I'm using VS 2008 with SP1. I want to use SP in the entity framework. The SP uses join of more than 1 table to return data. Most of the online examples I show, use the single table. How to return data of more than one tables?
View 4 RepliesIs there a way to export a EF 4.0 Data Model to EF 3.5?
I looked around and found that we are not able to access EF 4.0 from a ASP.Net 3.5 project here: [URL]
Our project is the 1st to go to .Net 4.0 using Entity Framework and we (the team) were wondering if there was a way for the other projects that "might" need to access our data that are still using the .Net 3.5 framework.
I am new to entity framework , it is really very good , but I want to know what is the difference between using entity framework with stored procedure or without stored procedure , which one the faster and what is the benefits for using stored procedures with entity framework.
View 1 RepliesI have an EDM, it includes the entities extension and history. My goal is to use history to keep track of all the changes made to extension entity. For example, if extension with ID 223 has its property 'Name_Display' changed - I want the history entity to record this.
I'm using ASP.NET with VB.NET. Where in my code do I put the hook to say, "update the history entity" and what should that hook look like?
I get an cast exception when i am trying to insert an entity in Entity Framework (using code-first). From this code :
public virtual T Insert(T entity)
{
return Context.Set<T>().Add(entity);
}
The cast exception is like "impossible to cast ...Collection'1(Entity) to type (Entity)" I can't figure out why. I am pretty sure ive done everything right. Post entity
public class Post
{
public long PostId { get; private set; }
public DateTime date { get; set; }
[Required]
public string Subject { get; set; }
public User User { get; set; }
public Category Category { get; set; }
[Required]
public string Body { get; set; }
public virtual ICollection<Tag> Tags { get; private set; }
public Post()
{
Category = new Category();
if (Tags == null)
Tags = new Collection<Tag>();
}................................
I am mapping a stored procedure to an entity by right clicking on the entity (in the .edmx) and selecting "Stored Procedure Mapping." This brings you to a Mapping Details - "Name of Entity" Window that allows you to select the insert, update, and delete stored procedures associated with the Entity. It also maps the stored procedure parameter to the Entity "Property" (Column).
I'm gettin an error "error 2042: Parameter Mapping specified is not valid." The cause of the error is fairly obvious, in the Insert stored procedure that has been selected, a 'CHAR' parameter is being mapped to an Int32 Entity Property. I altered the stored procedure parameter to match the entity, I deleted the stored procedure, readded, and reslected it as the Insert function. I also cleaned, validated, updated model from database. No matter what I do, the parameter list in the mapping details doesn't reflect the change to the stored procedure. It's stuck on a char --> int32 mapping, even though it has been changed, like it's buried deep in meta data some where.
I am trying to add a new entity and have to refernce associated data to add it. I cannot load the Referencetables. Giving "The EntityReference could not be loaded because it is not attached to an ObjectContext." How do i complete this task in Entity Framework 3.5
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I have a stupid problem with the Entity Framework. I get the following Exception:
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I have an entity with a 4 fields representing the primary key. I copy it via serialization (works fine). I set the old entity to not valid (Datefield set to a date in the past, this field is part of the PK) and set the copied entity to DateTime.Now.Date. When I call context.AddObject I get the Exception above. I tried copying the entity via reflection but the entity has 3-4 references. And when copied, I get another Exception before even Adding the entity to the context. I also tried setting newObj.EntityKey = null and reset all the fields neccessary for the PK. I just want a whole copy of an entity with a different primary key (and some other fields changed too) and Create it in the database.
I'm writing a custom .NET MembershipProvider (not the built in one) and trying to update using Entity Framework. But of course i have no access to (Try)UpdateModel. How can i update it?
View 3 RepliesI have an Events table and an InstallmentPlans table. The relationship is 0..1 : an Event can have 0 or 1 Installment plans. If I want to remove the existing InstallmentPlan for an event, how do I do this? Setting it to null doesn't seem to work:
_event.InstallmentPlan = null;
Here's a simple code snippet where I create a new Entity object and call SaveChanges() to create a new record in the mapped database table.
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What I'm trying to figure out is whether there is a way to derive this new key for my entity, e, from the ObjectContext, m? The reason for this is that the way my actual code is structured, my entity object is already out of scope at the point where I call the SaveChanges() method.
