Updating Child Collection Of POCO (adding/updating/deleting) In Entity Framework 4.1?
Jan 25, 2012
I 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.
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Feb 18, 2011
Ok... So I have created my model using EF4. Great!I then turned off the code generation and downloaded this extension: [url]...Ran it, and it generates all of my classes. Is that all I have to do? It seems to work, my repositories get to the objects and persist to the DB.
[code]...
Where does the service layer fit in?What about the AutoMapper? Do I even need to use that now?Dependency Injection?
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Feb 12, 2012
My project involves making a table database that displays student number, surname, first name, homeroom, and grade avg. Through SQL commands, there must be functions to add, update, delete, search by field, and save records to the database.I have already set the database up just fine and displayed it in a DataGridView. Through the DataGridView, I was able to go to the "Add Query" area, and I successfully made the queries necessary for searching by field. However, when I try to do anything other than a search using the query builder (ie start my SQL command with INSERT INTO or DELETE FROM), I ultimately get the message "Failed to get schema for this query"For example, this SQL code (to add an entry to the database) worked when I was in the Query Builder (and the entry that it made is still in the database), but when I finally tried to confirm it, I got the "Failed to get schema for this query" message.Being unable to add entries to the database this way, I tried to do it with textboxes on a form. Each textbox will have one of the fields, and at the click of a button, they would be put into the table. My code is below. I do not know what is wrong withit. When I run it, my fields do not appear on the DataGridView immediately, but I must run the program again to see it. The time after, the entry is gone. So I am not sure how exactly such entries are to be saved.
Private Sub Button1_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles Button1.Click
Try
[code].....
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Jun 16, 2012
I have designed a form which contains a listview(to see the list records) and textboxes (used for adding or updating).an already save record into table using this
cmd.Connection = con
cmd.CommandText = "INSERT INTO student_info_tbl VALUES('" & txtUserId.Text & "','" & txtFirstName.Text & "','" & txtMiddleName.Text & "','" & txtLastName.Text _
[code].....
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Mar 7, 2012
I have 2 tables in my DB: "Competitions" and "CompetitionAnswers". Each competition will always have 3 answers. I want to be able to edit the Competition and CompetitionAnswers for the same view. I have managed to get the view to work by using editor templates So this is my editor template:
[Code]...
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Apr 9, 2011
I have the following code:
' Now retabulate the current occupancy.
For Each row In assignments
Try
[code]....
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Jun 21, 2011
I have a problem when updating an entity (User) in my application.
The entity is located in session when the user has been logged. So I made it:
Dim u as User = (From x in ctx.Users).First()
Session("user") = u
[code]...
I got the follow error:
An object with a key that matches the key of the supplied object could not be found in the ObjectState Manager.Verify that the key values of the supplied object match the key values of the object to which changes must be applied.
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Mar 7, 2012
i have doing a project using vb.net which a function like insert,update and delete data from database including image. i have successfully insert the image what i did for that is i copy the image to a location named image in current directory of the system and save the path into the database according to the user id.now the problem is, when user need to update the details the image won't update i have an error and when user wants to delete the details, the details in the database deleted but the image not.
Codes:
insert data
Private Sub btnSave_Click(ByVal sender As System.Object, ByVal e As System.EventArgs)
[code]......
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Jun 17, 2012
I am getting the attached error while updating or deleting the records. [code]...
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Oct 11, 2009
I'm trying to update a value in.... errr, one of the variables in my structure (don't ask me to use the correct terminology because I don't know it). I'm doing this during a Select/Case ..
[Code]...
This is just an example, I've stripped out most of the real code. Anyway, the point here is that when I set Client.SendPhase to 999.... then next time I come back to this loop it's still set at 0. Why doesn't it retain the value I've given it?
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Nov 5, 2010
im having a problem on double execution, this is a part of audit trail on my system, the DELETE FUNCTION is working, but it aint updating, im getting an error - it says that "Syntax Error on update statement" on i tried to manually query it on my access and it is working, i bold the statements that affectes the UPDATE function
Dim burahin As String
burahin = MsgBox("Are you sure you want to delete a customer from the database", vbOKCancel + vbQuestion, "Administrator")
If burahin = vbOK Then
[code]....
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Jun 15, 2010
For school i have made an application in VB (Express 2010, .net v4) and when i try to run it at school it says that the .net framework needs to be updated.
IS there anyway of not updating the framework but still allowing the application to run?
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May 11, 2009
I have a datagridview that I am binding to a collection. What I need to do is process each object in the collection (send quotes to our customers), and then display the items status in the grid. Then once the collection is completely processed clear the grid of items for the next round. I am binding to the collection with .DataSource = collection.
My Question:What would be the best way to update the grid as the collection is processed one object at a time.Initially I had thought about storing each item in a database table and then bind the grid to the table. Then as I processed each record, update the record and rebind the grid. The problem I had with that method was that I would be constantly writing and deleting data from the same table. That seemed unnecessary vs just using a collection and updating the collection.
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Mar 15, 2012
I start my project in vb.net backend is sql server i have completed my design now i start my coding but i am confused for connectivity code whether i used dataset or datable which is good? please give me best connection code for retriving,updating and deleting data from database..
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May 6, 2012
I am using a Dim All_PriceLists As System.Collections.ObjectModel.ObservableCollection(Of BSPLib.PriceLists.PriceListPrime) where PriceListPrime implements Inotify for all properties in it.
