在 EF6 中我们通常能够使用这种方式来配置 Entity。
public class AccountMap : EntityTypeConfiguration<Account>
{
public AccountMap()
{
ToTable("Account");
HasKey(a => a.Id);
Property(a => a.Username).HasMaxLength(50);
Property(a => a.Email).HasMaxLength(255);
Property(a => a.Name).HasMaxLength(255);
}
}
我们如何在 EF Core 中做，因为当我继承 EntityTypeConfiguration 的类时找不到该类。
我从 GitHub 下载了 EF Core 原始源代码，但找不到。有人可以帮忙吗？
由于 EF Core 2.0 有IEntityTypeConfiguration<TEntity>. 你可以像这样使用它：
class CustomerConfiguration : IEntityTypeConfiguration<Customer>
{
public void Configure(EntityTypeBuilder<Customer> builder)
{
builder.HasKey(c => c.AlternateKey);
builder.Property(c => c.Name).HasMaxLength(200);
}
}
...
// OnModelCreating
builder.ApplyConfiguration(new CustomerConfiguration());
可以在此处找到有关此功能和 2.0 中引入的其他新功能的更多信息。
您可以通过一些简单的附加类型来实现这一点：
internal static class ModelBuilderExtensions
{
public static void AddConfiguration<TEntity>(
this ModelBuilder modelBuilder,
DbEntityConfiguration<TEntity> entityConfiguration) where TEntity : class
{
modelBuilder.Entity<TEntity>(entityConfiguration.Configure);
}
}
internal abstract class DbEntityConfiguration<TEntity> where TEntity : class
{
public abstract void Configure(EntityTypeBuilder<TEntity> entity);
}
用法：
internal class UserConfiguration : DbEntityConfiguration<UserDto>
{
public override void Configure(EntityTypeBuilder<UserDto> entity)
{
entity.ToTable("User");
entity.HasKey(c => c.Id);
entity.Property(c => c.Username).HasMaxLength(255).IsRequired();
// etc.
}
}
protected override void OnModelCreating(ModelBuilder modelBuilder)
{
base.OnModelCreating(modelBuilder);
modelBuilder.AddConfiguration(new UserConfiguration());
}
在 EF7 中，您在要实现的 DbContext 类上覆盖 OnModelCreating。
protected override void OnModelCreating(ModelBuilder modelBuilder)
{
base.OnModelCreating(modelBuilder);
modelBuilder.Entity<Account>()
.ForRelational(builder => builder.Table("Account"))
.Property(value => value.Username).MaxLength(50)
.Property(value => value.Email).MaxLength(255)
.Property(value => value.Name).MaxLength(255);
}
这是使用当前最新的 beta 8。试试这个：
public class AccountMap
{
public AccountMap(EntityTypeBuilder<Account> entityBuilder)
{
entityBuilder.HasKey(x => x.AccountId);
entityBuilder.Property(x => x.AccountId).IsRequired();
entityBuilder.Property(x => x.Username).IsRequired().HasMaxLength(50);
}
}
然后在您的 DbContext 中：
protected override void OnModelCreating(ModelBuilder modelBuilder)
{
base.OnModelCreating(modelBuilder);
new AccountMap(modelBuilder.Entity<Account>());
}
从 EF Core 2.2 开始，您可以在继承自 DbContext 类的类中的方法 OnModelCreating 的一行中添加所有配置（类，实现 IEntityTypeConfiguration 接口）
protected override void OnModelCreating(ModelBuilder modelBuilder)
{
//this will apply configs from separate classes which implemented IEntityTypeConfiguration<T>
modelBuilder.ApplyConfigurationsFromAssembly(Assembly.GetExecutingAssembly());
}
而且，正如在上一个答案中提到的，从 EF Core 2.0 开始，您可以实现接口 IEntityTypeConfiguration，在 Configure 方法中使用 FluentAPI 设置映射配置。
public class QuestionAnswerConfig : IEntityTypeConfiguration<QuestionAnswer>
{
public void Configure(EntityTypeBuilder<QuestionAnswer> builder)
{
builder
.HasKey(bc => new { bc.QuestionId, bc.AnswerId });
builder
.HasOne(bc => bc.Question)
.WithMany(b => b.QuestionAnswers)
.HasForeignKey(bc => bc.QuestionId);
builder
.HasOne(bc => bc.Answer)
.WithMany(c => c.QuestionAnswers)
.HasForeignKey(bc => bc.AnswerId);
}
}
您可以使用反射来做与它们在 EF6 中的工作方式非常相似的事情，每个实体都有一个单独的映射类。这适用于 RC1 决赛：
首先，为您的映射类型创建一个接口：
public interface IEntityTypeConfiguration<TEntityType> where TEntityType : class
{
void Map(EntityTypeBuilder<TEntityType> builder);
}
然后为每个实体创建一个映射类，例如为一个Person类：
public class PersonMap : IEntityTypeConfiguration<Person>
{
public void Map(EntityTypeBuilder<Person> builder)
{
builder.HasKey(x => x.Id);
builder.Property(x => x.Name).IsRequired().HasMaxLength(100);
}
}
现在，OnModelCreating您的DbContext实现中的反射魔法：
protected override void OnModelCreating(ModelBuilder builder)
{
base.OnModelCreating(builder);
