.net - Entity Framework 4.1 Code First+MVC3 And Accessing Entities Of A Certain Type?

May 13, 2011

I am using Entity Framework 4.1 code first+MVC3 and the inheritence stratagy that I use is TPC

I have the following classes
Public Class ObjectBase
<Key()>
Public Property Id As Integer
Public Property Description As String
End Class

[Code]...

Question 1 (and question 2) should be very simple, but I have allready spent hours on Google to find an answer with no result at all. The only thing I have found is that you can get all computers in ObjectBase by writing context.ObjectBase.OfType(Of Computer), and that does not help since you cannot write context.BorrowObjects.ObjectBase.OfType(Of Computer) code samples in VB.NET (if you can), but more importantly: Please ensure that the codesamples you supply work without hours of modification!

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.NET Sample Entity Framework 4.2 Code First Entity Splitting?

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]....

Entity Framework Error - "Type Argument 'Namespace...EntityName' Does Not Satisfy The 'Class' Constraint For The Type 'TEntity'"

Feb 28, 2011

I have the following two tables defined...

CREATE TABLE [LogLevel] (
[Id] int primary key
,[Name] nvarchar(50) not null

[code]....

After creating a fresh endity model, I add the two tables above. When I try to build I get the following errors...

Type argument 'Inxsol.CommandPlan.Data.Model.Log.LogLevel' does not satisfy the 'Class' constraint for type parameter 'TEntity'.
Value of type 'System.Data.Objects.DataClasses.EntityReference(Of Inxsol.CommandPlan.Data.Model.LogLevel)' cannot be converted to 'System.Data.Objects.DataClasses.EntityReference(Of Inxsol.CommandPlan.Data.Model.Log.LogLevel)'.

[code]....

Entity Framework Insert In Code?

Mar 30, 2009

I have a simple Entity Framework. For simplicity's sake I will transform the entity names to Northwind Like.I have a IEnumerable Of Customer and Item Objects

C# - Are Microsoft Entity Framework And ADO.NET Entity Framework (.edmx) The Same

May 13, 2010

c# - Are Microsoft Entity Framework and ADO.NET Entity Framework (.edmx) the same?

In Entity Framework, We Can Use Model First, DB First, Code First But How Can We Create Table Programmatically?

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.

Manually Generate Primary Keys In Entity Framework 4.1 Code First?

May 7, 2011

What is the best way to manually generate Primary Keys in Entity Framework 4.1 Code First?

I am programming ASP.NET MVC 3 and I use a repository pattern.

I currently generate keys in a sequential order by using the [code]....

VB - Entity Framework 4.1: Describe Relationship Into The DbContext Definition Using A Fluent Code First Approach?

Dec 5, 2011

I have in my database a table (AccessControl) that describes a sort of users "access control list" for the informations contained in the table Customers and other tables.Example: the entity CUSTOMER is marked by the EntityId #1. If a user belongs to the department #6, he can access the records of customer #16 and #31, but he can't for #14, that can viewed by user in department #3:

[code]...

How can I describe this relationship into the DbContext definition using a fluent Code First approach?

.net - ADO.net Entity Framework - Update Only Certain Properties On A Detached Entity

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]....

Asp.net - Using ExecuteQuery() With Entity Framework, Entity Class

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.

Linq To Entities Filtering An Entity Dynamic/Strongly Typed?

Apr 24, 2009

I am binding a Winforms Grid to an entity. (For reasons I won't go into here it must be bound to the entity, not the result a query) The code is as follows:

grid.DataSource = myEntities.entityName.Where("it.field = " & field)

It works, but it obviously isn't strongly typed. Is there a way to define the Where clause of an entity using a strongly typed notation?

Update One Entity Based On Results Of Another LINQ-to-Entities Query

Apr 9, 2011

I have the following LINQ-to-Entities query:[code]This will give me all the resident assignments for the current year/term. Then I have this LINQ-to-Entities query:[code]This will give me all the rooms. I want to iterate through the assignments and based on what room is assigned update the occupancy in reset_occupancy. I'm not 100% sure how to accomplish this. Here is my pseudo code of what I want to accomplish:[code]

Update One Entity Based On Results Of Another LINQ-to-Entities Query?

