I'm working on a MVC3 application and I created my POCO classes from my database with the DbContext Code Generator. All goes fine until I got stuck in this situation. Note that I use the repository pattern and I use for every entity a dedicated repository whether get a new instance of the DbContext.
Now, I'm in this situation:
object A has a relation one-to-many with B (A can have one or many B)
object B has a relation many-to-one with C (C can have one or many B)
object B has a relation many-to-one with D (D can have one or many B)
I should add a new object B, consider that object C and D are yet existing, so I must only do the relation and the object A can be created or updated. In the specific consider that A is customer and B is subscriptions (C and D are virtual objects properties in B).
Now If I try to save I got duplicates in C and D tables, while the management of the object seems to work.
So, I thinked that I should detach the entities before do the relation, but when I call the SaveChanges() I got this error:
Store update, insert, or delete statement affected an unexpected number of rows (0). Entities may have been modified or deleted since entities were loaded. Refresh ObjectStateManager entries.
Here's the code:
Customer customer = customerRepository.Get(ID);
if (customer == null)
{
customer = new Customer();
customer.Email = Request.Form["Email"].ToString();
}
Subscription subscription = new Subscription();
subscription.Active = true;
subscription.DateSubscription = DateTime.Today;
Object C = objectCRepository.Get(Request.Form["IDObjectC"]);//Get C object from database
Object D = objectDRepository.Get(Request.Form["IDObjectD"]);//Get D object from database
if (C != null)
{
//I tried also to detach the objects before adding to subscription
subscription.C = C;
subscription.D = D;
customer.Subscriptions.Add(subscription);
if (customer.IDCustomer == 0)
customerRepository.Add(customer);
else
UpdateModel(customer);
customerRepository.Save();
}
And here the add and the save method of the customer repository:
public override void Add(Cliente cliente)
{
db.Cliente.Add(cliente);
}
public override void Save()
{
foreach (var entry in db.ChangeTracker.Entries()
.Where(e => e.State == EntityState.Modified || e.State == EntityState.Added || e.State == EntityState.Unchanged || e.State == EntityState.Detached))
{
string state = ObjectContext.GetObjectType(entry.Entity.GetType()).Name + " " + entry.State.ToString();
if (ObjectContext.GetObjectType(entry.Entity.GetType()).Name.Equals("C") || ObjectContext.GetObjectType(entry.Entity.GetType()).Name.Equals("D"))
{
entry.State = EntityState.Unchanged;
}
dbContext.SaveChanges();
}
I tried also to use this for objects C and D.
((System.Data.Entity.Infrastructure.IObjectContextAdapter)dbContext).ObjectContext.Refresh(System.Data.Objects.RefreshMode.StoreWins, entry);
And the error received is
The element at index 0 in the collection of objects to refresh has a null EntityKey property value or is not attached to this ObjectStateManager.
I noticed that in CTP5 was added the option AsNoTracking(), I tried to use it, but nothing!
I checked also the Concurrency mode for every properties involved in the operation and all are set to None.
I finished ideas :(!
Any help would appreciated! Thanks!
Actually I solved myself using on loading the AsNoTracking() method and before saving the entities I change the state to Unchanged.
//On loading
Context.Object.AsNoTracking().SingleOrDefault(l => l.Property == Property);
//On saving
Object.State = EntityState.Unchanged;
Object.SaveChanges();
Hope this helps someone.
Related
I'm using Entity Framework and I am trying to remove a NinjqEquiment from a list belonging to an instance of Ninja.When I retrieve the list of Ninjas,I make sure to include the equipment list, so I know they are there. Then I remove the equipment from the Ninja and try to save changes. I get the following error -
The entity type List`1 is not part of the model for the current
context.
using (var db = new NinjaDbContext())
{
//get ninjas with equipment included
var ninjas = GetAllNinjas();
//get ninja
var ninja = (from n in ninjas
where n.Id == id
select n).FirstOrDefault();
//get equipment
var eq = (from e in ninja.EquipmentOwned
where e.Id == removeEqId
select e).FirstOrDefault();
//remove eq from ninja
ninja.EquipmentOwned.Remove(eq);
//Make sure entity knows EquipmentOwned has been modified
db.Entry(ninja.EquipmentOwned).State = EntityState.Modified;
//save ninja
db.SaveChanges();
}
Just remove this:
//Make sure entity knows EquipmentOwned has been modified
db.Entry(ninja.EquipmentOwned).State = EntityState.Modified;
This causes the error.
