代码之家 › 专栏 › 技术社区 › Konrad

实现接口的实体的公共配置

entity-framework-core c#

Konrad · 技术社区 · 6 年前

假设我有一些接口,比如:

public interface ISoftDeletable
{
    bool IsActive { get; set }
}

我有很多实体来实现它:

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);
}

有什么方法可以重构它以便我可以设置 HasDefaultValue 对于所有实施 ISoftDeletable 而不是像上面那样做?

我可能可以使用每个实体的默认构造函数 IsActive = true 或者创建一个基本抽象类,但我不太喜欢。

类似的问题: Ef core fluent api set all column types of interface

有更好的办法吗?

1 回复 | 直到 6 年前

Konrad 6 年前

我在这里找到了答案: GetEntityTypes: configure entity properties using the generic version of .Property<TEntity> in EF Core

除了上面的注释之外,还有一种方法可以做到这一点,而不必为每个实体调用它。这可能会被重构成一些扩展方法,正如Erndob在我的问题下的评论所提到的。

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);
        }
    }
}

解决办法是 ModelBuilder.Model.GetEntityTypes() 并查找可从 ISoftDeletable .

在我看来,这比手动配置它,甚至创建一个抽象的 IEntityTypeConfiguration<> 上课,因为你不必记得把它全部用上 等位异构体 上课。

更干净:

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;
    }
}

以及 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));
    });
}

Codemunkie 5 年前

我想做一些类似的事情,但是使用 IEntityTypeConfiguration 接口来保存我的通用配置。我最后不得不使用反射,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);
    }
}