假設我有一些界面，例如：public interface ISoftDeletable{ bool IsActive { get; set }}我有很多實體實現(xiàn)了它：public class Entity1 : ISoftDeletable{ public int Id { get; set } public bool IsActive { get; set; }}public class Entity2 : ISoftDeletable{ public int Id { get; set } public bool IsActive { get; set; }}在OnModelCreating：protected override void OnModelCreating(ModelBuilder modelBuilder){ modelBuilder.Entity<Entity1>().Property(e => e.IsActive).HasDefaultValue(true); modelBuilder.Entity<Entity2>().Property(e => e.IsActive).HasDefaultValue(true);}有什么方法可以重構它，以便我可以HasDefaultValue為所有實體進行設置，ISoftDeletable而不是像上面那樣做？我可能可以使用每個實體的默認構造函數(shù)解決這個特定情況，IsActive = true甚至創(chuàng)建一個基本抽象類，但我不太喜歡它。有沒有更好的辦法？
2 回答
慕虎7371278
TA貢獻1802條經(jīng)驗 獲得超4個贊
我在這里找到了一些答案：GetEntityTypes: configure entity properties using the generic version of .Property<TEntity> in EF Core
除了上面的評論之外，還有一種方法可以不用為每個實體調(diào)用它。這可能可以重構為一些擴展方法，正如 Erndob 在我的問題下的評論所提到的。
protected override void OnModelCreating(ModelBuilder modelBuilder)
{
foreach (var entityType in modelBuilder.Model.GetEntityTypes())
{
if (typeof(ISoftDeletable).IsAssignableFrom(entityType.ClrType))
{
modelBuilder.Entity(entityType.ClrType).Property<bool>(nameof(ISoftDeletable.IsActive)).HasDefaultValue(true);
}
}
}
解決方案是使用ModelBuilder.Model.GetEntityTypes()和查找可從ISoftDeletable.
在我看來，這比手動配置它甚至創(chuàng)建一個抽象IEntityTypeConfiguration<>類要好得多，因為您不必記住對所有ISoftDeletable類都使用它。
更干凈的外觀：
public static class ModelBuilderExtensions
{
public static ModelBuilder EntitiesOfType<T>(this ModelBuilder modelBuilder,
Action<EntityTypeBuilder> buildAction) where T : class
{
return modelBuilder.EntitiesOfType(typeof(T), buildAction);
}
public static ModelBuilder EntitiesOfType(this ModelBuilder modelBuilder, Type type,
Action<EntityTypeBuilder> buildAction)
{
foreach (var entityType in modelBuilder.Model.GetEntityTypes())
if (type.IsAssignableFrom(entityType.ClrType))
buildAction(modelBuilder.Entity(entityType.ClrType));
return modelBuilder;
}
}
并且OnModelCreating：
protected override void OnModelCreating(ModelBuilder modelBuilder)
{
modelBuilder.EntitiesOfType<ISoftDeletable>(builder =>
{
builder.Property<bool>(nameof(ISoftDeletable.IsActive)).HasDefaultValue(true);
// query filters :)
var param = Expression.Parameter(builder.Metadata.ClrType, "p");
var body = Expression.Equal(Expression.Property(param, nameof(ISoftDeletable.IsActive)), Expression.Constant(true));
builder.HasQueryFilter(Expression.Lambda(body, param));
});
}
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我想做類似的事情，但使用IEntityTypeConfiguration界面來保存我的通用配置。我最終不得不使用反射，但它有效：
Interface:
public interface IHasDisplayId
{
Guid DisplayId { get; }
}
EntityTypeConfig:
public class HasDisplayIdEntityTypeConfiguration<T> : IEntityTypeConfiguration<T> where T : class, IHasDisplayId
{
public void Configure(EntityTypeBuilder<T> builder)
{
builder.Property(e => e.DisplayId).IsRequired();
builder.HasIndex(e => e.DisplayId);
}
}
Extension method:
public static ModelBuilder ApplyConfiguration<T>(this ModelBuilder modelBuilder, Type configurationType, Type entityType)
{
if (typeof(T).IsAssignableFrom(entityType))
{
// Build IEntityTypeConfiguration type with generic type parameter
var configurationGenericType = configurationType.MakeGenericType(entityType);
// Create an instance of the IEntityTypeConfiguration implementation
var configuration = Activator.CreateInstance(configurationGenericType);
// Get the ApplyConfiguration method of ModelBuilder via reflection
var applyEntityConfigurationMethod = typeof(ModelBuilder)
.GetMethods()
.Single(e => e.Name == nameof(ModelBuilder.ApplyConfiguration)
&& e.ContainsGenericParameters
&& e.GetParameters().SingleOrDefault()?.ParameterType.GetGenericTypeDefinition() == typeof(IEntityTypeConfiguration<>));
// Create a generic ApplyConfiguration method with our entity type
var target = applyEntityConfigurationMethod.MakeGenericMethod(entityType);
// Invoke ApplyConfiguration, passing our IEntityTypeConfiguration instance
target.Invoke(modelBuilder, new[] { configuration });
}
return modelBuilder;
}
Usage:
protected override void OnModelCreating(ModelBuilder modelBuilder)
{
foreach (var entityType in modelBuilder.Model.GetEntityTypes())
{
modelBuilder.ApplyConfiguration<IHasDisplayId>(typeof(HasDisplayIdEntityTypeConfiguration<>), entityType.ClrType);
}
}
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