EquipmentOwned is a List<Equipment>. It is not an Entry in EF terms so it is not tracked directly by it.
When you delete an entity from such collection, EF knows that there won't be any relationship between this particular ninja and this particular equipment. It won't delete equipment from database because other ninjas may use this equipment.
To delete it completely you should remove this equipment from corresponding DbSet<> like this:
using (var db = new NinjaContext())
{
//db.Equipment is a DbSet<Equipment>
//id is PrimaryKey of Equipment table
var eq = db.Equipment.Find(id);
db.Equipment.Remove(eq);
db.SaveChanges();
}
I have created an entity Appraiser and there are methods to select values, display data etc.
Now I want to save the changes made after data is displayed, I have a button named SAVE, which will be used to save changes.
I am not able to get how to save the changes of this Entity?
Entity name is Appraiser, and I have created methods like get AppriaserDetails etc in DAL, BL and used them in aspx.cs.
This is my code:
public void UpdateData(Appraiser appId)
{
var Appsave = context.Appraisers.FirstOrDefault(App => App.AppraiserId == appId.AppraiserId);
Appsave.AppraiserName = appId.AppraiserName;
Appsave.AppraiserPhones = appId.AppraiserPhones;
Appsave.AppraiserAppraiserCompanyId = appId.AppraiserAppraiserCompanyId;
Appsave.Address = appId.Address;
Appsave.City = appId.City;
Appsave.ProvinceState = appId.ProvinceState;
Appsave.Email = appId.Email;
context.SaveChanges();
}
If u want to insert new record, then can use
MyContext.Appraisers.AddObject(appraiserEntityObject);
MyContext.SaveChanges();
In case of update
if (appraiserEntityObject.EntityState == EntityState.Detached)
{
// In case of web, we got an existing record back from the browser. That object is not attached to the context yet.
MyContext.Appraisers.Attach(appraiserEntityObject);
MyContext.ObjectStateManager.ChangeObjectState(appraiserEntityObject, EntityState.Modified);
}
MyContext.SaveChanges();
Here MyContext is ur ObjectContext
OK, this thing just puzzles me.
I have a table, say Users, with columns UserID, Name, etc. Have an object mapped to it using CTP5. So now I want to test it, and do the following:
List<User> users = new List();
// Some init code here, making say 3 users.
using (UsersDbContext)
{
// insert users
}
So far so good, works fine.
Now I want to see if the records match, so I select the users back using the following code.
using (UsersDbContext dbc = UsersDbContext.GetDbContext())
{
List<Users> usersRead = dbc.Users.Where(x => x.ID >= users[0].ID && x.ID <= users[users.Count - 1].ID).ToList();
}
This throws and exception:
System.NotSupportedException: LINQ to
Entities does not recognize the method
'User get_Item(Int32)' method, and
this method cannot be translated into
a store expression.
EF has difficulties seeing that I'm just asking to return an int in Users[0].ID ?
If I replace a call to users[0].ID with a straight int - works fine.
I get what it's trying to do, but I thought it should be pretty easy to check if the method belongs to .NET or Sql Server ?
You are trying to access an indexer in an EF expression, which doesn't translate to an SQL query. You'll have to move the parameters outside the query like this:
int first = users[0].ID;
int last = users[users.Count - 1].ID;
List<Users> usersRead = dbc.Users.Where(x => x.ID >= first && x.ID <= last).ToList();
I have an ASP.NET Page that updates registered User Address Details for a selected record.
