Entity Data Model & DataGridView - Creating New Objects?
Mar 30, 2010
I'm pretty new to the EDM, so bear with me. I have a windows form that has a DataGridView on it that's bound from the EDM I created. I figured out how to update my changes fine, but it's when the user creates a new row that I'm having a problem.I tried numerous ways and many google searches, but came up with nothing so far.
[Code]...
Error (occurs when calling _Context.SaveChanges()): Store update, insert, or delete statement affected an unexpected number of rows (0). Entities may have been modified or deleted since entities were loaded. Refresh ObjectStateManager entries.
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May 6, 2010
in a new project I thought I would try to integrate the new Entity Model Framework, but am having some issues/problems and would like to know if there is a solution or workaround that will let me insert a record into a table that has an identity property.At first I thougth it might simply recofnize the storedprocs that I have for insert/update/delte actions, and was a bit discapointed when generating the model ignored all my stored procs. So I thought wll heck maybe it just generates a nice insert method for me. Lets see.So I referenced my model and found that for the table (entity) there was an insert action (method) that had been generated, however what i found is that it explicitly added the primarly key field - which was based on an identity property and will not accept an explicit insert value.So I guess 2 questions
1. How do we work with identity properties
2. How can we take advantage of the performance and securtiy advantages that stored procs offer with SQL server?
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May 22, 2012
I am working on a silverlight project in which i am using the entity data model. I have a consol application in the same solution through which i am creating the database table at runtime. Now when i moves to silverlight page i need to Communicate (load
data from newly created tables).But problem is that without updating the model how i will able to communicate with that table at runtime using entity framework model.
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Dec 1, 2011
I have a misunderstanding somewhere with the Entity Framework. This code is from my unit testing:
Public Sub UpdateRosterLinkTest()
Dim target As PlayerAdmin = New PlayerAdmin()
target.PlayerAdminManager = playerAdminTestManager
target.Team = playerAdminTestManager.GetAirForceMensBB()
[code]....
When I run this code, I can see the changes saved to the SQL Server this pulls from (RosterLink = Roster Link, like I set in the unit test).However, my unit test is failing, because team.RosterLink is still Nothing. The function GetAirForceMensBB() returns the Team with TeamId = 12434:
Function GetAirForceMensBB() As DAL.Team
Return (From team In Container.Teams Where team.TeamId = 12434).SingleOrDefault
End Function
I'm sure I'm using the entity framework incorrectly and it probably has something to do with the fact that I am calling the PlayerAdminTestManager in different places, but I don't understand why. Although, I set the PlayerAdminManager to be the PlayerAdminTestManager. PlayerAdminTestManager extends PlayerAdminManager, fyi.Why is team.RosterLink not showing the update from UpdateRosterLink?
EDIT:Container is my ObjectContext. This is how I access the information stored in the database.Container.Teams represents my Teams table.
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Feb 6, 2012
I am using MS Visual Basic Express 2010 and trying to generate "ADO.Net Entity Framework" entities from an existing local SQL Server Express database.
Using the "Entity Data Model Wizard" I am asked to configure a connection. Here I prompted to choose a "Data source" and given two options 'Microsoft SQL Server Compact 3.5' and 'Microsoft SQL Server Database File'. I select the second option.
I'm then prompted for connection properties, I have to enter the "Database file name (new or existing)". Here I browse to the SQL server database file of interest (found using Management Studio Express) namely[code]...
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Jul 13, 2010
Whilst going through the "ADO.Net Entity Data Model" wizard, I select 3 tables from within a Database to add to my edmx file, and when the file is generated only one of the three tables is there. There was no error or warning to explain why the other tables haven't been added. If I try and add one of the failing tables on its own, again, nothing happens.I am using VS 2010, SQL Server 2008.
Any ideas as to why these database tables are failing to create? I realise there isn't much detail to this question, but there isn't much detail to the situation - It really is a database with 3 tables, of which 2 are failing to create through the wizard with no error.
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May 1, 2012
We need to store a list of data we pull from another table that relates to one of our models. (We are too deep into build to add this relationship to our DB where it should be.) When we attempt to load this list in a property of the model that needs it.We load this list into a dropdown in a view. The error occurs trying to load this list into the model in the controller. The true caveat is that we have a unique dropdown list for each record in our table in the view.
Our Class:
Public class OurModel
public property ID As Integer[code]....
Error: LINQ to Entities does not recognize the method 'DB.ModelTable get_Item(Int32)' method, and this method cannot be translated into a store expression.
UPDATE: The issue appears to be that LINQ is trying to do something with a the DBContext of a query I do previously in this controller. The error is referencing DB.Employee not DB.Position which is what I am querying.
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Apr 6, 2011
I have two properties ("FIRST_NAME" and "LAST_NAME") I need to access as a single property (e.g. "FULL_NAME"). Is there a way for me to add a property to my entity model that contains the combine value of FIRST_NAME and LAST_NAME?
