EF Core：带有阴影属性和查询过滤器的软删除

Question

我创建了一个界面来尝试进行软删除，混合阴影属性和查询过滤器。 但它不起作用。

public interface IDeletableEntity {}

然后在我的 model 构建器中

 builder.Model.GetEntityTypes()
                .Where(entityType => typeof(IDeletableEntity).IsAssignableFrom(entityType.ClrType))
                .ToList()
                .ForEach(entityType =>
                {
                    builder.Entity(entityType.ClrType).Property<Boolean>("IsDeleted");
                    builder.Entity(entityType.ClrType).HasQueryFilter(e => EF.Property<Boolean>(e, "IsDeleted") == false);
                });

但是带有查询过滤器的行无法编译。 我得到的错误是“无法将 lambda 表达式转换为类型 'lambda 表达式'，因为它不是委托类型”

如果我这样做，它会起作用。

builder.Entity<MyEntity>().HasQueryFilter(m => EF.Property<Boolean>(m, "IsDeleted") == false);

有什么办法可以做到这一点？ 这是为了在我想使用软删除实体的每个实体中拥有一个与 IDeletableEntity 的接口并且不必这样做

提前谢谢了，

Answer 1

非泛型EntityTypeBuilder （与泛型EntityTypeBuilder<TEntity>相对）的HasQueryFilter几乎无法使用，因为没有简单的方法可以创建预期的LambdaExpression 。

一种解决方案是使用Expression类方法手动构建 lambda 表达式：

.ForEach(entityType =>
{
    builder.Entity(entityType.ClrType).Property<Boolean>("IsDeleted");
    var parameter = Expression.Parameter(entityType.ClrType, "e");
    var body = Expression.Equal(
        Expression.Call(typeof(EF), nameof(EF.Property), new[] { typeof(bool) }, parameter, Expression.Constant("IsDeleted")),
    Expression.Constant(false));
    builder.Entity(entityType.ClrType).HasQueryFilter(Expression.Lambda(body, parameter));
});

另一种是使用原型表达式

Expression<Func<object, bool>> filter = 
    e => EF.Property<bool>(e, "IsDeleted") == false;

并使用参数替换器将参数与实际类型绑定：

.ForEach(entityType =>
{
    builder.Entity(entityType.ClrType).Property<Boolean>("IsDeleted");
    var parameter = Expression.Parameter(entityType.ClrType, "e");
    var body = filter.Body.ReplaceParameter(filter.Parameters[0], parameter);
    builder.Entity(entityType.ClrType).HasQueryFilter(Expression.Lambda(body, parameter));
});

其中ReplaceParameter是我用于表达式树操作的自定义助手扩展方法之一：

public static partial class ExpressionUtils
{
    public static Expression ReplaceParameter(this Expression expr, ParameterExpression source, Expression target) =>
        new ParameterReplacer { Source = source, Target = target }.Visit(expr);

    class ParameterReplacer : System.Linq.Expressions.ExpressionVisitor
    {
        public ParameterExpression Source;
        public Expression Target;
        protected override Expression VisitParameter(ParameterExpression node) => node == Source ? Target : node;
    }
}

但我认为最自然的解决方案是将配置代码移动到通用方法中并通过反射调用它。 例如：

static void ConfigureSoftDelete<T>(ModelBuilder builder)
    where T : class, IDeletableEntity
{
    builder.Entity<T>().Property<Boolean>("IsDeleted");
    builder.Entity<T>().HasQueryFilter(e => EF.Property<bool>(e, "IsDeleted") == false);
}

接着

.ForEach(entityType => GetType()
    .GetMethod(nameof(ConfigureSoftDelete), BindingFlags.NonPublic | BindingFlags.Static)
    .MakeGenericMethod(entityType.ClrType)
    .Invoke(null, new object[] { builder })
);

Answer 2

我为我的答案找到了一个简单的解决方案；-)。 无论如何，谢谢伊万斯托耶夫

界面是：

public interface IDeletableEntity
{
    bool IsDeleted { get; }
}

在您的模型生成器配置中：

builder.Model.GetEntityTypes()
                       .Where(entityType => typeof(IDeletableEntity).IsAssignableFrom(entityType.ClrType))
                       .ToList()
                       .ForEach(entityType =>
                       {
                           builder.Entity(entityType.ClrType)
                           .HasQueryFilter(ConvertFilterExpression<IDeletableEntity>(e => !e.IsDeleted, entityType.ClrType));
                       });

