Entity Framework 4 Merge Changes Between Two Entities?
Feb 8, 2011
I use the ObjectDataSource in an ASP.NET Application.
Using the ASPxGridView. When Updating it goes back to the Data Access Layer and tries to update the Entity, now as I can see while having some properites (Columns, Visible = false) when the entity arrives in the update method the visible = false columns have no values.
I don't want to show all the columns...what if I need 3 of the 30 columns? So I thought I would get the original entity from the context and merge the differences from the updated entity.
View 1 Replies
Similar Messages:
Mar 12, 2010
I have a Consumer class and a BillableConsumer : Consumer class. When trying to do any operation on my "Consumers" set, I get the error message "Object mapping could not be found for Type with identity Models.BillableConsumer.
From the CSDL:
[code]....
Is this because I did not specifically add the BillableConsumer entity to the object set? How do I do that in a POCO scenario?
View 1 Replies
Oct 19, 2010
Due to the way the database was designed, in my model I have a User entity. The Contact entity inherits from the user entity, and the Profile entity inherits from the Contact entity.
How can I get a list of Profiles, and, how do I create a Profile?
View 1 Replies
Aug 13, 2010
let us assume that I have a reusable business layer that further makes use of a data access layer that was implemented using Entity Framework 4.0. The entities returned/consumed by the business layer are self-tracking, allowing us all the goodies that come with those type of entities. I would like to be able to store the entities I work with across post backs (on order to avoid re-querying every time). Basically let us assume I have a paged GridView with 10 items in it, and something like a DetailsView to edit those items. Every time you select a new row on the grid, the details view updates with the information of the selected row. My preference would be to only query for the entities on the initial request of the page and store it in session. Then subsequently I have a list of entities that I can work with and eventually modify and send back to the business layer with all of the changes.
I really want to use session instead of view state to reduce the page payload (self tracking entities are heavy) however I really like view state for this because of the fact that when the user navigates away from the page there is no residual effect. Some of the things that worry me are: When a user navigates away from the page to another page, the entities from the previous page are still in session. I could always do something on load of a page to do housekeeping type of work. Not sure if that's good practice. I am worried about people opening browser tabs and having two views into the same page, it seems like that might pose a problem. Is this even a good approach? Seems like I am trying to have the best of all worlds, it would definitely be much easier to simply re-query on every post back for the entities and pay the 50-100ms hit of the database trip.
View 2 Replies
Dec 14, 2010
I have a model that consists of Order, OrderLine, Product.
I want to create an Order and add OrderLines (each OrderLine related to a Product). I create the Order and add new OrderLines to it. Between posts I store the Order entity in Session (or ViewState). Just so you know I have added suppport for binary serialisation which works fine.
The relationship is therefore Order > OrderLine(s) > Product(s).
You might have already guessed what the problem is - that when I SaveChanges() I get the usual 'AcceptChanges cannot continue because the object's key values conflict with another object in the ObjectStateManager.' error.
I have referred to a number of articles online but none seem to handle this case (where I have the relationship across more than two entities) e.g. [URL].
This must be a very common requirement surely? Is there anyone out there doing the same kind of thing with Entity Framework (and without using DTOs etc)?
View 2 Replies
Mar 3, 2010
I am trying to get some guidance with this issue:
I have a Customer object that has two address ID fields (one for HomeAddress and one for WorkAddress)
I am loading the Address Objects by using Include="HomeAddress, WorkAddress" and then binding to the properties using the Navigation Property on the Customer Entity
Can I use just one FormView for doing the Insert/Updates and binding it to an EntityDataSource or would I have to do all the Inserting/Updating manually?
View 1 Replies
Feb 4, 2010
Using a very run-of-the-mill database, with identity int for primary keys, a Dynamic Data Entities Project (EntityFramework) displays the primary key for view and edit. When using Linq to Sql, the primary key fields are not displayed.
I would like to hide the primary keys and use Entity Framework (VS 2008, .Net 3.5 sp1).
View 1 Replies
Mar 15, 2011
I created two stored procedures in SQL Server Management Studio.
First procedure add field in ProjcetsToUsers table (for many-to-many associations)
[code]....
I can delete the user from the project and then add another, and the new one is added but removed the remains.
As for data base both this function work correctly.
View 1 Replies
Oct 10, 2010
DbClick the code behind file of NerdDiner.edmx,It reads "This code was generated from a template." on the top comment lines. I generate my own .edmx file automatically with VS2010, just found that the .designer.cs file didnt contains Objectset,Methods as nerddinner does IDK which template hanselman used to generate this .edmx files，dont tell me he wrote it all by himself! Shoud .edmx and its code behind file be generated automaticlly without hard-coding?
View 4 Replies
Oct 25, 2010
Is 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.
View 1 Replies
Nov 2, 2010
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 Replies
Jun 30, 2010
I 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?
View 1 Replies
Feb 9, 2011
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>();
}................................
View 9 Replies
Feb 10, 2011
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.
View 2 Replies
Aug 5, 2010
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
[Code]....
View 1 Replies
Mar 31, 2011
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.
View 1 Replies
Sep 21, 2010
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 Replies
Jan 5, 2011
I 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;
View 2 Replies
Feb 3, 2011
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.
View 4 Replies
Sep 24, 2010
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
View 2 Replies
May 22, 2010
And not doing a View that connect two tables ?Is there a way to connect two entities together in one new entity?
View 1 Replies
Oct 11, 2010
I am currently trialing EF4 code-first. My POCO classes inherit from an Audit class that contains CreatedBy, CreatedOn, UpdatedBy, UpdatedOn. I was hoping the framework would include the Audit properties in my Action table when creating my database, however this doesn't appear to be the case. Does anyone know how to enable this without overriding the OnModelCreating() method?
Public Class Audit
Public Property CreatedOn as DateTime
End Class
Public Class Action
inherits Audit
Public Property ActionId As Int32
End Class
View 1 Replies
Jul 29, 2010
i have a table with a field name called 'Firstname' and another field name called 'Lastname'. I would want to have a single column in my GridView which show Fullname and then the firstname and lastname are showed here under an alias. Also, i am binding my GridView using LINQ.So is there a way to create aliaswith LINQ and to use these with GridView ? Would love to have an hint about how i can realize this task.
View 5 Replies
Jul 29, 2010
I just want to know what are the main differences between ADO.NET Entities Framework and LINK to SQL ? It is okay to use ADO.NET EF for a simple website ? What advantages each have?
View 3 Replies
Mar 6, 2011
can we say like "Entity frame work make use of linq to entities"?
what is the relation between linq qnd entity frame work?
View 2 Replies