// Interface that all of our Entity maps implement
var mappingInterface = typeof(IEntityTypeConfiguration<>);
// Types that do entity mapping
var mappingTypes = typeof(DataContext).GetTypeInfo().Assembly.GetTypes()
.Where(x => x.GetInterfaces().Any(y => y.GetTypeInfo().IsGenericType && y.GetGenericTypeDefinition() == mappingInterface));
// Get the generic Entity method of the ModelBuilder type
var entityMethod = typeof(ModelBuilder).GetMethods()
.Single(x => x.Name == "Entity" &&
x.IsGenericMethod &&
x.ReturnType.Name == "EntityTypeBuilder`1");
foreach (var mappingType in mappingTypes)
{
// Get the type of entity to be mapped
var genericTypeArg = mappingType.GetInterfaces().Single().GenericTypeArguments.Single();
// Get the method builder.Entity<TEntity>
var genericEntityMethod = entityMethod.MakeGenericMethod(genericTypeArg);
// Invoke builder.Entity<TEntity> to get a builder for the entity to be mapped
var entityBuilder = genericEntityMethod.Invoke(builder, null);
// Create the mapping type and do the mapping
var mapper = Activator.CreateInstance(mappingType);
mapper.GetType().GetMethod("Map").Invoke(mapper, new[] { entityBuilder });
}
}
这就是我在我目前正在从事的项目中所做的事情。
public interface IEntityMappingConfiguration<T> where T : class
{
void Map(EntityTypeBuilder<T> builder);
}
public static class EntityMappingExtensions
{
public static ModelBuilder RegisterEntityMapping<TEntity, TMapping>(this ModelBuilder builder)
where TMapping : IEntityMappingConfiguration<TEntity>
where TEntity : class
{
var mapper = (IEntityMappingConfiguration<TEntity>)Activator.CreateInstance(typeof (TMapping));
mapper.Map(builder.Entity<TEntity>());
return builder;
}
}
用法：
在您的 Context 的 OnModelCreating 方法中：
protected override void OnModelCreating(ModelBuilder builder)
{
base.OnModelCreating(builder);
builder
.RegisterEntityMapping<Card, CardMapping>()
.RegisterEntityMapping<User, UserMapping>();
}
示例映射类：
public class UserMapping : IEntityMappingConfiguration<User>
{
public void Map(EntityTypeBuilder<User> builder)
{
builder.ToTable("User");
builder.HasKey(m => m.Id);
builder.Property(m => m.Id).HasColumnName("UserId");
builder.Property(m => m.FirstName).IsRequired().HasMaxLength(64);
builder.Property(m => m.LastName).IsRequired().HasMaxLength(64);
builder.Property(m => m.DateOfBirth);
builder.Property(m => m.MobileNumber).IsRequired(false);
}
}
为了利用 Visual Studio 2015 的折叠行为，我喜欢做的另一件事是为名为“用户”的实体，将映射文件命名为“User.Mapping.cs”，Visual Studio 将在解决方案资源管理器中折叠文件使其包含在实体类文件下。
我以这个解决方案结束：
public interface IEntityMappingConfiguration
{
void Map(ModelBuilder b);
}
public interface IEntityMappingConfiguration<T> : IEntityMappingConfiguration where T : class
{
void Map(EntityTypeBuilder<T> builder);
}
public abstract class EntityMappingConfiguration<T> : IEntityMappingConfiguration<T> where T : class
{
public abstract void Map(EntityTypeBuilder<T> b);
public void Map(ModelBuilder b)
{
Map(b.Entity<T>());
}
}
public static class ModelBuilderExtenions
{
private static IEnumerable<Type> GetMappingTypes(this Assembly assembly, Type mappingInterface)
{
return assembly.GetTypes().Where(x => !x.IsAbstract && x.GetInterfaces().Any(y => y.GetTypeInfo().IsGenericType && y.GetGenericTypeDefinition() == mappingInterface));
}
public static void AddEntityConfigurationsFromAssembly(this ModelBuilder modelBuilder, Assembly assembly)
{
var mappingTypes = assembly.GetMappingTypes(typeof (IEntityMappingConfiguration<>));
foreach (var config in mappingTypes.Select(Activator.CreateInstance).Cast<IEntityMappingConfiguration>())
{
config.Map(modelBuilder);
}
}
}
样品用途：
public abstract class PersonConfiguration : EntityMappingConfiguration<Person>
{
public override void Map(EntityTypeBuilder<Person> b)
{
b.ToTable("Person", "HumanResources")
.HasKey(p => p.PersonID);
b.Property(p => p.FirstName).HasMaxLength(50).IsRequired();
b.Property(p => p.MiddleName).HasMaxLength(50);
b.Property(p => p.LastName).HasMaxLength(50).IsRequired();
}
}
和
