How to make ef core 6 support dateonly type

Preface

The last time , We found that 《DateOnly and TimeOnly Types cannot be serialized 》.

But the problem is more than that .

Problem recurrence

Suppose you have the following entity classes ：

public class User
{
    public int Id { get; set; }
    public string Name { get; set; }        
    public DateOnly Birthday { get; set; }
}

because Birthday Just the date , So we used DateOnly type .

however , In the use of EF Core 6 When stored in the database , The following error occurred ： Because the database does not DateOnly type , We use  datetime type

result DateOnly Can not be Map become datetime Database type .

heavy load OnModelCreating

According to the prompt , We've overloaded OnModelCreating Method , Find a HasColumnType Method , Used to configure the data type of the column to which the attribute is mapped when facing the relational database ：

modelBuilder.Entity<User>()
  .Property(t => t.Birthday)
    .HasColumnType("datetime");

however , No effect .

HasConversion Method

Continue to find , There's another one HasConversion Method , Used to configure properties , To convert attribute values before writing to the database and back when reading from the database ：

modelBuilder.Entity<User>()
  .Property(t => t.Birthday)
    .HasConversion(
        d => d.ToDateTime(TimeOnly.MinValue),
        d => DateOnly.FromDateTime(d));

Now? ,EF Core 6 Have been able to handle correctly DateOnly, And use datetime Database type to store it .

Conclusion

today , We introduced the use of converters to tell EF Core 6 How to deal with it DateOnly.

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