Nullable property to entity field Entity Framework through Code First

Question

Using the data annotation Required like so    Required  public int somefield  get  set     Will set somefield to Not Null in database  How can I set somefield to allow NULLs   I tried setting it through SQL Server Management Studio but Entity Framework set it back to Not Null

User · Answer

The other option is to tell EF to allow the column to be null:

protected override void OnModelCreating(DbModelBuilder modelBuilder)
{
        modelBuilder.Entity<SomeObject>().Property(m => m.somefield).IsOptional();            
        base.OnModelCreating(modelBuilder);
}

This code should be in the object that inherits from DbContext.

User · Answer

Jon s answer didn t work for me as I got a compiler error CS0453  C  The type must be a non-nullable value type in order to use it as parameter  T  in the generic type or method  This worked for me though   protected override void OnModelCreating DbModelBuilder modelBuilder        modelBuilder Entity lt SomeObject gt    HasOptional m   gt  m somefield       base OnModelCreating modelBuilder

User · Answer

Just omit the  Required  attribute from the string somefield property  This will make it create a NULLable column in the db   To make int types allow NULLs in the database  they must be declared as nullable ints in the model      an int can never be null  so it will be created as NOT NULL in db public int someintfield   get  set        to have a nullable int  you need to declare it as an int     or as a System Nullable lt int gt  public int  somenullableintfield   get  set    public System Nullable lt int gt  someothernullableintfield   get  set

User · Answer

In Ef  net core there are two options that you can do  first with data annotations  public class Blog       public int BlogId   get  set         Required      public string Url   get  set       Or with fluent api  class MyContext   DbContext       public DbSet lt Blog gt  Blogs   get  set         protected override void OnModelCreating ModelBuilder modelBuilder                modelBuilder Entity lt Blog gt                 Property b   gt  b Url               IsRequired false   optinal case              IsRequired    required case                        public class Blog       public int BlogId   get  set        public string Url   get  set       There are more details here

[entity-framework] Nullable property to entity field, Entity Framework through Code First

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