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Jun 9, 2012
In entity framework we can use 3 approaches model first , code first , database first but each one of them needs manual hand touch(means creating database or create model or write the POCO class codes or entity class codes) before proceeding to the next step ( using EF in context ).What if I want to create database and tables and table relationships programatically and still want to have to features of EntityFramework 4.3.
To be more specific ,from this example http://support.microsoft.com/kb/307283 we can create database , tables and everything using SQL command but we can't have the advantages of entity framework. So if we want to have that what should we do? To give the ability to create dynamic table fields those steps will not be sufficient. In all 3 steps database , table and table columns are fixed. There is no way that a user can create new tables or columns dynamically. http:[url].... in this post , it shows how to create manual db, tables and etc using SQL but it is based on ADO.NET but I want Entity Manager to do that.
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Oct 26, 2011
I have about 20 different report tables in my Entity Data Model that all have a few common fields (like start_date and end_date). When my reporting application pulls data for a given report, the first thing I do is filter the table for today's date. This means I have code blocks similar to this throughout my code (VB)[code]...
Is there a way to create a single generic function that can apply some logic to different objects and return that specific object instead of a generic one? Alternatively, is there a way to cast the return value back to the specific entity object type?
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Aug 15, 2011
I am using the O/R Designer to create entity classes in VB 2010. I am observing different results for different database tables that I can't explain and more importantly, can't replicate the results that I want.Using server explorer, I have dragged a number of tables on the O/R designer surface, thereby creating the entity classes.
I have saved the project and can access the various entity classes in my project code. I first noticed a difference when changes made to object instances from some tables/entity classes appeared to persist while changes made to object instances from other tables/entity classes did not persist. These object instances are created, accessed, and changed using the exact same code patterns except for the object, class and table names.
I have been looking to see if there are any differences between the way in which the entity classes are treated, either in my code, in server explorer, or in the O/R Designer. I cannot find any. The properties of the entity classes indicate that all of the classes use the runtime methods for insert, delete and update. As far as I am aware, I have not knowingly made changes to these methods.
The ONLY difference that I find is in the file NameofClass.designer.vb. This is an automatically generated document. The partial class of those objects that appear to persist changes contains different code from that of other partial classes where changes to objects do not persist.In the declarations section of this partial class, the following lines appear:
<Global.System.Data.Linq.Mapping.TableAttribute(Name:="dbo.OrderofBattle")> _
Partial Public Class OrderofBattle
Implements System.ComponentModel.INotifyPropertyChanging, System.ComponentModel.INotifyPropertyChanged
[code]....
If I am right then I want to enable persistence in my other classes by causing this additional code to be generated for them. But how? why the code for this one class hase been generated differently than for all the others (actually it is this way for 2 out of about 15 classes). What setting or or selection do I have to make to enable this code to be created for my other entity classes during the automated process?
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May 13, 2011
How would I create my custom Role class based on that autogenerated class? I have read a few articles on the net but I am still lost. Can someone please show me how to do this, and what I must import(using visual basic). I want to add some validation to the string property where Role1 cannot be more than 50 characters.
Autogenerated class
[Code]...
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Jun 28, 2011
Im a newby in creating programs using vb.net. Currently 'm creating an program that will display array data to datagridview. Can somebody help me how to do it?
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Mar 31, 2011
I am creating a reporting app that pulls information off of a Sql database and populates the data in a datagridview control (DVG). I am using tab pages (Tabcontrol), and I have about 10 tabs with within the control. What I have done is created a dynamic control that will populate in each tab page once the tab is selected. I am using a split container and in my split container.panel 1 is where all my buttons and search functionality will be. In my split container.panel2 to is where the main DGV control will be. I have got this to function properly, however now I am unable to add anything to my split container.panel1. I would like to add diffrent labels and buttons in the panel1 one without putting another panel on top of the split container.panel1, and also if i do this when I resize my container the panel will just sit there. I am using the selected index changed event to get my split container to show in each of the diffrent tabs
Private Sub searchTab_SelectedIndexChanged(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles searchTab.SelectedIndexChanged
searchTab.TabPages(searchTab.TabPages.IndexOf(searchTab.SelectedTab)).Controls.Add(splitContainer1)
[code]...
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Mar 29, 2012
fetching data from simulated model
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Jul 8, 2009
I am working on a project. Part of my project requires me to capture data, for example, email address, from certain rows/columns of a datagridview(form2.vb) and displays them in a textbox on another windows form(form1.vb) with a click of a button(Add Contact button). The problem is the datagridview on my form must be able to display databases by making a connection to Microsoft SQL Server 2005 but so far, i have not been able to do that. I have seen many codes with regards to my problem but i do not know how to implement it.
Below are my codes that i have written so far. My program's limitations are not being able to display databases from Microsoft SQL Server 2005 so i created the statement below to add columns and test my codes.
DataGridView1.Columns.Add("CustName", "CustName")
DataGridView1.Columns.Add("Email", "Email")
[Code]...
