如何在实体框架流利的api中的所有字段上设置默认长度？

Question

Is it possible to set default length of all string fields (unless I say otherwise)? At the moment it really bugs me to go and add something like

modelBuilder.Entity<Game>().Property(x => x.YardLine).HasMaxLength(256); to each and every string field, just to avoid having nvarchar(max) on all my strings columns in the database.

Answer 1

You can use something called Custom Code First Conventions , but only if you're using Entity Framework 6+.

As @ranquild mentions , you can use

modelBuilder.Properties<string>().Configure(p => p.HasMaxLength(256));

to configure the default maximum length for all string properties. You can even filter which properties to apply your configuration to:

modelBuilder.Properties<string>()
    .Where(p => someCondition)
    .Configure(p => p.HasMaxLength(256));

Finally, any configuration on the entity type itself would take precedence. For example:

modelBuilder.Entity<EntityType>().Property(x => x.StringProperty)
    .HasMaxLength(DifferentMaxLength);

Answer 2

添加：

modelBuilder.Properties<string>().Configure(p => p.HasMaxLength(256));