c# - Entity Framework update virtual property directly without creating new record -

here simple entity:

public class customer : entity {     public virtual location location { get; set; } } 

now suppose have customer already:

var customer = new customer() {location = new location("china")}; 

and want update location:

var customer = context.customers.first(x => x.location.country == "china"); customer.location = new location("america"); context.savechanges(); 

and when @ database, location record "china" has not been deleted: database has 2 location records association 1 customer record.

the reason issue i'm using virtual keyword on customer.location property, , when query customer entity database didn't use include method load location property, , did not use accesses lazy load it. ef can't track , know china location entity should deleted.

i think approach used update virtual property in line intuition. want update property, use update instruction "entity.xxx=...", add being forced use access of property or method call while loading "entity.xxx" not intuitive.

so looking better way replace entity's virtual property directly. suggestions?

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solutions update

i'm find 2 way easy,

first can use identifying relation(recommend).

another way can use objectcontext.deleteobject method, below example code:

public static class efcollectionhelper {     public static void updatecollection<t, tvalue>(this t target,  expression<func<t, ienumerable<tvalue>>> memberlamda, tvalue value)where t : entity     {         var memberselectorexpression = (memberexpression)memberlamda.body;         var property = (propertyinfo)memberselectorexpression.member;          var oldcollection = memberlamda.compile()(target);         oldcollection.clearup();          property.setvalue(target, value, null);     }      public static void clearup<t>(this ienumerable<t> collection)     {         //convert dbcontext iobjectcontextadapter         var objcontext = ((iobjectcontextadapter) program.dbcontext).objectcontext;         (int = 0; < collection.count(); i++)         {             objcontext.deleteobject(collection.elementat(i));         }     } } 

and can write code like:

customer.updatecollection(x => x.locations, null); 

not sure want, got.

the reason getting 2 locations because use new location("american"); add reference new location (ef don't know if china used customer, , never delete it, in type of query)

now if said.

customer.location.country = "america" 

the china overwritten america, working specific location's property.

read coments on question little extras

if want update location (new location("some new location")). this.

location oldlocation = customer.location; location newlocation = new location("america"); //check if new location country !exist if(!context.locations.any(a=> a.country == newlocation.country)) {     //if don't exist add (avoiding location duplicate)     customer.location = newlocation;     //if important delete old location     //(important after removed dependency,      //thats why after new location added)     context.locations.remove(oldlocation)     //finally save changes     context.savechanges(); }