Model backing a DB Context has changed; Consider Code First Migrations

[Origin]: http://stackoverflow.com/questions/14948205/model-backing-a-db-context-has-changed-consider-code-first-migrations

EF codefirst will look at your DbContext, and discover all the entity collections declared in it(and also look at entities related to those entities via navigation properties). It will then look at the database you gave it a connection string to, and make sure all of the tables there match the structure of your entities in model. If they do not match, then it cannot read/write to those tables. Anytime you create a new database, or if you change something about the entity class declarations, such as adding properties or changing data types, then it will detect that the model and the database are not in sync. By default it will simply give you the above error. Usually during development what you want to happen is for the database to be recreated(wiping any data) and generated again from your new model structure.

To do that, see “RecreateDatabaseIfModelChanges Feature” in this article:http://weblogs.asp.net/scottgu/archive/2010/07/16/code-first-development-with-entity-framework-4.aspx

You basically need to provide a database initializer that inherits from RecreateDatabaseIfModelChanges.

Once you go to production and no longer want to lose data, then you’d remove this initializer and instead use Database Migrations so that you can deploy changes without losing data.

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To solve this error write the the following code in Application_Start() Method in Global.asax.cs file

Database.SetInitializer<MyDbContext>(null);
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How can I resolve this error: Loading the include file ‘EF.Utility.CS.ttinclude’ returned a null or empty string

[Originally posted by]: http://stackoverflow.com/questions/14999633/how-can-i-resolve-this-error-loading-the-include-file-ef-utility-cs-ttinclude

How can I resolve these errors:

  1. Loading the include file ‘EF.Utility.CS.ttinclude’ returned a null or empty string.
  2. Value does not fall within the expected range.

Tools Used: VS 2012, Entity Framework 5.0.0, T4MVCExtensions 3.5.0, .NET Framework 4.5

I’ve been using EF and T4 templates in a project within a large MVC solution without incident. Now, when I right-click on the edmx diagram, EF responds with the message: Value does not fall within the expected range. When I compile the EF project it responds with these messages:

  1. Loading the include file ‘EF.Utility.CS.ttinclude’ returned a null or empty string. The transformation will not be run. C:\Projects\NSAForms\NSAForms\NSAFormsEDM\NSAFormsEntities.tt
  2. Failed to resolve include text for file:C:\Projects\NSAForms\NSAForms\NSAFormsEDM\EF.Utility.CS.ttinclude C:\Projects\NSAForms\NSAForms\NSAFormsEDM\NSAFormsEntities.tt

Every table in the database has a primary key. I’m struck by how suddenly this issue appeared. Does anyone have some suggestions how to resolve this issue?

Thanks in advance,

Arnold

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I had very similar issue and I tried with VS2012 and VS2013.

After reinstalling Entity Framework 6 Tools for Visual Studio 2012 http://www.microsoft.com/en-us/download/confirmation.aspx?id=40762 every thing went back to normal.

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