I'm trying to find a way to have the DataContext available from within Entities.
I want to do something like this:
partial public class MyEntity
public DataContext as MyDataContext
private sub OnLoaded()
[Code]....
This should be pretty easy, but it throws VS2008 for a serious loop.I'm trying out WPF with MVVM, and am a total newbie at it although I've been developing for about 15 years, and have a comp. sci. degree. At the current client, I am required to use VB.Net. I have renamed my own variables and removed some distractions in the code below, so please forgive me if it's not 100% syntactically perfect! You probably don't really need the code to understand the question, but I'm including it in cas.
I have a very simple MainView.xaml file:
<Window x:Class="MyApp.Views.MainView"
xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
[code].....
I have 20 labels on my Excel VBA user form. I have named them as lbl1, lb2,..... lbl20. I need to set the caption of all the labels retrieving from the excel sheet. for e.g.,
Dim objthis as object
Set objthis=thisworkbook.sheets(1)
lbl1.caption=objthis.cells(1,1)
lbl2.caption=objthis.cells(2,1)
.
. so on till
lbl20.caption=objthis.cells(20,1)
I felt this was crazy to write 20 lines of code for just captioning labels. If I can write it this way
For i = 1 to 20
lbl & i = objthis.cells(i,1)
next
I know this is incorrect and wont work. May be I am near to finding out the approach or may be its not possible.
I'm going through an XML file of articles and the journalist(s) that wrote them. As we are adding the articles into _Data our datacontext we may come across a journalist that needs adding so we do this: [code] However subsequently we may come across this same journalist again and nothing is returned when we do this: [code] So it uses the code above again to insert the same journalist again.Once all of our inserts are done we do a submitchanges. At this point it has a head fit:INSERT statement conflicted with COLUMN FOREIGN KEY constraint 'FK_ articles_ journalists_journalists'. The conflict occurred in database 'blah', table 'journalists', column 'id'. The statement has been terminated.From looking through the sql generated in sql profiler you can see that it is trying to add some journalists more than once, this will fail as the name must be distinct. The subsequent records that are trying to be inserted with these journalists are failing as the journalist wasn't updated.Surely if I have a collection of journalists, add some to it and then look in my collection I should see all of them and not just the original ones.
View 3 RepliesI've got a class that closely resembles one of my entities (I use the class for JSON de/serialization because the entity fails conversion to JSON, one of the known gotchyas of JSON + MVC).Once I deserilize a JSON string into my object, is there a way to automatically update the associated Entity model instance. The property names are the same.
'myDeserialized is the deserialized JSON object coming over the wire
Dim entityInstance As DLL.Person = db.getPersonById(myDeserialized.id)
myDeserialized.update(entityInstance)
[code].....
I have the following query:
Dim queryStudent = (From p In dbContext.Residents _
Where p.people_code_id = people_id _
Where p.year = year _
[code].....
in Old vb/VBA, I am accustomed to doing THIS when I instance a form object (as in "pop-up"):
Private WithEvents SomePopUpForm As Form_PopUpForm
Private Sub cmdEdit_Click()
Set SomePopUpForm = New Form_SomePopUpForm
SomePopUpFOrm.Visible = True
End Sub
[Code]...
I am trying to build a survey engine from an existing database design which is like this.
[Code]...
The line Order By Key.RecordOrder throws a null reference exception and I can understand why. Can someone advise on how to resolve this by just modifying this one query? I am fairly new to LINQ and the necessity to write this project
[Code]...
I want to update an entity without loading the entity from the database first. I've accomplished this but only by knowing all of the entities properties and then using the "attachto" method. My issues is i don't want my app to need to remember all of the properties. Example:
[Code]....
Entity Splitting: one class, two or more tables.Here is how it is done in C#, but I need to get it working in vb.net.One more thing: the class name and table columns do not match, so I have to be able to map that out, too.I have to get this to work this way because the place I'm working at right now is a vb.net only shop and the database schema is fubar, but they have so much (millions) of lines of code done directly against the database in both asp classic, vb.net, AND asp.net webforms that changing the schema right now is not realistically possible.
protected override void OnModelCreating(DbModelBuilder modelBuilder)
{
modelBuilder.Entity<Post>()
.Map(m =>
[code]....