Dec 15, 2009

I have the following LINQ-to-Entities query:

' Get all the residency assignments that match the term/year.
Dim assignments = From p In dbContext.Residents _
Where p.semester = term _

[code].....

.net - Working With The ObjectQuery Single Enumeration Challenge In Linq-To-Entities Entity SQL?

Dec 30, 2011

I'm working on modifying this example:

Using advWorksContext As New AdventureWorksEntities
' Call the constructor that takes a command string and ObjectContext.
Dim productQuery1 As New ObjectQuery(Of Product)("Product", advWorksContext)

[code]....

An ObjectQuery can be enumberated only once. (Subsequent attempts at enumeration throw an exception.) The enumberation takes place in the for each statement. The problem is that if the query is empty attempting a For Each will throw an exception. But if I check for a count:If productQuery1.Count > 0 Then . . .

That eats up my one chance at enumeration. I could nest the For Each in a try/catch block and throw away the empty query exceptions, but that's ugly.

LINQ To Entities Does Not Recognize The Method [Type] GetValue[Type]?

Mar 14, 2012

I've a simple class like this:

Public Class CalculationParameter{
public Long TariffId{get;set;}
}

In a workflow activity, I've an Assign like this:

(From tariffDetail In db.Context.TariffDetails
Where tariffDetial.TariffId = calculationParameter.TariffId).FirstOrDefault()

Dto is passed to Activity as an Input Argument.It raise following error and I'm wondering how to assign Id.LINQ to Entities does not recognize the method 'Int64

GetValue[Int64](System.Activities.LocationReference)' method, and this method cannot be translated into a store expression.

How can I assign the calculationParameter.TariffId to tariffDetial.TariffId?!

UPDATE:Screen shot attached shows that how I'm trying to assign calculationParameter.TariffId to tariffDetail.TariffId (car.Id = Dto.Id) and the query result should assign to CurrentTrafficDetail object.

Entity Framework - C# Or .Net?

Feb 18, 2010

My company is tossing around the idea of using the Entity Framework when it comes out with .NET 4. We are currently a VB.NET shop, but have some interest in switching to C#.Is there any major arguments for or against such a move?Does EF with C# hold any advantages in performance, coding ease, etc over VB.NET?

View 10 Replies

Add A Many-To-Many Relation In Entity Framework?

Apr 17, 2009

I am a newbie. I have been able to Add new entities where there is a One-To-Many Relation. I am having a problem (don't Know how to do it) adding a new Entity when the relation is using Many-To-Many. In my EDM I have:

[Code]....

ADO.NET Entity Framework Tools?

Apr 16, 2011

I downloaded the VB 2010 Express software, the total files that we included in the download was 15, but it only loaded up 12 of these files. The following downloads did not get loaded as follows:MS Visual Studio 2010 ADO.NET Entity Framework Tools

MS HelpViewe 1.0 x64

I tried reinstalling the downloads that did not using the VB Express 2010 setup, but they do no appear on the list of downloads, only the SP1 for MS SQL Server 2008 Express Server (x64).Do I require the downloads that did not load.

Asp.net Mvc - Entity Framework With Database?

Apr 21, 2012

Here are the entities that i have...

Public Class Account
Public Property AccountId As integer
Public Property AccountDescription As String
Public Property Transactions As List(Of Transaction)
End Class

[Code]...

i would like to make it suc that when i do "db.Account.find(1)" for example it also loads in the list of all transactions which have the coresponding AccountId. I'm not too sure what type of relationship this is?? anyway, right now i can do

Dim acct As Account = db.Account.Find(1) acct.Transactions = from ts in db.transactions select ts where ts.AccountId = acct.accountid but i know this is not the correct way, there must be a way to map this out so that entity can just load everything in one shot right?

Entity Data Framework 101

Sep 28, 2011

I am used to using datasets for my projects in terms of data access. I now set myself an easy app to work on in order to learn the entity data framework and how to retrieve & manipulate data.Can anyone guide me through on where to start, what are the advantages of this model, In what scenarios should I choose to use entity framework and what are the things (basis) I should now before starting.My datasets are working fine too. Are there any reasons for me not to stick with that way of accessing data? Or is this something to consider depending on the users of the website (for speed purposes etc.)

