I'm brand new to the Entity Framework and trying to learn all it can offer. I'm currently working my way through the MVC Music Store tutorial which includes the following code:
[code].....
I am using below code to get new inserted ID in auto identity column from database.
[code]....
It's working fine when I connect my application with MS Sql, but if I connect with Mysql, it always returns 0 (zero).
Is there any other way to get last inserted ID using Entity Framework?
I have to change the username column in my database to nullable, which means everywhere in my code, I now have to check username.HasValue and change references to username to username.Value. Is there anything I can do to avoid having to change all the references to username to username.Value?
View 1 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:
[Code]....
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.
[Code]....
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:
[Code]....
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
I have a weird thing happening. I have two identical databases installed on one virtual machine but under two different instances of SQLServer. For some reason, periodically when saving from one it will save to the other instead. Using debug, I have verified that the connection string is correct and when the item saves, it still saves to the wrong database.I use session variable, and am of the belief that it might have something to do with it...and t hat when I go from one to the other it is still getting the connection string form the other for some reason.To make sure that it isn't a problem, I make sure that I completely close out one database before opening the other in a new IE window.I assume that when I completely close out an internet explorer window that it abandons all session states. Is that true?
View 7 RepliesI'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 Repliessolve 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 Replies