I am trying to jump from ASP Classic to asp.net. I have followed tutorials to get Entity Framework and LINQ to connect to my test database, but I am having difficulties figuring out ExecuteQuery(). I believe the problem is that I need an "entity class" for my database, but I can't figure out how to do it. Here is my simple code:
Dim db as New TestModel.TestEntity
Dim results AS IEnumerable(OF ???) = db.ExecuteQuery(Of ???)("Select * from Table1")
From the microsoft example site, they use an entity class called Customers, but I don't understand what that means.
I am trying to create a generic typed class, but am running into a problem. Here is my basic class definition:
public class QueueObject<T> where T : System.ServiceModel.DomainServices.Client.Entity
{
public string LoadingMessage { get; set; }
public System.ServiceModel.DomainServices.Client.EntityQuery<T> Query { get; set; }
}
I am trying to add instances of this class to a queue
private Queue<QueueObject<Entity>> _queue;
this._queue.Enqueue(new QueueObject<MyEntity> {Query = MyContext.GetMyEntitiesQuery(), LoadingMessage = "Loading some stuff"});
This doesn't work. I get an error saying that QueueObject cannont be converted to QueueObject. I don't understand because MyEntity inherits from Entity.
Public Class QueueObject(Of T As System.ServiceModel.DomainServices.Client.Entity)
Public Property LoadingMessage As String
Public Property Query As System.ServiceModel.DomainServices.Client.EntityQuery(Of T)
End Class
[code]....
I have a context menu on my DataTemplete for a list box, and that menu will contain links to Favourite and Retweet the tweet (the menu item) But I don't know how to get the information about the Tweet in code. I am trying the following Line:
[Code]...
I have some data in my Linq.DataContext.I had succes in converting it to an XSD - Schema, using the following code:
Dim changeset As System.Data.Linq.ChangeSet = c.GetChangeSet()
Dim objDic As New Dictionary(Of System.Type, List(Of Object))
If Not changeset Is Nothing AndAlso Not changeset.Inserts Is Nothing AndAlso Not
[code].....
I am setting my viewmodel as datacontext in my xaml but I override it to my view to make few functions work however to achieve the visibility on some grids and I have a property in my VM can I override my datacontext back to my VM? If so how? I have a stackpanel that has datacontext overriden as my grid and within that stackpanel I need to change the datacontext for a button.
View 1 RepliesI would like to know if its possible to discard changes of only one record of only one table in datacontext. I use databind to bind my controls on a form. I modify one record at a time. after the modification, the user have to hit save button to validate. But he can hit cancel. I would like that the cancel button discard all the changes that the user has done. Is it possible?
View 3 RepliesI asked a question earlier where I was told a simple way to "bind data to objects" is to just run a SqlConnection(connectionString). The response also included a comment saying I could get fancy with L2S and Entity Frameworks, so I looked deeper into those. It seems all you have to do with the DataContext object is point to the database. Why would SqlConnection be a benefit? What is the difference (or pros/cons) of using either one of these? Is one more "standard"? Is one more modern?
View 1 RepliesHow to bind a textbox in design view to a LINQ to SQL datacontext class?
View 3 RepliesUPDATE: See the bottom of this question for what I did to solve the problem.I'm trying to understand how the ItemsSource and DataContext properties work in a Silverlight Toolkit DataGrid. I'm currently working with dummy data and trying to get the data in the DataGrid to update when the value of a combo box changes.
View 2 Repliesso im trying to do this project, and it gives me a a data file, and asks me to use stream reader to put it in the combobox, and when i click the selected items from the combo box, it fills in the textbox's with other information i retrieved from the datafile...Does anybody know the solution?? heres what i have so far(option strict must be on) Private Sub Form1_Load(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles MyBase.Load
[Code]...
this gets all the Item names from the data file to appear on the combobox... now if i knew how to get the other information to appear in the textbox's when i clicked on it,
I have an object that may have been inflated via a plain old DataContext, or may just have been new-ed up with just its .ID property set. There's no way to know for sure. I'm looking to rehydrate the entire object from whatever is in the database. If the object was new-ed up, I can call .Attach() on the table object and refresh from the Data Context with no trouble. But, if the object was already inflated from the DataContext I get the error: "Cannot attach an entity that already exists.". There's no timestamp field or anything like that - just an integer primary key being used to control the rehydration. I'd like to know if there's a way to conditionally attach. Here's the code - it works the way I want it to, but this seems a hackish way to go about it:
' myDC is a shared instance of a vanilla DataContext...