protected override void OnModelCreating(ModelBuilder modelBuilder)
{
modelBuilder.AddEntityConfigurationsFromAssembly(GetType().Assembly);
}
只需实现 IEntityTypeConfiguration
public abstract class EntityTypeConfiguration<TEntity> : IEntityTypeConfiguration<TEntity> where TEntity : class
{
public abstract void Configure(EntityTypeBuilder<TEntity> builder);
}
然后将其添加到您的实体上下文
public class ProductContext : DbContext, IDbContext
{
public ProductContext(DbContextOptions<ProductContext> options)
: base((DbContextOptions)options)
{
}
protected override void OnModelCreating(ModelBuilder modelBuilder)
{
base.OnModelCreating(modelBuilder);
modelBuilder.ApplyConfiguration(new ProductMap());
}
public DbSet<Entities.Product> Products { get; set; }
}
在 Entity Framework Core 2.0 中：
我接受了 Cocowalla 的回答并将其改编为 v2.0：
public static class ModelBuilderExtenions
{
private static IEnumerable<Type> GetMappingTypes(this Assembly assembly, Type mappingInterface)
{
return assembly.GetTypes().Where(x => !x.IsAbstract && x.GetInterfaces().Any(y => y.GetTypeInfo().IsGenericType && y.GetGenericTypeDefinition() == mappingInterface));
}
public static void AddEntityConfigurationsFromAssembly(this ModelBuilder modelBuilder, Assembly assembly)
{
// Types that do entity mapping
var mappingTypes = assembly.GetMappingTypes(typeof(IEntityTypeConfiguration<>));
// Get the generic Entity method of the ModelBuilder type
var entityMethod = typeof(ModelBuilder).GetMethods()
.Single(x => x.Name == "Entity" &&
x.IsGenericMethod &&
x.ReturnType.Name == "EntityTypeBuilder`1");
foreach (var mappingType in mappingTypes)
{
// Get the type of entity to be mapped
var genericTypeArg = mappingType.GetInterfaces().Single().GenericTypeArguments.Single();
// Get the method builder.Entity<TEntity>
var genericEntityMethod = entityMethod.MakeGenericMethod(genericTypeArg);
// Invoke builder.Entity<TEntity> to get a builder for the entity to be mapped
var entityBuilder = genericEntityMethod.Invoke(modelBuilder, null);
// Create the mapping type and do the mapping
var mapper = Activator.CreateInstance(mappingType);
mapper.GetType().GetMethod("Configure").Invoke(mapper, new[] { entityBuilder });
}
}
}
它在 DbContext 中使用如下：
protected override void OnModelCreating(ModelBuilder modelBuilder)
{
modelBuilder.AddEntityConfigurationsFromAssembly(GetType().Assembly);
}
这就是您为实体创建实体类型配置的方式：
public class UserUserRoleEntityTypeConfiguration : IEntityTypeConfiguration<UserUserRole>
{
public void Configure(EntityTypeBuilder<UserUserRole> builder)
{
builder.ToTable("UserUserRole");
// compound PK
builder.HasKey(p => new { p.UserId, p.UserRoleId });
}
}
public class Student
{
public int Id { get; set; }
public string Name { get; set; }
public int RollNumber { get; set; }
public string Address { get; set; }
}
public class StudentMapper : IEntityTypeConfiguration<Student>
{
public void Configure(EntityTypeBuilder<Student> builder)
{
builder.ToTable("tbl_Students");
builder.HasKey(x => x.Id);
builder.Property(x => x.Address)
.HasMaxLength(250);
builder.Property(x => x.Name)
.HasMaxLength(50);
builder.Property(x => x.Name).HasColumnName("varchar_name");
}
}
public class DataContext : DbContext
{
public DataContext(DbContextOptions options): base(options)
{
}
public DbSet<Student> Students { get; set; }
//DbSets
protected override void OnModelCreating(ModelBuilder modelBuilder) {
//for fluent API approach and also we can create a separate mapper for each entity
#region student
modelBuilder.ApplyConfiguration(new StudentMapper());
#endregion
}
}
在 ef core 中，我们必须使用 IEntityTypeConfiguration 而不是 EntityTypeConfiguration，在这种情况下，我们可以完全访问 DbContext modelBuilder，并且我们可以使用 fluent api，但在 ef core 中，这个 api 与以前的版本略有不同。您可以在以下位置找到有关 ef 核心模型配置的更多详细信息
https://www.learnentityframeworkcore.com/configuration/fluent-api
那么这里是增强 EF7 Github 存储库的问题：https ://github.com/aspnet/EntityFramework/issues/2805
您可以直接在那里跟踪问题，尽管它仍然只是在未指定优先级的积压中。
我采用了与 Microsoft 实现 ForSqlServerToTable 的方式类似的方法
使用扩展方法...