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Feb 25, 2011
in the sense that MVC does not complain about my protected inner abstract Metadata class, and the model validation still works:
Partial Domain Object, generated by a tool:
Partial Public Class SampleDomainObject
Private _id As Integer
[code]....
I did this because I didn't want to have to implement actual properties with backing fields, getters, and setters in VB.NET for the Metadata class to keep the maintenance to a minimum (I'm on .NET 3.5, no auto-properties for me).What I'm worried about is that having a protected abstract inner class could be confusing to others using this domain object outside of MVC (my domain objects are part of a shared data access framework).
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Jul 13, 2010
I use Visual Studio 2010 and SQL Server 2008 R2. I have created an Entity Model in a class library which I have referenced in a VB Winforms project. I created a data source in the project based on the entity model in the dll. However, all columns in the data source are listed in alphabetical order instead of the native order from the SQL Server database. I cannot locate the cause of this as much as I try.
This might not seem a huge problem, but it is costing me valuable time in rearranging controls dragged to forms and reindexing their tabstop indexes.
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Apr 10, 2011
1) Add a Private variable named _area2) Associate the _area variable with a Property procedure called Area3) Change the CalculateArea method to a Sub procedure. The method should calculate the area and then assign the result to the _area variable.4) Include a parameterized constructor in the class. The constructor should accept one argument: the side measurement. After using the Public property to initialize the Private variable, the constructor should automatically call the CalculateArea method.At this point I believe I've completed the first 2 steps for the Square method, but I'm not sure where to go from therHere is my code for the Square class and the Main Form, in tha order:
Public Class Square
Private _side As Integer
Private _area As Integer
[code].....
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Nov 18, 2009
1. Write a Visual Basic Console Application which creates two DateTime objects. One DateTime object should be used to store a value for date purchased. The second DateTime object should be used to store a value for date paid. See below for more information.
2. Assign values to the two DateTime objects.
3. Use the toString method to display the two DateTime objects.
4. Compare the two dates to determine which date occurred first.
5. Compute the number of days elapsed between the two dates.
6. If the date purchased occurred before the date paid, display: The number of days required to receive payment was ________. Replace the _________ with the number of days computed between the two dates.
On the other hand, if the date paid occurred before the date purchased, display: The number of days this order was pre-paid was _______. Replace the _________ with the number of days computed between the two dates.
If the two dates are identical, display: The payment was received on the same date as the purchase.
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Jul 27, 2011
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]...
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Jul 25, 2011
I'm having a problem at the moment developing my application. What i need to do is find out how many modems they are connected to my system and send data to each one in turn. I have the programme working for one modem at the moment.
So I can send data to a modem that i specify, for example a modem on COM port 1. I have functions already that will give me a list of COM ports that I need to open.My problem is that i want to dynamically create a new modem object along side existing modems and store them in a collection.
[Code]...
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Aug 27, 2010
I'm wondering on how you would go abouts instantiating a class that contains other complex objects. for example an Payment Class which has Date,Time, etc.. and it also holds a reference to a paymethod object which has id,Type,Description etc.. How do you instantiate the payment class with all the other objects without one or the other failing, how do you create the payment class which doesn
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Oct 4, 2010
I have a question. I have a class of Cars that I need to display in a simpli-ish string if they will be sold or not base on their number.
[Code]...
I'd like to display a simple string like this:Cars to be sold: 1, 3-5, 7-8, 11, which is based of the .Sell value.Is there some kind of heuristic to create this kind of string in .NET or is it just a bunch of for/each and if/then and redimming of arrays?
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Jun 9, 2011
I have decided I would start small and make a program that would create a "receipt" list in a listbox and a total. Now, I would like the user to be able to add their own "menu" items. I'm assuming the best way to go about this would be to have them actually add it to a database and then a function in the program will refresh the dataset with the new list. However, this is where my problem lies. How can I tell VB .net 2010 that I want to create a new button (or buttons) on the fly, in an orderly pattern on the form, based on the input from a DB?
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Mar 17, 2009
I would like to dynamically create an object (in my case a thread) and then be able reference that object. Simplistically put, I would like to read from a text file and then process each item using a thread (so that I don't have to wait for each item before starting the next). The problem is that I cannot think of a way to create a new thread dynamically ie. thread name so that I can then wait for all created threads before doing something else.
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Mar 28, 2009
Is there a way to dynamically create an object at runtime?Background: Basically i have an employee class that i want to instantiate every time an employee logs in. What i don't want it to have an employee object already created for every employee, but when they log in the object gets created.
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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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Dec 16, 2011
Im considering making my own command line interface with custom commands etc. I was thinking the following objects would be sufficient:
Textbox - for input
Rich text box - for showing processes and output
Button - to insert input
If it can be done, how can I provide line breaks in the output on the rich textbox e.g.
line1: input instruction
Line2: <cp><textfile.txt>
Line3: I/O error, file not found, check file root.
My version of CLI will have no integration with the windows CMD.
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