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[英]Extracting the configuration created by DbContext.OnModelCreating in IDatabaseInitializer
[英]Entity Created OnModelCreating is not accessible in DbContext
我有一个多对多关系映射,并且映射表有一个附加字段。 我创建了 ApplicationDbContext 如下:
public virtual DbSet<Country> Countries { get; set; }
public virtual DbSet<Region> Regions { get; set; }
protected override void OnModelCreating(DbModelBuilder modelBuilder)
{
modelBuilder.Entity<CountryRegionMapping>()
.HasKey(um => um.CountryRegionMappingId)
.ToTable("CountryRegionMapping");
modelBuilder.Entity<CountryRegionMapping>()
.HasRequired(um => um.Region).WithMany(g => g.CountryMappings)
.HasForeignKey(um => um.RegionId);
modelBuilder.Entity<CountryRegionMapping>()
.HasRequired(um => um.Country).WithMany(g => g.RegionMappings)
.HasForeignKey(um => um.CountryId);
base.OnModelCreating(modelBuilder);
}
我正在参考此链接来创建在映射表中有一个额外字段的多对多关系。
实体类是:
public class Country
{
public int Id { get; set; }
public string SystemOneName { get; set; }
public string SystemTwoName { get; set; }
public virtual ICollection<CountryRegionMapping> RegionMappings { get; set; }
}
public class Region
{
public int Id { get; set; }
public string SystemOneName { get; set; }
public string SystemTwoName { get; set; }
public virtual ICollection<CountryRegionMapping> CountryMappings { get; set; }
}
public class CountryRegionMapping
{
public int CountryRegionMappingId { get; set; }
public int CountryId { get; set; }
public virtual Country Country { get; set; }
public int RegionId { get; set; }
public virtual Region Region { get; set; }
public bool CheckField { get; set; }
}
当我尝试访问 Country 或 Region 表时,我可以使用 dbcontext.Regions 通过如下代码简单地访问它
ApplicationDbContext db = new ApplicationDbContext();
db.Regions.SingleOrDefault(r => r.Id == Id);
但是当我尝试访问“CountryRegionMapping”实体时,我无法通过代码访问 db.CountryRegionMapping
为什么这在 Db 上下文中不可用。 如何在多对多关系中访问此实体。
如果您想直接访问中间映射实体,请将它们作为DbSet
添加到您的上下文中,以及其他实体:
public virtual DbSet<CountryRegionMapping> CountryRegionMappings { get; set; }
public virtual DbSet<Country> Countries { get; set; }
public virtual DbSet<Region> Regions { get; set; }
然后您可以Countries
访问 Country 或Regions
一样访问它们:
ApplicationDbContext db = new ApplicationDbContext();
db.CountryRegionMappings//.SingleOrDefault, etc.
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