Below is the update method that I am calling from my controller.
When I am calling the ApplyPropertyChanges method, I am getting an error. Did anyone run into the same error while updating the record with Entity Framework?
Appreciate your responses.
Error message:
The existing object in the ObjectContext is in the Added state. Changes can only be applied when the existing object is in an unchanged or modified state.
My Update method:
[HttpPost]
public bool UpdateAddressDetail([Bind(Prefix = "RegUser")] AddressDetail regUserAddress, FormCollection formData)
{
regUserAddress.AD_Id = 3;
regUserAddress.LastUpdated = HttpContext.User.Identity.Name;
regUserAddress.UpdatedOn = DateTime.Now;
regUserAddress.AddressType = ((AddressDetail)Session["CurrentAddress"]).AddressType ?? "Primary";
regUserAddress.Phone = ((AddressDetail)Session["CurrentAddress"]).Phone;
regUserAddress.Country = ((AddressDetail)Session["CurrentAddress"]).AddressType ?? "USA";
miEntity.ApplyPropertyChanges(regUserAddress.EntityKey.EntitySetName, regUserAddress);
miEntity.SaveChanges();
return true;
}
The error is the object is detached from the context, and ApplyPropertyChanges thinks the object is added because it isn't attached. So you would need to query from the data context or get an attached form and then apply the changes then.
HTH.
What Dave Said
+
You need to Attach() the disconnected entity to your object context:
http://msdn.microsoft.com/en-us/library/system.data.objects.objectcontext.attach.aspx
miEntity.Attach(regUserAddress);
miEntity.SaveChanges();
Just add the following code before miEntity.SaveChanges():
miEntity.Entry(regUserAddress).State = EntityState.Modified;
First select the record (object entity), search by key through the ObjectContext. For example if the search ArticleSet EntitySet called for there to record, and once you get it modified its properties with new values and then call SaveChanges() of ObjectContext.
Example:
ObjectQuery<Article> myArt=Context.ArticleSet.Where myArt = (row => row.ArticleId == value);
myArt.Description=" new value ";
etc. ..
etc ...
Context.SaveChanges ();
I'm trying to bind an ASP.net DropDownList to the results of an entity framework query, while still maintaining multi-tier separation. (i.e. I don't want my UI code to contain query details, nor my Data Layer code to have UI dependencies.) My code-behind in the Page_Load event handler looks like this:
IEnumerable<Lookup> TypesLookup = Business.DocumentBO.GetDocumentTypes(_LookupTypeID);
DocTypeDropDownList.DataSource = TypesLookup;
DocTypeDropDownList.DataTextField = "Description";
DocTypeDropDownList.DataValueField = "LookupID";
DocTypeDropDownList.DataBind();
While my data code looks like this (there's an intermediate business layer as well, but there no processing there as yet -- just a pass-through.):
public static IEnumerable<Lookup> GetLookups(int LookupTypeID)
{
using (VLFDocumentEntities context = new VLFDocumentEntities())
{
IEnumerable<Lookup> l = (from c in context.Lookup
where c.LookupTypeID == LookupTypeID
select c);
return l;
}
}
When I get to the DocTypeDropDownList.DataBind();, it throws an ObjectDisposedException with the message "DocTypeDropDownList.DataBind();". Can anyone advise me on the best way to tackle this?
Thanks,
Andy
Don't you have to detach the objects from the context? E.g:
IEnumerable<Lookup> l = (from c in context.Lookup
where c.LookupTypeID == LookupTypeID
select c);
foreach (Lookup lookup in l)
context.Detach(lookup);
return l;
Why don't you just use a List<>?
public static List<Lookup> GetLookups(int LookupTypeID)
{
using (VLFDocumentEntities context = new VLFDocumentEntities())
{
return (from c in context.Lookup
where c.LookupTypeID == LookupTypeID
select c).ToList();
}
}