished redrawing?
There is something wrong with my codes. I don't know why it isn't updating the records.If I activated the line dt.Rows.Add(newrow) it will just create an error on da.update(dt) line QuoteThe changes you requested to the table were not successful because they would create duplicate values in the index, primary key, or relationship. Change the data in the field or fields that contain duplicate data, remove the index, or redefine the index to permit duplicate entries and try again.But if I deactivate that line, no errors will be occurred but the record won't update.
Here is my code
Dim dt As New DataTable
Dim ds As New DataSet
ds.Tables.Add(dt)
Dim da As New OleDbDataAdapter
[code]....
I have a data grid view bound to a sql server table. What I am trying to do is have changes made in the dgv update in the sql table. I tried to use the Update method of the table adapter but get the following error.[code]....
View 4 RepliesI have a datagridview with a datatable as datasource. If I add a row to the datatable, then the datagridview is not showing the contents.
grdChannel1.DataSource = CreateTable(colChannel)
Private Function CreateTable(ByVal colChannel As MyCollection(Of Channel)) As DataTable
'Create table and add collection into
[code]....
I have 2 row counts if I check the the row counts of the datagridview in the debugging mode.
I have a dictionary of key=string and value=datatable. I use a key to retrieve a datatable and assign that datatable to a new variable. Then I make some updates to the variable. However, I find that the dictionary itself is being updated even though I'm only updating the variable. This causes significant issues when I try to reference the dictionary later. How can I set up my dictionary so that it won't update when I use a value?
dim dt1 as datatable
dt1=dictionary(key)
For row=0 to dt1.rows.count
dt1.Rows(row)(4)=dt1.rows(row)(4)/2
Next row
'at this point, when I look up dictionary(key), the value I get shows all of the original values divided by 2.
I just want to add a DSN if it does not already exist. I am looking at the registry and I know the DSN exists but this code returns False consistently.If(not isnothing(My.Computer.Registry.CurrentUser.OpenSubKey("SOFTWAREODBCODBC.INISQL_Finance", True)),True, False) Once I get past this the next step is to add the DSN if needed.
View 4 RepliesI have a datagridview which i filled with this code:
Dim daProd As New SqlDataAdapter
m dsProd As New DataSet
cmd = New SqlCommand
[code].....
I'm using VS2010 (VB), Framework 4.0 and although I'm incrementing my progress bar value between steps, the progress bar only shows the initial value. I've set the minimum and maximum properties and the initial value, but no luck. Here's a brief summary:
[Code]...
I'm trying to display a DataTable using a DataGridView and a BindingSource as such: (assuming the DataGridView1 and BindingSource1 has been added using the IDE)[code]...
View 3 RepliesWhenever I try to update a row in my database, it works, but as soon as I restart the application, the changed information resets.[code]....
View 10 RepliesI have a dataset which I load three tables into from the database. Each of these three tables are related by the AccountNo. On two of the tables I specify this field as a foreign key constraint with the appropriate cascading flags. However when I scroll through the list of companies with my combo box. Only the one table is having its values change on the form whereas the other tables remain static/unchanged.[code]...
View 5 Repliesworking with data in VB.NET, and the easiest method seems to be XML, since ini isn't supported. So I tried but couldn't find a way to read XML attributes and then replace/update them if needed. So for example I have this XML File:
<?xml version="1.0" encoding="utf-8"?>
<Entries>
<Entry1 font="Arial.ttf" R="255" G="255" B="255" effect="Stroke"></Entry1>
<Entry2></Entry2> - In the same format
</Entries>
How do I load those as strings, for example I want to write them to a file later, and I use the code:
sw.WriteLine("Font")
But instead I want to load the attribute from Entry1, instead of loading it from pre-defined variables. one more thing I want, when the user clicks a button to update an attribute (Font for example) to the current textbox text.