你需要转换filterExpression

private static LambdaExpression ConvertFilterExpression<TInterface>(
                            Expression<Func<TInterface, bool>> filterExpression,
                            Type entityType)
                {
                    var newParam = Expression.Parameter(entityType);
                    var newBody = ReplacingExpressionVisitor.Replace(filterExpression.Parameters.Single(), newParam, filterExpression.Body);

                    return Expression.Lambda(newBody, newParam);
                }

Answer 3

@SamazoOo 的答案的一个小改进。 您可以编写扩展方法以使其更加一致。

public static EntityTypeBuilder HasQueryFilter<T>(this EntityTypeBuilder entityTypeBuilder, Expression<Func<T, bool>> filterExpression)
    {
        var param = Expression.Parameter(entityTypeBuilder.Metadata.ClrType);
        var body = ReplacingExpressionVisitor.Replace(filterExpression.Parameters.Single(), param, filterExpression.Body);

        var lambdaExp = Expression.Lambda(body, param);

        return entityTypeBuilder.HasQueryFilter(lambdaExp);
    }

Answer 4

这对我来说不起作用，.net core 3.1，所以我尝试了以下有点相似的方法：

// fetch entity types by reflection then: 

 softDeletedEntityTypes.ForEach(entityType =>
            {
                modelBuilder.Entity(entityType, builder =>
                {
                    builder.Property<bool>("IsDeleted");
                    builder.HasQueryFilter(GenerateQueryFilterExpression(entityType));
                });
            });


 private static LambdaExpression GenerateQueryFilterExpression(Type entityType)
        {            
             // the following lambda expression should be generated
             // e => !EF.Property<bool>(e, "IsDeleted")); 

            var parameter = Expression.Parameter(entityType, "e"); // e =>

            var fieldName = Expression.Constant("IsDeleted", typeof(string)); // "IsDeleted"

            // EF.Property<bool>(e, "IsDeleted")
            var genericMethodCall = Expression.Call(typeof(EF), "Property", new[] {typeof(bool)}, parameter, fieldName);

            // !EF.Property<bool>(e, "IsDeleted"))
            var not = Expression.Not(genericMethodCall);

            // e => !EF.Property<bool>(e, "IsDeleted"));
            var lambda = Expression.Lambda(not, parameter);
        }

Answer 5

我所做的是

builder.Model.GetEntityTypes()
           .Where(p => typeof(IDeletableEntity).IsAssignableFrom(p.ClrType))
           .ToList()
            .ForEach(entityType =>
            {
                builder.Entity(entityType.ClrType)
                .HasQueryFilter(ConvertFilterExpression<IDeletableEntity>(e => !e.IsDeleted, entityType.ClrType));
            });

和

 private static LambdaExpression ConvertFilterExpression<TInterface>(
                Expression<Func<TInterface, bool>> filterExpression,
                Type entityType)
    {
        var newParam = Expression.Parameter(entityType);
        var newBody = ReplacingExpressionVisitor.Replace(filterExpression.Parameters.Single(), newParam, filterExpression.Body);

        return Expression.Lambda(newBody, newParam);
    }

Answer 6

对于 EF 核心版本 6.0，这里是一个扩展函数，它将“软删除”过滤器查询应用于所有扩展到 IDeletableEntity 接口的实体。

1. 可空版本（布尔？IsDeleted）

    public interface IDeletableEntity
    {
      public bool? IsDeleted { get; set; }
    }
      
      public static void UseSoftDelete(this ModelBuilder modelBuilder)
      {
        var softDeleteEntities = modelBuilder.Model
        .GetEntityTypes()
        .Where(t => t.ClrType.IsAssignableTo(typeof(IDeletableEntity)))
        .ToArray();
        foreach (var softDeleteEntity in softDeleteEntities)
        {
            var entityBuilder = modelBuilder.Entity(softDeleteEntity.ClrType);
            var parameter = Expression.Parameter(entityType, "e");
            var methodInfo = typeof(EF).GetMethod(nameof(EF.Property))!.MakeGenericMethod(typeof(bool?))!;
            var efPropertyCall = Expression.Call(null, methodInfo, parameter, Expression.Constant(nameof(IDeletableEntity.IsDeleted)));
            var converted = Expression.MakeBinary(ExpressionType.Coalesce, efPropertyCall, Expression.Constant(false));
            var body = Expression.MakeBinary(ExpressionType.Equal, converted, Expression.Constant(false));
            var expression = Expression.Lambda(body, parameter);
            entityBuilder.HasQueryFilter(expression);
        }
      }