' myObj is an instance of a linqed-up `SomeLinqObject`
Dim tbl = myDC.GetTable(Of SomeLinqObject)()
[Code[,,,,,
I am preparing to deploy a web service that uses SqlConnection primarily as its means to get to the database, and I am adding some new methods that use a DataContext instead of thatand the default constructor and DBML file would use a connection string refering to my development machine (I believe...)
View 1 RepliesI am new to WPF and the MVVM design pattern this month, and more than a little out of practice in general. To learn, I've been playing around with textboxes, rectangles, and ways to display them in a window. I began with Ashley Davis' excellent "Simple Drag Selection in WPF" tutorial, which walks through creating a view model for a collection of rectangles, binding a listbox to said collection, and styling the listbox with a canvas, creating a data template for the rectangles, as well as basic "rubber band" selection logic.
I have since built on this tutorial to improve the drag selection so that it behaves much more like selection does in windows explorer, and to allow resizing the rectangles from the corners or edges.All was well until I changed the MainWindow.xaml in an effort to include a column on the side for various buttons and controls, thus moving the "editor surface" grid from inside a 1x1 grid on the main window to a column of a 1x2 grid, moving the data template to the grid's resources (since it will be the only element in the window that needs it). As soon as I did this, subroutines that I wrote which interact with the listbox started misbehaving--rubber band selection no longer works. There's no visual indication that listbox items are being selected (they were highlighted previously), and interrogating listBox.SelectedItems.Count after a drag-selection mouseUp event returns a zero.
After some experimentation, reading many questions on this site and sections of my WPF Unleashed book, and going over the msdn databinding overview, as of this morning I still cannot find my mistake(s). I believe it is a data binding mistake or incorrect data context.Some details about the view models involved:
DataFieldViewModel
...implements INotifyPropertyChanged and exposes properties for its (in this case a rectangle and a textbox) X,Y position, width, height, visibility, and selection status (a way to track it across several rubber band selection operations)
PageViewModel
...implements INotifyPropertyChanged, and has among other things an ObservableCollection of type DataFieldViewModel, called DataFields, and exposes it as a ReadOnly Property.Here's a look at MainWindow.xaml.vb and one of the broken subs:
Namespace EditorUI
'
' The main window of the editor.
[code]....
I have this list (Just a typical .net list) and I am adding a bunch of UI Items into it, the list is then taken for a Sub which goes through it with .getenumarator and While loop. Now the question is how are my items retrieved from this list?
View 2 RepliesI tried the following code which doesn't throw an error but it doesn't show as well in textboxes:
Try
cnobj = con.cn
cmd.Connection = cnobj
[code].....
I'm trying to check if a bit retrieved from database is true or false but i have always the error IndexOutOfRangeException no matter how i get the value.
[Code]...
I would like to read values set in a string that's retrieved from the Web, I've already got the string in a string called Webdata.The string is like so...
"Info" {
"Name" {
"Name1""Value1"
[code]....
I need to set Value1, Value2, Value3 as strings that I can use.
I retrieved data from access in vb10 between two dates and here is the code for dat:
Imports System.Data.OleDb
Public Class Form4
Dim con As OleDbConnection
[code].....
I have a database in my app which loads and displays some information on a form by binding the Comboboxes and Textboxes. However, I need to get some of the other values from the database for calculations before they are displayed on the form and I can't seem to find out how to do this.I could bind a couple of Textboxes to the database and then use those values to calculate, but it doesn't seem like a very efficient way of doing things.The dataset is created using the wizard and the controls are linked in the UI.
Please bear with me, I'm still a noob.
I have a LINQ to SQL DataContext with all my tables and all my stored procedures in it. Let me first start off by saying that we are upgrading our project from an access project to a WPF project. So in the Access project you could set a forms datasource to a stored procedure and edit and add new information. So in my WPF project on the page load I call my stored procedure to return an ISingleResult and then call a function to set the binding on every single textbox on the form. One is there an easier way to do this and two what if I want to add a new record since the textbox's are binded to an ISingleResult?
View 2 Replies