The Fluent API HasMaxLength Method

The HasMaxLength method is applied to a property to specify a maximum number of characters or bytes for the column that the property should map to. The following example specifies that the Title column in the Books table is to be have a maximum length of 150 characters instead of the default which is unlimited:

public class SampleContext : DbContext
{
    public DbSet<Book> Books { get; set; }

    protected override void OnModelCreating(ModelBuilder modelBuilder)
    {
        modelBuilder.Entity<Book>()
            .Property(b => b.Title).HasMaxLength(150);
    }
}

public class Book
{
    public int BookId { get; set; }
    public string Title { get; set; }
    public Author Author { get; set; }
}

Data Annotations

The Data Annotations equivalents to the HasMaxLength method are the MaxLength attribute and the StringLength attribute.