如果要在多个文件中使用相同的类名，则需要 partial标志
public class ConsignorUser
{
public int ConsignorId { get; set; }
public string UserId { get; set; }
public virtual Consignor Consignor { get; set; }
public virtual User User { get; set; }
}
public static partial class Entity_FluentMappings
{
public static EntityTypeBuilder<ConsignorUser> AddFluentMapping<TEntity> (
this EntityTypeBuilder<ConsignorUser> entityTypeBuilder)
where TEntity : ConsignorUser
{
entityTypeBuilder.HasKey(x => new { x.ConsignorId, x.UserId });
return entityTypeBuilder;
}
}
然后在 DataContext OnModelCreating中调用每个扩展...
public class DataContext : IdentityDbContext<User>
{
protected override void OnModelCreating(ModelBuilder builder)
{
base.OnModelCreating(builder);
// Customize the ASP.NET Identity model and override the defaults if needed.
// For example, you can rename the ASP.NET Identity table names and more.
// Add your customizations after calling base.OnModelCreating(builder);
builder.Entity<ConsignorUser>().AddFluentMapping<ConsignorUser>();
builder.Entity<DealerUser>().AddFluentMapping<DealerUser>();
}
这样，我们将遵循其他构建器方法使用的相同模式。
你有什么事吗？
我有一个项目，允许您配置外部的DbContext.OnModelCreating实体您在一个单独的类中配置每个实体，该类继承自StaticDotNet.EntityFrameworkCore.ModelConfiguration.EntityTypeConfiguration
首先，您需要创建一个继承自StaticDotNet.EntityFrameworkCore.ModelConfiguration.EntityTypeConfiguration<TEntity>您TEntity要配置的类的类。
using StaticDotNet.EntityFrameworkCore.ModelConfiguration;
using Microsoft.EntityFrameworkCore.Metadata.Builders;
public class ExampleEntityConfiguration
: EntityTypeConfiguration<ExampleEntity>
{
public override void Configure( EntityTypeBuilder<ExampleEntity> builder )
{
//Add configuration just like you do in DbContext.OnModelCreating
}
}
然后在您的 Startup 类中，您只需告诉 Entity Framework 在配置 DbContext 时在哪里可以找到所有配置类。
using StaticDotNet.EntityFrameworkCore.ModelConfiguration;
public void ConfigureServices(IServiceCollection services)
{
Assembly[] assemblies = new Assembly[]
{
// Add your assembiles here.
};
services.AddDbContext<ExampleDbContext>( x => x
.AddEntityTypeConfigurations( assemblies )
);
}
还有一个使用提供程序添加类型配置的选项。该 repo 包含有关如何使用它的完整文档。
https://github.com/john-t-white/StaticDotNet.EntityFrameworkCore.ModelConfiguration
我对吗？
public class SmartModelBuilder<T> where T : class {
private ModelBuilder _builder { get; set; }
private Action<EntityTypeBuilder<T>> _entityAction { get; set; }
public SmartModelBuilder(ModelBuilder builder, Action<EntityTypeBuilder<T>> entityAction)
{
this._builder = builder;
this._entityAction = entityAction;
this._builder.Entity<T>(_entityAction);
}
}
我可以通过配置：
protected override void OnModelCreating(ModelBuilder builder)
{
base.OnModelCreating(builder);
// Customize the ASP.NET Identity model and override the defaults if needed.
// For example, you can rename the ASP.NET Identity table names and more.
// Add your customizations after calling base.OnModelCreating(builder);
new SmartModelBuilder<Blog>(builder, entity => entity.Property(b => b.Url).Required());
}