Entity Framework data generation option databasegenerated "Go"

In EF, when we build the data model, we can give the property configuration data Generation option databasegenerated, which has three enumerated values: Identity, none, and computed.

Identity: Self-growth

None: Do not process

Computed: Indicates that this column is a computed column.

In EF, if the primary key is of type int, Code first will automatically set the column self-growth when it generates the database. But if the primary key is a GUID type, we will have to set it manually.

For the following model, if we do not set self-growth, the database will be filled with zeros

public class person    {        [Key] public        Guid SocialSecurityNumber {get; set;}        public string FirstName {get; set;}        public string LastName {get; set;}    }

            var person = new Person            {                FirstName = "Rowan",                LastName = "Miller",            };            using (var context = new Breakawaycontext ())            {                context. People.add (person);                Context. SaveChanges ();            }

When you insert a second record, you get an error. Therefore, the following model settings are correct.

public class person    {        [key,databasegenerated (databasegeneratedoption.identity)] public        Guid SocialSecurityNumber {get; set;}        public string FirstName {get; set;}        public string LastName {get; set;}    }

Now let's take a look at some scenarios where configuring none is also useful. Modify the model above.

public class person    {        [Key] public        int SocialSecurityNumber {get; set;}        public string FirstName {get; set;}        public string LastName {get; set;}    }

Let's insert a record and see

   var person = new Person            {                FirstName = "Rowan",                LastName = "Miller",                SocialSecurityNumber = 12345678< c13/>};            using (var context = new Breakawaycontext ())            {                context. People.add (person);                Context. SaveChanges ();            }

stored in the database is 1, not what we want 12345678. What is this for?

Because the primary key is SocialSecurityNumber is the int type, Code first does the self-growth processing of the column in the database. At this point, we would like to insert a custom socialsecuritynumber.

So when we want to do this, we should configure the SocialSecurityNumber self-growth to none.

public class person    {        [Key, Databasegenerated (databasegeneratedoption.none)] public        int SocialSecurityNumber {get; set;}        public string FirstName {get; set;}        public string LastName {get; set;}    }

If the attribute is identified as COMPUTED,EF, the column is considered to be calculated from a different column and is not persisted to the database.

  public class person    {        [Key, Databasegenerated (databasegeneratedoption.none)] public        int SocialSecurityNumber {get; set;}        public string FirstName {get; set;}        public string LastName {get; set;}        [Databasegenerated (databasegeneratedoption.computed)]        public string Name {get; set;}    }

var person = new Person            {                FirstName = "Rowan",                LastName = "Miller",                socialsecuritynumber = 1231478,                Name = "Rowan Miller",            };            using (var context = new Breakawaycontext ())            {                context. People.add (person);                Context. SaveChanges ();            }

Looking at the database, we see that name does not store any values.

Entity Framework data generation option databasegenerated "Go"