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 gridview displaying "registrationtype id" (FK) from the registration table. I want it to display the related name instead of the id from the registartiontype table.
View 1 RepliesI am using Entity Framework for my .NET application. I have been able to return objects and their directly-related objects as well (very convenient), but I am having trouble getting the objects of those objects.
IEnumerable<Lot> i = (((ObjectSet<Car>)_carRepository.GetQuery()) .Include(a => a.CarTypes).Take(10).ToList()
This works and I can access carTypes, however I cannot figure out how to access tables associated with CarTypes (e.g. tables which have fields associated with the car types). I tried to use a Join however I was unable to figure out how to get it to work right.
I use VS 2010 Ultimate. I created an 'asp.net web application' from scratch, added a 'ADO.NET Entity Model' to my project (EF4).
The problem I'm having is that whenever I try and use an EntityDataSource to pull data out of my entity model I am near constantly getting the following error:
"The metadata specified in the connection string could not be loaded. Consider rebuilding the web project to build assemblies that may contain metadata. The following error(s) occurred:"
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I have the following tables:
Campaigns (CampaignId, CampaignName, etc)
Urls(UrlId, CampaignId, UrlText)
I have a relationship setup between Campaigns table and Urls (FK_Url_Campaign) everything works fine when I try to add a new campaign but when I try to insert a new Url I get:
Entities in 'DatabaseEntity.Url' participate in the 'FK_Url_Campaign' relationship. 0 related 'Campaign' were found. 1 'Campaign' is expected.
This is my code:
// INSERT
public int Insert()
{
Url dbUrl = new Url();
dbUrl.CampaignId = (int)CampaignId;
dbUrl.Url1 = (string)Url;
context.AddToUrl(dbUrl);
context.SaveChanges();
return (int)dbUrl.UrlId;
}
Pretty much i want update/add new campaign and then I call Insert for Url. how would i go about doing this?
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.
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?
Adding data into kartlar table (RehberID,KampanyaID,BrimID) is ok. But which Kart'ID created? I need to learn which Id created after adding data (RehberID,KampanyaID,BrimID) into Kartlar?
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How can I do that? I want to get data from Kartlar which data I added?
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 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 am using the Entity Framework for the first time and want to know if the following is possible - I have generated my classes from the DB, and have one called Category.
Obviously it has all my fields in the table (ID, CategoryName, SortOrder etc..) but I want to know if I can add a custom property which is not in the table, but is actually the result of a custom method.
I want to add a new property called 'CategoryURL' which is basically the 'CategoryName' property run through a custom method and returns a hyphenated string.
My initial thought is inheriting from the generated Category class and creating something like this inside?
public string CategoryURL
{
get{ return MyCustomMethod(this.CategoryName) }
}
Is this the correct approach? And will 'this.CategoryName' work as I think it should? Basically the end result is when I return a list of 'Category' I want this to be part of the class so I can use it in my foreach loop.
i 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) file
and add new ADO.Net Data Servuce called "ADODataService" and add it as WebReferences called NorthwindService
so 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 category
so my code
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and my code
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so when i select category from Dropdownlist nothing happen :(
also you will find commented code in method BindCategory whuch is not work also.
I'm trying to have a View where the user can add items in a collection without having to go to a new View (the scenario is a sort of CV site where the user adds info about work experience, skills, etc, and it would seem absurd to go to a new View to add each little thing).
So I have an edit View that shows a number of text boxes for the already added items, and there's an ajax call to go to a method to fetch the collection fresh if the user adds an item.
Here are the methods in question:
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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
I've been at this same question in different forms now for a while (see e.g. Entity Framework and MVC 3: The relationship could not be changed because one or more of the foreign-key properties is non-nullable. ), and it's still bugging me, so I thought I'd put it a little more generically:
You have an entity object (using Entity Framework), say User. The User has some simple properties such as FirstName, LastName, etc. But it also has some object property lists, take the proverbial example Emails, to make this simple. Email is often designed as a list of objects so that you can add to that object properties like Address and Type (Home, Work, etc). I'm using this as an example to keep it generic, but it could be anything, the point is, you want the user to be able to add an arbitrary number of these items. You should also be able to delete items (old address, or whatever).
Now, in a normal web page you would expect to be able to add these items in the same View. But MVC as it seems designed only makes it easy to do this if you call up an entirely new View just to add the address. (In the template for an Index View you get the "Create New" link e.g.).
I've come across a couple of examples that do something close to what I mean here:
[URL]
and
[URL]
The problem is, although the sample projects on these sites work fine, with mock model objects, and simply lists (not an object with a child list), it's a different thing if you actually want to do something with the posted information - in my case save to database through the Entity Framework model. To adapt these cases to that, all of a sudden I'm in a maze of intricate and definitely not DRY code... Juggling objects with AutoMapper and whatnot, and the Entity Framework won't let you save and so on (see above link if you're interested in the details).
What I want to get at is, is it really possible that this is such an uncommon thing to want to do? Update a child collection in the same View as the parent object (such as the email addresses in this case)? It seems to me it can't be uncommon at all, and there must be a standard way of handling this sort of scenario, and I'm just missing it (and no one here so far has been able to point me to a straighforward solution, perhaps because I made it too abstract with my own application examples).
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 am using entity framework. My model has entity tblGameInfo where in navigation properties are associations called tblPlayer1 and tblPlayer2 which links to entity tblPlayer. I have listview on my page where I want to show game info with players names. I have found that in of listview I should have e.g. one of those:
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But it does not work. I got nothing displayed in a listview. I have tried many different options but cannot find working one. Probably is some simple mistake but I am new to asp.net and cannot find it. Second problem with this is editing. In edit template there is dropdownlist with all players.
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How do I databind it? It is not allowed to bind and change properties? It writes me that element does not exist on a list of elements.
I have been asking my self this question from the time i started workin in the software development field, What is the best way to access data? Which gives the best performance? Which is the best for maintainability? There are lots of solutions to deal with database in the Asp.Net web app,Entity framework 4.0 Classes generator using ADO.Net such as Code Author ( i liked the way it works and the way it accesses the database using the data access block in Microsoft Enterprise Library). i will start a new project tomorrow,and i don't know which approach is better?
View 2 RepliesI have the option to query and XML file or use the Entity Data framework. What datasource provider would have better performace?
View 2 RepliesI plan to use the ADO.NET Entity Framework for data access and have a few questions around this
1. Is there some inbuilt mechanism to handle concurrency (optimistic or pessimistic)?
2. Does the ADO.NET entity framework My SQL?
getting data from multiple Entities models into an MVC controller. Most of the examples I have seen for using EF in an MVC2 app only use a single entitiy.
I have just started using MVC2 in C# using the Entity Framework models (CIOps.model) created from an SQL database. I can create the controller and views using single tables of the model in MVC2, but I just cannot get my head around how to get data from multiple entity tables into the controller (similar to joins in T-SQL). I have included an example below of the controller code that works with a single entity table, tbl_tours (tbl_tour in DB).
Could someone please illustrate how this code would be changed to include additional columns from FK tables in addition to tbl_tours columns. E.g. the clients name from the tbl_clients, the coordinators name from the tbl_employees, and costs from tbl_costs entities? Is it possible to do this directly using the EF model entities/classes that are already created and not use LINQ, POCO, Repositories, etc.? The FK relationships are already in the EF models. I have included the whole controller code, but I just need a few examples of how to join the multiple entities, not rewrite every CRUD function function in the controller. I think this will get me over the hump in using EF in an MVC2 App. Also ignore the fact I am using the home controller, this will change in the application.
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