DDD Code First 迁移数据实现EF CORE的软删除，值对象迁移配置

lifeng618 2018-12-25 原文

感谢Jeffcky大佬的博客：

EntityFramework Core 2.0全局过滤（HasQueryFilter） https://www.cnblogs.com/CreateMyself/p/8491058.html

什么是值对象

没有唯一的标识，固定不变的，表示一个具体的概念，用来描述一个东西的特征，代表是什么，使用时直接添加或替换，值对象在迁移时，会以字段的形式迁移到数据库中

软删除

定义删除的接口

         public interface ISoftDelete
         {
            bool IsDeleted { get; set; }
         }

创建模型实现ISoftDelete接口

       public class UserInfo : IAggregationRoot, ISoftDelete
        {       
          public Guid Id { get; set; }
          public string UserName { get; private set; }
          public string UserPassword { get; private set; }
          public string UserPhone { get; private set; }
          public Address Address { get; private set; }
          public bool IsDeleted { get; set; }
        }
        [Owned]
        public class Address:IValueObject
        { 
          public string Province { get;private set; }
          public string City { get; private set; }
          public string County { get; private set; }
          public string AddressDetails { get; private set; }    
        }

Lamda的扩展以及Code First 迁移配置

    protected override void OnModelCreating(ModelBuilder modelBuilder)
        {          
            //设置软删除
            foreach (var entityType in modelBuilder.Model.GetEntityTypes())
            {               
                var parameter = Expression.Parameter(entityType.ClrType);
                //查询类上面是否有Owned（值对象）的特性
                var ownedModelType = parameter.Type;
                var ownedAttribute = Attribute.GetCustomAttribute(ownedModelType, typeof(OwnedAttribute));
                if (ownedAttribute == null)
                {
                    var propertyMethodInfo = typeof(EF).GetMethod("Property").MakeGenericMethod(typeof(bool));
                    var isDeletedProperty =
                        Expression.Call(propertyMethodInfo, parameter, Expression.Constant("IsDeleted"));
                    BinaryExpression compareExpression = Expression.MakeBinary(ExpressionType.Equal, isDeletedProperty,
                        Expression.Constant(false));
                    var lambda = Expression.Lambda(compareExpression, parameter);
                    modelBuilder.Entity(entityType.ClrType).HasQueryFilter(lambda);
                }      
            }
        }

在这里需要过滤掉值对象的类，在值对象的类上面声明一个特性，通过该特性过滤掉该值对象，如果该类是值对象就直接跳过，不过滤值对象EF CORE会给值对象附加一个IsDeleted的字段，EF CORE执行中会报错，提示找不到该字段
Owned是EF CORE 配置值对象的特性，可以去自定义特性，在每一个值对象上面声明，在OnModelCreating 过滤掉包含这个特性的类
最终实现的代码：

         public async Task>> GetUserList(SearchUserDto input)
         {
            Expression> where = e => e.IsDisable == false;
            if (!string.IsNullOrEmpty(input.SearchName))
            {
                where = where.And(e => e.UserName.Contains(input.SearchName));
            }
 
            if (!string.IsNullOrEmpty(input.SearchPwd))
            {
                where = where.And(e => e.UserPhone.Contains(input.SearchPwd));
            }
         
            var userList = await _userRepository.LoadEntityListAsync(where, e => e.UserName, "asc", input.PageIndex, input.Pagesize);
            var total = await _userRepository.GetEntitiesCountAsync(where);
            var userDtoList = userList.MapToList();
 
            HeaderResult> result = new HeaderResult>
            {
                IsSucceed = true,
                Result = userDtoList,
                Total = total
            };
            return result;
        }