实体框架，保存枚举集合 [英] Entity Framework, Saving a Collection of Enums

问题描述

我有一张桌子来保存联系人的电话号码.在表格中，我对每个电话号码都有电话限制.电话限制存储为枚举，但它们可以具有多个电话限制.尝试创建迁移时，出现错误

I have a table to save phone numbers for a contact. Within the table I have phone restrictions to tie to each phone number. The phone restrictions are stored as enums, but they can have multiple phone restrictions. When I try and create a migration I get the error

无法映射属性"PhoneNumber.Restrictions"，因为它的类型为"ICollection"，而不是支持的原始类型或有效的实体类型.要么显式映射此属性，或使用'[NotMapped]'属性或通过忽略此属性在'OnModelCreating'中使用'EntityTypeBuilder.Ignore'.

The property 'PhoneNumber.Restrictions' could not be mapped, because it is of type 'ICollection' which is not a supported primitive type or a valid entity type. Either explicitly map this property, or ignore it using the '[NotMapped]' attribute or by using 'EntityTypeBuilder.Ignore' in 'OnModelCreating'.

我看过一些使用标记的教程，但是上面没有太多信息/不清楚如何使用，这些教程来自5年前.

I have seen some tutorials that say to use flags, but there was not much information on it/not clear how to use and the tutorials were from 5+ years ago.

我的问题是，对于我们而言，将电话限制列表存储在Entity Framework中的最佳方法是什么?

My question is what is the best way for us to store the list of phone restrictions in Entity Framework?

代码

public class PhoneNumber 
{
   public int Id { get; set; }
   public string PhoneNumber { get; set; }
   public ICollection<PhoneRestrictions> PhoneRestrictions { get; set; }
}

public enum PhoneRestrictions
{
    None = 0,
    DaysOnly = 1,
    DoNotCallDays = 2,
    Evenings = 3,
    NoWeekends = 4
}

推荐答案

实体框架只能从技术上看到 enum 值: int .在我看来，最简单的方法是使用 Id 和 Name /创建一个简单的定义表( PhoneRestriction )Description 列，然后在 DbContext 中的 PhoneNumber 和 PhoneRestriction 之间创建多对多关系.

Entity Framework can only see an enum value for what they technically are: an int. The easiest thing to do, in my opinion, is to create a simple definition table (PhoneRestriction) with an Id and Name/Description columns, then create a many-to-many relationship between PhoneNumber and PhoneRestriction in your DbContext.

modelBuilder.Entity<PhoneNumber>()
            .HasMany(a => a.PhoneRestrictions)
            .WithMany()
            .Map(a => a.MapLeftKey("PhoneNumberId")
                       .MapRightKey("PhoneRestrictionId")
                       .ToTable("PhoneNumberPhoneRestriction"));

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