Entity Framework VB Join

Feb 28, 2012

I'm trying to learn EF in visual basic. I'm struggling with finding any easy to understand simple tutorial of how to do inner joins.

This is the SQL that i'm trying to replicate in EF:

SELECT Quote.LockedDateTime, IncommingQuoteStatus.StatusDesc, Users.FirstName
+ ' ' + Users.LastName AS UserName
FROM Quote

[Code].....

WPF With Entity Framework Or Linq?

Feb 8, 2011

I have some basic expirience in Visual Basic and programming Windows Forms programs. I know now that forms programs are no longer updated by Microsoft and that WPF is the way to go. No to mention the slicker interface you can create. I've also noticed that passing SQL strings to a database is no longer the standard either. It's either Entity Framwork or Linq.

So I am going for a fresh approach. I need to develop a program that will access a sql database and be accessed by about 10 concurrent users within the office. What's the best approach in general? Linq or Entity Framework? Also, could you recommend a book or two for someone who is new to WPF and Entity Framework? I do have some programming expirience, just none with WPF or the new ways of ADO.net 4.

.net - Entity Framework 4 Save And Cancel?

Nov 3, 2010

I'm currently testing the entity framework 4 for a simple app I wish to build.

how do you save and cancel changes on a record basis? Using the save changes method on the context persists all the changes to the database.

.net - Entity Framework Query With More Than One Join VB?

May 10, 2012

I'm trying to use the Entity Framework to create a complex query and get stuck in the joins. After browsing some of the documentations, I cannot seem to find the correct solution, so maybe someone here can help.

I have a data structure where a family has several family members, each of which can have more than one entry in the income table (on different registration dates) and can have more than one entry in the healthconditions table.

[Code]...

.Net Entity Framework - Let Keyword With A Condition

Jul 7, 2011

I need to make a if-else statement in the query meaning I only want to add the OpenAmount to ExpectedAmount if the type = Cash, the problem is that it only gives me the cash row not the other row.

[Code]...

Active Record With Entity Framework?

May 14, 2012

I'm working on a project that was built using ADO.NET (raw sql) and Active Record pattern. I am slowly moving it away from ADO.NET to Entity Framework Code First 4.3.Here is an example of the pattern. The interface is a static Load and an instance Save (and Delete -- not shown).

Public Class Part
Public Property Id as Integer
Public Shared Function Load(_id As Integer) As Part

[code].....

Asp.net - Accomplish With Entity Framework Without Using Two Contexts?

Apr 6, 2011

I have the following code:

Private Sub btnReserve_Click(ByVal sender As Object, ByVal e As System.EventArgs) Handles btnReserve.Click
Using dbContext As pbu_housingEntities = New pbu_housingEntities

[Code].....

executes it always get 0, because the row has not yet been created in the database. I can just move this last bit of code out into its own Context, but is there a better way to do this?

Asp.net Mvc - Editable Gridview With Entity Framework

Dec 20, 2011

I am trying to make an MVC index view with bulk editing functionality, but can't seem to get it working. I have replaced the Html.DisplayFor with HTML.editorfor items, and put the whole table in a form which submits back to my index function. I have tried various ideas, but currently my function is

[Code]...

Association End Is Not Mapped In ADO Entity Framework?

Jan 15, 2009

I am just starting out with ADO.net Entity Framework I have mapped two tables together and receive the following error:

Error 1 Error 11010: Association End 'OperatorAccess' is not mapped. E:Visual StudioprojectsBrandi IIBrandi IIHospitals.edmx 390 11 Brandi II

C# - Column Sequence And The Entity Framework?

Dec 28, 2009

So, when you bind a collection of Entity objects to a grid component, the grid displays those fields in the sequential order they are found in the SQL Table they came from. This shows that the ordinal position of the fields are associated with their corresponding entity properties... somehow or other.

So here is the question: How can I obtain the table field ordinal position by reflecting over an Entity Framework Entity's properties? Let me tell you what I know and what I have tried. Apparently, each data field property in an EF Entity is decorated with a System.Runtime.Serialization.DataMemberAttribute. This attribute appears to have an Order property. However, I have discovered that this property does not contain what I am looking for. The value for all Data Properties in an Entity seems to be -1. What ever order is, it isn't ordinal position.

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