Entity Framework Code Only error: the model backing the context has changed since the database was created

by

I found the answer in the comments on this post on Scott Guthrie’s blog.

http://weblogs.asp.net/scottgu/archive/2010/08/03/using-ef-code-first-with-an-existing-database.aspx

For those who are seeing this exception:

“The model backing the ‘Production’ context has changed since the database was created. Either manually delete/update the database, or call Database.SetInitializer with an IDatabaseInitializer instance.”

Here is what is going on and what to do about it:

When a model is first created, we run a DatabaseInitializer to do things like create the database if it’s not there or add seed data. The default DatabaseInitializer tries to compare the database schema needed to use the model with a hash of the schema stored in an EdmMetadata table that is created with a database (when Code First is the one creating the database). Existing databases won’t have the EdmMetadata table and so won’t have the hash…and the implementation today will throw if that table is missing. We’ll work on changing this behavior before we ship the fial version since it is the default. Until then, existing databases do not generally need any database initializer so it can be turned off for your context type by calling:

Database.SetInitializer<Production>(null);

More Related Contents:

  1. Entity Framework/Linq EXpression converting from string to int
  2. Internal .NET Framework Data Provider error 1025
  3. Entity Framework 4: How to find the primary key?
  4. Change db table name in EF4 (entity framework 4)
  5. Entity Framework Multiple Object Contexts
  6. Repository Pattern, POCO, and Business Entities
  7. VB Net Class in C# [closed]
  8. How do I apply OrderBy on an IQueryable using a string column name within a generic extension method?
  9. Entity Framework 4 – AddObject vs Attach
  10. The cast to value type ‘Int32’ failed because the materialized value is null
  11. EF Including Other Entities (Generic Repository pattern)
  12. Filter/Search using Multiple Fields – ASP.NET MVC
  13. Why would try/finally rather than a “using” statement help avoid a race condition?
  14. Retrieve an object from entityframework without ONE field
  15. Finding the reason for DBUpdateException
  16. DbContext discard changes without disposing
  17. EF4 Code First: how to add a relationship without adding a navigation property
  18. .Include() vs .Load() performance in EntityFramework
  19. Max return value if empty query
  20. Group by with multiple columns using lambda
  21. How to do an “in” query in entity framework?
  22. How to Specify Primary Key Name in EF-Code-First
  23. Is it possible to prevent EntityFramework 4 from overwriting customized properties?
  24. big issue in converting string to datetime using linq-to-entities
  25. Entity Framework: Duplicate Records in Many-to-Many relationship
  26. Keep Getting ‘The LINQ expression node type ‘Invoke’ is not supported in LINQ to Entities’ Exception
  27. The ObjectContext instance has been disposed and can no longer be used for operations that require a connection [duplicate]
  28. Entity Framework Code First naming conventions – back to plural table names?
  29. Should the order of LINQ query clauses affect Entity Framework performance?
  30. How can set a default value constraint with Entity Framework 6 Code First?

Leave a Comment