I need to add a custom property to an Entity Framework class, however when I do I get the "The property name XXX specified for type XXX is not valid." error. Is there some attribute I can give the property so it is ignored and not mapped to anything?
Edit: If I add a custom property, as per Martin's example below, then the following code will raise the above error at the SaveChanges call.
MyEntities svc = new MyEntities(url);
MyEntity ent = new MyEntity();
ent.MyField = "Hello, world";
svc.AddMyEntity(ent);
svc.SaveChanges();
You can add a property in code:
public partial class MyEntity {
public String MyCustomProperty {
get;
set;
}
}
The Entity Framework generate partial classes enabling you to customize the generated class.
Also, to comment on your code I think should change it to something like this:
MyEntities svc = new MyEntities(url);
// Create MyEntity using the factory method.
MyEntity ent = MyEntities.CreateMyEntity(...);
ent.MyField = "Hello, world";
svc.AddMyEntity(ent);
svc.SaveChanges();
This will ensure that your entity is properly initialized.
Here is the answer:
http://social.msdn.microsoft.com/Forums/en-US/adodotnetdataservices/thread/b7a9e01d-c5c2-4478-8f01-00f7f6e0f75f
Edit:
A better link describes the final compact answer of Adding an Attribute to prevent serialization of the Entity when sending to the Service.
Related
I am working on an asp.net mvc core 2.0 project and entityframework.
I am working with viewmodel concept.
This mean i do not pass entities instances directly to my view, i pass a viewmodel instance which only contains what the view needs.
in one case, i need to pass the entire entity fields plus other informations.
What i've done is a derivated my ViewModel class from my Entity Class. and i add the extra fields:
public MyViewModel: Person
{
// I will automaticly have Person fields in MyViewModel
public bool IsSelected {get;set;}
public String otherinformation {get;set;}
...
}
I am fed up with assigning each fields of my viewmodel from my entity instance.
myviewmodelinstance.field1 = myentity.field1;
myviewmodelinstance.field2 = myentity.field2;
myviewmodelinstance.field3 = myentity.field3;
myviewmodelinstance.IsSelected = false;
...
And i need to do the inverse operation in the postback.
Is there a way to "copy" or "clone" every fields, like this:
myentity.CopyTo(myviewmodelinstance);
myviewmodelinstance.IsSelected = false;
Thanks
You could use the AutoMapper to achieve it. It is the ideal way to perform it. Another option is that you can serialize and deseriliaze the object as json.
var myviewmodelinstance = JsonConvert.DeserializeObject<MyViewModel>(JsonConvert.SerializeObject(myentity));
Note : The code I provided required Json.Net
Is it possible to add summary properties(no database column) according LINQ from another property(column) in EF generated class from database and this property don't update(delete or remove from class) when update model from database(because this property(cloumn) is not on database)
Yes, it is. Classed generated by Entity Framework as an Entitied are always marked partial. It lets you extend the functionality with your own properties or method.
Let say your entity class is named Post. You can extend it with code like that:
public partial class Post
{
public int Average
{
get
{
return this.Items.Average();
}
}
}
Because it's not a part of designer-generated file it won't be overwritten when it's regenerated. However, there is one requirement to make it work: your custom part of Post class has to be in exactly the same namespace as code generated by EF.
Try using the [NotMapped] attribute on a property in a partial class. This will be ignored by Entity Framework.
public partial class EntityName
{
[NotMapped]
public int CalculatedProperty
{
get
{
return Numbers.Sum();
}
}
}
As far as I am aware, for the property to be saved in the database it cannot be ReadOnly.
IIdentity properties: AuthenticationType, IsAuthenticated and Name are all ReadOnly.
Is making the wrapper to the properties that need to be saved the only solution or there are better ones?
EDIT:
I might not have explained my question that well. Here is the sample code for one of the ReadOnly properties, I have added UserName property for the Entity Framework:
Public Property UserName As String
Get
Return _userName
End Get
Private Set(value As String)
userName = value
End Set
Public ReadOnly Property Name As String Implements System.Security.Principal.IIdentity.Name
Get
Return UserName
End Get
End Property
What I wanted to ask is if there is any better way of doing it.
