问Entity Framework类中是否有"isRequired“属性？正在尝试获取模型的元数据属性

EN

// What our controller looks like: 
var maxLengthOfStrings = _db.Model
    .FindEntityType(typeof(Validation))
    .GetProperties()
    .Where(p => p.ClrType == typeof(string))
    .ToDictionary(prop => prop.Name, prop => new {
         MaxLegnth = prop.GetMaxLength(),
         // The part that is saying required doesn't exist
         // in the context
         IsRequired = prop.IsRequired()
      });

// What our db context file looks like:
modelBuilder.Entity<DeploymentEnvironment>(entity =>
            {
                entity.HasKey(e => e.Code);

                entity.Property(e => e.Code)
                    .HasMaxLength(100)
                    .ValueGeneratedNever();

                entity.Property(e => e.Name)
                    .IsRequired()
                    .HasMaxLength(200);
         });