2. 不可为空的版本（布尔 IsDeleted）

    public interface IDeletableEntity
    {
      public bool IsDeleted { get; set; }
    }
      
      public static void UseSoftDelete(this ModelBuilder modelBuilder)
      {
        var softDeleteEntities = modelBuilder.Model
        .GetEntityTypes()
        .Where(t => t.ClrType.IsAssignableTo(typeof(IDeletableEntity)))
        .ToArray();
        foreach (var softDeleteEntity in softDeleteEntities)
        {
            var entityBuilder = modelBuilder.Entity(softDeleteEntity.ClrType);
            var parameter = Expression.Parameter(entityType, "e");
            var methodInfo = typeof(EF).GetMethod(nameof(EF.Property))!.MakeGenericMethod(typeof(bool))!;
            var efPropertyCall = Expression.Call(null, methodInfo, parameter, Expression.Constant(nameof(IDeletableEntity.IsDeleted)));
            var body = Expression.MakeBinary(ExpressionType.Equal, efPropertyCall, Expression.Constant(false));
            var expression = Expression.Lambda(body, parameter);
            entityBuilder.HasQueryFilter(expression);
        }
      }

Answer 7

我觉得涉及Expression和ReplacingExpressionVisitor的解决方案太复杂了。 我会用一种更直接的方式写这个，使用反射。

第 1 步：将您的查询过滤器提取到它自己的方法中。

private static SetNotSoftDeletedQueryFilter<T>(ModelBuilder builder) where T : class, IDeletableEntity
{
  builder.Entity<T>().HasQueryFilter(m => EF.Property<Boolean>(m, "IsDeleted") == false);
}

第 2 步：通过反射获取上述方法的挂钩。

private static readonly MethodInfo SetNotSoftDeletedQueryFilterMethod = typeof(ApplicationDbContext)
  .GetMethod(nameof(SetNotSoftDeletedQueryFilter), BindingFlags.Static | BindingFlags.NonPublic)!;

第 3 步：调用！

builder.Model.GetEntityTypes()
  .Where(entityType => typeof(IDeletableEntity).IsAssignableFrom(entityType.ClrType))
  .ToList()
  .ForEach(entityType =>
  {
    builder.Entity(entityType.ClrType).Property<Boolean>("IsDeleted");
    //builder.Entity(entityType.ClrType).HasQueryFilter(e => EF.Property<Boolean>(e, "IsDeleted") == false);
    SetNotSoftDeletedQueryFilterMethod.MakeGenericMethod(entityType.ClrType)
      .Invoke(null, new object[] { builder });
  });

Answer 8

使用以下代码获取所有实体并过滤属性：

foreach (var entityType in modelBuilder.Model.GetEntityTypes())
        {
            if (entityType.ClrType.GetCustomAttributes(typeof(AuditableAttribute), true).Length > 0)
            {                                       
                modelBuilder.Entity(entityType.Name).Property<bool>("IsRemoved");                   
            }

            var isActiveProperty = entityType.FindProperty("IsRemoved");
            if (isActiveProperty != null && isActiveProperty.ClrType == typeof(bool))
            {
                var entityBuilder = modelBuilder.Entity(entityType.ClrType);
                var parameter = Expression.Parameter(entityType.ClrType, "e");
                var methodInfo = typeof(EF).GetMethod(nameof(EF.Property))!.MakeGenericMethod(typeof(bool))!;
                var efPropertyCall = Expression.Call(null, methodInfo, parameter, Expression.Constant("IsRemoved"));
                var body = Expression.MakeBinary(ExpressionType.Equal, efPropertyCall, Expression.Constant(false));
                var expression = Expression.Lambda(body, parameter);
                entityBuilder.HasQueryFilter(expression);
            }                
        }