If a database table in Entity Framework 6 has a column that does not exist in the entity, can we guarantee that the column will just be ignored and will not negatively impact processing?

Question

Is there any official document that can guarantee that adding a column to a SQL Server table referenced by EF6 in an existing system will not affect the system?　

Answer 1

Hi @Takayoshi Enomoto ,

If you don’t make changes to the entity class (i.e., you don’t add any new properties), Entity Framework 6 (EF6) will ignore any new columns that exist in the database but are not represented in the entity.

Best Regards.

Jiachen Li

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Answer 2

But if the column does not allow null, or does not have a default value, EF inserts will fail.

Answer 3

In fact, if you're following the DDD concept of bounded contexts then you really shouldn't be adding any columns to your entities that your app doesn't actually need. It wastes time loading and saving the entity (creating a proxy, state management, etc) and clutters your code. Furthermore if you eventually want to get rid of that column then you have to open your app to remove the reference even though the app never used it to begin with.

Of course if the column is required and doesn't have a default value then you have to insert a value into it and therefore EF has to know about it. But that would be a breaking change to any app that inserts values into the table, irrelevant of EF.

Answer 4

Is there any official document that can guarantee that adding a column to a SQL Server table referenced by EF6 in an existing system will not affect the system?

Are you saying that you have an existing application which uses EF6 to do some operation of the existing database table and you want to add a filed to the existing database table?

If so, I believe that there is no such official document. It is not possible for anybody to guarantee since nobody knows your details (i.e., schema of table, added field, usage of table in your application).

Can you tell us the details? For example (only example though, please write your case),

(1) Entity Data Model was created using the Visual Studio based on the Microsoft sample database Northwind (probably everybody knows its schema):

(2) Controller and views of ASP.NET MVC5 were created for CRUD operations of the Products table using ASP.NET scaffolding available in Visual studio.

(3) You want add field [Remark], nvarchar(255), NOT NULL.

(4) Your question: above (3) affects the CRUD operation of the MVC5 application?