IIdentity properties are read only but the implementation can have setters. If you are using EDMX for mapping you don't have to expose these setters as public.
Edit:
This is possible in C# so hopefully you can use similar approach with VB.NET (I can only read VB code, not write):
public interface ITest {
string Name { get; }
}
public class Test : ITest {
public string Name { get; set; }
}
The class offers setter even the interface didn't define it.
The EF persists objects, not interfaces. Your object can have whatever properties you would like it to have. You cannot add an interface to your entity model, but you can add an object type which implements that interface.
I have a stored procedure in my Entity Framework Model. I've added a Function Import and mapped the results to a Complex Type.
I want to add an extra property to this Complex type, that I'll populate in my Domain Service, not coming back from the stored procedure. I added a myClass.shared.cs file and implemented added the property like so:
//myClass.shared.cs
public partial class myClass
{
public string myProperty {get;set;}
}
I populate this in my domain service when I return the object, e.g.:
public myClass GetMyClass(int myClassID)
{
myClass theClass= this.ObjectContext.StoredProc(myClassID).FirstOrDefault();
class.myProperty = 12345;
return theClass;
}
When I get the return values of this method on the client side theClass.myProperty is always null but all values from the stored procedure are populated, am I missing something?
I've tried decorating the myProperty with the [DataMember] attribute but this throws the error:
"The type 'myClass' already contains a
definition for 'myProperty'"
How can I get this to return the value set in the Domain Service to the client?
There was no need to put this in the shared.cs class. The shared.cs class copies the actual code over to the client side and is useful for adding methods etc. but to add a new property, all I had to do was add a partial class (NOT in myClass.shared.cs) and decorate it with DataMember.
public partial class myClass
{
[DataMember]
public string myProperty {get;set;}
}
I'm using VS2010, EF4 feature CTP (latest release), and POCO objects, such as the example below:
class Person
{
public int ID { get; set; }
public string Name { get; set; }
public virtual IList<Account> Accounts { get; set; }
...
}
class Account
{
public string Number { get; set; }
public int ID { get; set; }
...
}
For the sake of brevity, assume context below is the context object for EF4. I have a dbml mapping between entity types and the database, and I use it like this with no problem:
Person doug = context.Persons.CreateObject();
doug.Name = "Doug";
context.Add(doug);
context.Save();
doug.Accounts.Add(new Account() { Name = "foo" });
context.Save(); // two calls needed, yuck
At this point, the database has a Person record with the name "Doug", and an account record "foo". I can query and get those record back just fine. But if I instead try to add the account before I save the Person, the Accounts list is null (the proxy hasn't created an instance on that property yet). See the next example:
Person doug = context.Persons.CreateObject();
doug.Name = "Doug";
doug.Accounts.Add(new Account() { Name = "foo" }); // throws null reference exception
context.Add(doug);
context.Save();
Has anybody else encountered this? Even better, has anyone found a good solution?
Person doug = context.Persons.CreateObject();
doug.Name = "Doug";
context.Add(doug);
doug.Accounts.Add(new Account() { Name = "foo" });
context.Save();
This will work
Yes and yes!
When you new the POCO up (as opposed to CreateObject from the Context), no proxies are provided for you. This may seem obvious, but I had to explicitly remind myself of this behavior when chasing a similar issue down. (I know this isn't the situation you described in the question, but the overall issue should be acknowledged).
Initializing collections in the constructor of the POCO does not interfere with proper EF4 proxy lazy-loading behavior, from what I've observed in my own testing.
OK, all this being said, I now see your comment to the previous answer -- why don't I have a proxied Addresses collection when I request a new Person from my context? Do you have lazy loading enabled on the context? Seeing how we're dealing with navigation properties, I could see where having lazy loading turned off may make a difference in this situation.
ISTM that if you expect the framework to do all this for you then you wouldn't really have a "POCO", would you? Take your Person class, with the code above. What would you expect the state of the Accounts property to be after construction, with no constructor, if the EF weren't involved? Seems to me that the CLR will guarantee them to be null.
Yes, proxies can initialize this when necessary for materialization of DB values, but in the EF, "POCO" actually means "Plain". Not "something packed with runtime-generated code which we pretend is 'Plain'".