concept default value in category entity framework

This is an excerpt from Manning's book Entity Framework Core in Action. Login to get full access to this book.

As just described, the convention-based modeling uses default values for the SQL type, size/precision, and nullability, based on the .NET type. A common requirement is to manually set one or more of these attributes, either because you’re using an existing database or for performance or business reasons.

8.4 Setting a default value for a database column

When you first create a .NET type, it has a default value: for an int, it’s 0; for a string, it’s null, and so on. Sometimes it’s useful to set a different default value for a property; if you asked someone their favorite color, but they didn’t reply, you could provide the default string not given instead of the normal null value.

You could set the default value in .NET by using the C# 6.0 autoproperty initializer feature with code such as this:

    public string Answer { get; set; } = "not given";

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EF Core provides three ways to set a default value for database columns, which go deeper than the C# 6.0 autoproperty initializer feature: