Updating a Virtual list of objects in C# to Microsoft Sql Server

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Alright, so the problem I'm having is trying to update a virtual list of objects within a model to Microsoft Sql Server.

My Class looks like this

C#

public class CustomObject
{
    public int Id { get; set; }
    public string origin { get; set; }
    public Type Type { get; set; }
    public virtual List<CustomObject> CustomObjects { get; set; }
}

and when I try something like

C#

dbContext.CustomObjects.Add(customObjects);

it works fine, but when I try something like

C#

var customObject = dbContext.CustomObjects.Find(Id);
customObject = newObject;
dbContext.Entry(customObject).State = System.Data.EntityState.Modified;
dbContext.SaveChanges();

it seems to update the information like the origin but not the CustomObjects variable in Microsoft Sql.

Posted 1-Jul-15 8:33am

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Mark Miller · Answer 1 · 2015-07-01T10:27:00

First, I assume CustomObjects is declared as a DbSet<customobject></customobject> in your DbContext class.

Here you are pulling a record from the SQL table:

C#

var customObject = dbContext.CustomObjects.Find(Id);

Here it appears you then replacing the object you just pulled from the DB with one you (I'm assuming) created within your application:

C#

customObject = newObject;

Finally you attempt to set the object's state to modified and save it, which doesn't work:

C#

dbContext.Entry(customObject).State = System.Data.EntityState.Modified;
dbContext.SaveChanges();

I think your problem lies in the customObject = newObject; line because you are completely replacing the object you just pulled with a new object, including the primary key.

Try updating individual properties of the object instead of overwriting the object in it's entirety.

I think your example code is closer to the following:

C#

var customObject = dbContext.CustomObjects.Find(Id);
dbContext.CustomObjects.Remove(customObject);
dbContext.SaveChanges();
dbContext.CustomObjects.Add(newObject);
dbContext.SaveChanges();