The property Id is part of the object s key information and cannot be modified

Question

i m using Entity Framework 4 0 and having a silly problem that i can t figure out   I have two tables    Contact  Id  primary key   Value  ContactTypeId  foreign key to ContactType  ContactType  Id  Primary key   Type  Home  Cell  Work  etc     Entity Framework created the following two entities    Contact  Id  Value  ContactType  Navigation Property  ContactType  Id  Type  Contact  Navigation Property    I m using the following code to get the contact and update the contact type for that particular contact   Contact contact   dbContext Contacts Single c   gt  c Id    12345   contact ContactType Id   3    Throws the following exception    The property  Id  is part of the object s key information and cannot be modified    It looks so simple  I don t get it

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For me the issue was caused by the lack of a Primary Key to my table  after setting a PK for the table the problem was gone

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Just hoping this helps someone else  after struggling for hours with this because i knew i wasnt updating the PK and i definitely had a PK  I had the PK value databound to a menu bar to show the current PK value and this was causing the issue

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Another strange behavior in my case I have a table without any primary key EF itself creates composite primary key using all columns i e      lt Key gt           lt PropertyRef Name  ID    gt           lt PropertyRef Name  No    gt          lt PropertyRef Name  Code    gt      lt  Key gt    And whenever I do any update operation it throws this exception       The property  Code  is part of the object s key information and cannot   be modified    Solution  remove table from EF diagram and  go to your DB add primary key on table that is creating problem and re-add table to EF diagram it s all now it will have single key i e    lt Key gt           lt PropertyRef Name  ID    gt   lt  Key gt

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The entity that was created by the framework doesn t have a contact ContactTypeId property  It automatically removed it and created the ContactType association inside the Contact entity   The way to get it to work  as you suggested  is to create a ContactType object by querying the database and assigning it to contact ContactType  For example   Contact contact   dbContext Contacts Single c   gt  c Id    12345   ContactType contactType   dbContext ContactType Single c   gt  c Id    3   contact ContactType   contactType

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I am using EF 4 0 and WPF and I had similar problem  and      found the issue that solved it  at least for me  in a very simple way   Because  like you  I thought it must be simple to update a field in a table  i e  in your case  Contact  that is referenced to by a foreignkey from another table  i e  in your case  ContactType    However  the Error Message        is part of the object s key information and cannot be modified   only appears when you try to update a Primary Key  which wasn t my intention at all     Had a closer look at the XML code of my EntityModel and found it      lt EntityType Name  Contact  gt       lt Key gt           lt PropertyRef Name  ID    gt           lt PropertyRef Name  contactTypeID    gt     lt  -- This second line caused my problem -- gt       lt  Key gt       lt Property Name  ID  Type  int  Nullable  false    gt                   lt  EntityType gt    For some reason  maybe I made some foolish mistake within my database   when Visual Studio autogenerated for me the DataModel from my database  it added in that very table  Contact   where I wanted to update the field  ContactTypeID  a second PropertyRef  second line    I just deleted that second PropertyRef    lt PropertyRef Name  contactTypeID    gt    in both  the store model and the conceptual model  and      issue was solved  -    Hence  remains like    lt EntityType Name  Contact  gt       lt Key gt           lt PropertyRef Name  ID    gt       lt  Key gt       lt Property Name  ID  Type  int  Nullable  false    gt                   lt  EntityType gt    Updates and Inserts are now running smoothly like a baby       -   Hence  good idea to check the XML of the datamodel to verify that only your PK is listed as PropertyRef  Worked for me      -

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You should add   db Entry contact  State   EntityState Detached    After the  SaveChanges

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In my case  I want to duplicate the object  but change the id  so I use this  Common DataContext Detach object     Work like a charm

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I had this happening when I was editing related objects from two separate contexts at the same time  Example   DataContext ctxA   new DataContext    DataContext ctxB   new DataContext     Author orwell   new Author  Name    George Orwell     ctxA Add orwell   ctxB Add new Book  Name    1984   Author   orwell     ctxA SaveChanges    ctxB SaveChanges      My case was a little bit more convoluted  as this is obviously quite stupid  but in essence this was causing the error in my case

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In my case the error was appearing as I removed the KEY attribute of the ID field       Key  public long Id   get  set      So just putting the attribute back in it s place  made everything working again    Key   DatabaseGenerated DatabaseGeneratedOption Identity   public long Id   get  set

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There are two types of associations  Independant association where the related key would only surface as navigation property  Second one is foreign key association where the related key can be changed using foreign key and navigation property  So you can do the following     option 1 generic option  var contacttype   new ContactType Id   3   db ContactTypes Attach contacttype   customer ContactType   contacttype    option 2 foreign key option  contact ContactTypeId   3      generic option works with foreign key and independent association  contact ContactReference EntityKey   new EntityKey  container contactset   contacttypeid  3

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first Remove next add  for simple  public static IEnumerable UserIntakeFoodEdit FoodIntaked data                        DBContext db   new DBContext                var q   db User Food UserIntakeFood AsQueryable                var item   q Where f   gt  f PersonID    data PersonID                     Where f   gt  f DateOfIntake    data DateOfIntake                     Where f   gt  f MealTimeID    data MealTimeIDOld                     Where f   gt  f NDB No    data NDB No  FirstOrDefault                 item Amount    decimal data Amount              item WeightSeq   data WeightSeq ToString                item TotalAmount    decimal data TotalAmount                db User Food UserIntakeFood Remove item               db SaveChanges                 item MealTimeID   data MealTimeID   is key              db User Food UserIntakeFood Add item               db SaveChanges                 return  Edit

User · Answer

Try  contact ContactType   differentContactType    or  contact ContactTypeId   3    You are trying to set the Id of the ContactType  of the Contact  to 3

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This problem happens because you are referencing the same object more than once  This is not a limitation of EF  but rather a safety feature to ensure you are not inserting the same object with two different IDs   So to achieve what you are trying to do  is simply create a new object and add the newly created object to the database      This issue often happens inside loops   If you are using a while or foreach loop  make sure to have the New Created Object INSIDE the loop body   try this   Contact contact   dbContext Contacts Single c   gt  c contactTypeId    1234   contact contactTypeId   4  dbContext AddObject contact   dbContext SaveChanges

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in my case  i just set the primary key to table that was missing  re done the mappind edmx and it did work when you have the primary key tou would have only this   lt PropertyRef Name  id    gt    however if the primary key is not set  you would have    lt PropertyRef Name  id    gt   lt PropertyRef Name  col1    gt   lt PropertyRef Name  col2    gt    note that Juergen Fink answer is a work around

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In my case  I was creating an object declared and initialized together  I just initialized in the constructor or what you can initialize the object when required

[c#] The property 'Id' is part of the object's key information and cannot be modified

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