当只有1条记录时，定义没有主键的实体

Question

I have an Entity Framework Code First MVC3 solution where I have an entity named Settings where I only have 1 record in it. This entity is used to store general settings for the solution.

public class Settings
{
    public bool   CommunicationActivated { get; set; }
    public string CommunicationMessage { get; set; }
    ...
}

When I run the solution, I got the error: System.Data.Edm.EdmEntityType: : EntityType 'Settings' has no key defined. Define the key for this EntityType.

My question : is it possible to have an entity without key defined? Is it a good idea for an entity with only one record?

Thanks.

Answer 1

I recommend that you just add a new column:

ID INT NOT NULL IDENTITY PRIMARY KEY

This does no harm and allows you to work with the tools, not against them.

You can even ensure that the table only has one record: Set the ID field manually to 1 and add a check constraint for (ID = 1) .