I bound the All_PriceList to a datagrid as DataGrid1.ItemsSource = All_PriceLists but when I do All_PriceLists=Getall() where Getall reads and gets the data from the DB, the datagrid is not updating.[code
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Jul 8, 2009
We are working on an asp.net 2.0 web app that emails users an ical to save to their outlook 2003 calendar. We noticed none of the code to update or delete an item seem to work even though the ical 2.0 spec supports it. We are curious if Outlook 2003 just ignores this?Does Outlook 2007 act differently?We have situations where an event may change or be cancelled which fires off an email notification but the updated ical just adds a new event, it nevers deletes and or moves the original.
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Apr 11, 2009
I have tried everything.but im not able to insert updat and delete the excel file..im able to connect the excel sheet.the connection also seems to be opened...here s my connection string:
Dim sConnectionString As String
Const kunal = "C:"
sConnectionString = "Provider=Microsoft.Jet.OLEDB.4.0;" & _
[code].....
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Mar 24, 2011
How can I do this, this what I got so far.
Dim ClassID As Integer = 1
Dim da As New SqlDataAdapter
Dim con As New SqlConnection("Data Source=.SQLEXPRESS;AttachDbFilename=D:Database
[code].....
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Mar 13, 2009
I am getting a System.Data.InvalidConstraintException" ForeignKeyConstraint CompanyPasswords requires the child key values(-1) to exist in the parent Table. When saving updates to the parent and child tables.My parent table consists of 3 columnsCompanyID (auto increment, pk)Company NameURLMy Child table consists of 4 columns PasswordID (auto increment, pk)CompanyID (fk)User NamePasswordHere is all the code on the form
[Code].....
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Nov 26, 2011
I have a MDI app in development that uses parent-child datasets. My problem is when I update a dataset on one child form I then need to update the dataset on another child form. I know the dataset update has been commited to the source as when I reload the second child form the changed values are displayed.
[Code]...
Main.CarTableAdapter.Fill(Me.RCCarV2DataSet.Car)Unfortunately when I close the form that executes the above code the "Main" form which is still open should display the new values in the bound controls but it doesn't. The only way I can get the changes to display is to close and reload the "Main" form.
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Jan 11, 2011
I have a situation where a database table is updated with records inside a loop. Every record in this table has a parent child relationship with another table. This child table is also updated subsequently inside the same loop.I am creating the datatable for Parent table and adding records inside the loop, but committing the records in the database (using SqlCommandBuilder) outside the loop only once.
Inside the loop I am also calling the function for updating records in the child table. Because the adaptor and datable objects are created inside the child table function, I need to commit records in child table inside the function only. So this happens before commit of parent table. Because there is a PK-FK constraint in the database, an error is generated.
Simplest solution would be to bring all code inside one function. But I don't want to do that. Besides this parent child relations can go upto any levels.
[Code]...
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May 13, 2010
c# - Are Microsoft Entity Framework and ADO.NET Entity Framework (.edmx) the same?
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Jul 20, 2009
I am using a number of tables on my application and two of which have a foreign key constraint I have set between them. When I change the account number on the main table via a combo box all of the relevant information for that table on the form is updated accordingly. However, the child table which has a foreign key reference to the Account Number of the main table is not updated when the acocunt number is changed. I have set the update to cascade in the references but still am having issues.
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Apr 24, 2012
I am trying to add and update data in a db from a DataGridView. I have a save button that runs this code. The code works fine. It figures out which rows are new and add it into the DB and which rows are updated and updates them in the DB. BUT if you press the button again it will add the new row in again. it does not mark the new row as one that needs updating when the button is pressed again
Dim recall As New stLib.clsRecall
Dim rulesRow As DataGridViewRow
For Each rulesRow In DgRules.Rows
[Code].....
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Apr 22, 2009
OK - I have worded this search 40 different ways and I seem to be lost here. Every example I find seems so happy that you can easily drag and drop a datagrid and let the user fill it in -- then they stop! I know how to do everything I am asking through LINQ. That obviously won't translate here. I really should have learned ADO.NET first, then LINQ, but NOoooo... I need to know how to do the following in .NETCF (Windows Mobile 5) using a SQL CE database on the device.
Add a new record and populate some or all of the fields with data I supply. I don't need to add a record to a datagrid - sometimes the user will not even see the record. How do I add a new record -- put data into it and save it? For example: Create a new delivery record, say, and have the program store the date in one field and a number in another field. Search for a record, then update data in it. Again, using LINQ I can do this easily -- I cannot for the life of me find any examples of doing it without it.
I can find lots of examples of populating a grid of databound fields, letting the user make changes then saving it out. I don't need to do that. Say I need to search for the one record that meets a criteria (customerID=10 and orderID=1234), then when (if) that record is found, update a field in it.
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Feb 7, 2009
I know that when I add a record to a table through a binding source using a binding navigator - it completely handles the IDENTITY PK (it's bound to a textbox and you can see it immediately).
Now I'm trying to do this differently in another part of the program - here I only have a BINDING SOURCE - that's bound to a DATAGRIDVIEW.
I put a new record into the DGV like this
Private Sub vendorfilesDGV_DragDrop(ByVal sender As Object, ByVal e As System.Windows.Forms.DragEventArgs) Handles vendorfilesDGV.DragDrop
If e.Data.GetDataPresent(DataFormats.FileDrop) Then
[Code]....
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Jun 16, 2009
I have recently built an N-Tier app using VB.Net 2008. The application is based on Beth Massi's tutorial at [URL] I am trying to incorporate a datagrridview control on a Parent form - one parent (father and mother) to many children. For example,
[Code]...
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Jul 22, 2009
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]....
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Dec 14, 2011
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]....
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Jan 16, 2011
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.
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