I am trying to do something like this:
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But ofcourse it is not working as I want to. The Ordering works on Question.Order, but I would also the
Questions.SubQuestions List to be ordered according to SubQuestions.Order
solve this problemi create example using Northwind database so i create a new website and add new ADO.Net Entity Data Model (.edmx) called Northwind.edmx and i add Categories and Products table inside this (.edmx) fileand add new ADO.Net Data Servuce called "ADODataService" and add it as WebReferences called NorthwindServiceso i add new web page and drag DropdownList and Gridview as i want to bind Dropdownlist to all categories and when i select category from Dropdownlist bind Gridview to all Products related to this categoryso my code
[Code]....
and my code
[Code]....
so when i select category from Dropdownlist nothing happen :(also you will find commented code in method BindCategory whuch is not work also :(
i have been using entity framework in win app. but i notice i cant use it in web app. is there a different way to do it in web
View 1 RepliesI've been trying to learn about the entity framework. I plan on using it in a rewrite of a site I'm doing.But everything I can find on it is on the 3.5 framework and they all mention that there will be changes in 4.0. Does anyone know of a good article, video series, and or tutorial on the entity framework in 4.0?I've worked a lot with Linq to Sql, so I don't think I'll have too much trouble working with the entity framework, but I'd like to learn more about the current version.
View 3 RepliesI have 3 tables in the database, with a Many to Many relationship:
Assessment(assessID, userID, A, B, C)Grade(gradeID, scoreA, scoreB, scoreC)AssessmentGrade(assessID, gradeID) [PK and FK]I can already Insert into the Assessment AND Grade tables without any problems.I cannot seem to figure out how to Insert into the AssessmentGrade table. There is no separate Entity, because there is only the PK/FK in the AssessmentGrade. I have looked at some tutorials, but none of them seem to address my situation.
I m making an application in asp.net 3.5. I have added .edmx file in my appliaction and create all the instances of datatable in the edmx file. now i want to know how to start querying with this edm like inserting updating and selecting etc. from database.
View 7 RepliesWhats the best method to use with MVC? Entity Framework or LINQ to SQL?
View 4 RepliesIm working on a greenfield project and have to make a decision on the technology we'll use for the data access layer. Ive used LINQ to SQL for a few years and am happy and comfortable with this, but now with entity framework available this is another method to consider. Are there any pitfalls using entity framework as opposed to LINQ to SQL ? Ive read that there are performance issues with entity framework, is this true? Id really like to get an overall feel for using one method over the other, anyone have any thoughts/comments/recomendations?
View 1 RepliesI'm trying to learn MVC. Now I wonder whats the different between entity framework and LINQ TO SQL? Wich is the best to use and why?
View 19 RepliesIm new to development for the windows server platform. Can someone tell me the difference between Linq to SQL and EF4?
View 2 Repliesi'm using the entity data model to insert data to my database. the thing is that when inserting data to more than one table i want to ensure that all actions completed correctly(or catch an exeption if not).
View 1 RepliesI have Windows 7 professional 64 bit with VS2008, .Net 3.5 SP.1
I am unable to install Entity Framework and getting the message Incorrect Product Configuration
Where can I download entity framework for Windows 7 64 bit?
I have been updating my Entity Framework by simply right clicking and clicking on "update model from database". I usually go under the "Add" tab and then click the tables and click finish. I also use "refresh" sometimes as well. What are the differences between these? and also when I do refresh or add sometimes the entity comes out wrong or keeps some of the old information in cache, how can I just get the entity to match my database and clean out any of the old cached things.
View 3 RepliesI am working on a project that converts our enterprises code library so it uses the entity framework.
We use a ControllerFactory that "generates" controllers. These controllers contain the business logic of our enterprise. To avoid the problem of context conflicts (An object of one context that needs to be added to a new context, bla bla bla), we create a new Entity Context for each ControllerFactory we instantiate. All the controllers that are generated from the ControllerFactory use the same Entity Context for fetching and saving data.
Now, we have added a constructor to the ControllerFactory to make it Read-Only (Context.SaveChanges can't be executed) so it is a little bit safer and it doesn't save things we don't want to save when loading data to show to the user.
Then I started thinking about performance. Since the Context is never saved in a Read-Only factory, I have already disabled the state tracking of some Entities to speed things up.
But I wondered if we could improve the speed even more.
Since locking is not nescessary for only fetching entities, I would like the Entity Framework to add the WITH (NO LOCK) element to the SQL SELECTs it creates. But I Have found out that this only works when using transactions, and I can not use one transaction for the whole ControllerFactory.