Question

我在数据库中有一些表，它们将被连接到一个Log表中。

这是一张桌子，然后，我展示了Log张桌子

用户实体：

public class User : BaseEntity
{
    public User()
    {
        Beneficiaries = new HashSet<Beneficiary>();
        Applicants = new HashSet<Applicant>();
        UserItemCategories = new HashSet<UserItemCategory>();
        UserPropertyCategories = new HashSet<UserPropertyCategory>();
        Payments = new HashSet<Payment>();
    }

    [Required]
    public Role Role { get; set; }

    [Required]
    public string FirstName { get; set; }

    [Required]
    public string LastName { get; set; }

    [Required]
    public string Mobile { get; set; }

    [Required]
    public string Username { get; set; }

    [Required]
    public string Phone { get; set; }

    [Required]
    public string Address { get; set; }

    [Required]
    public string Password { get; set; }

    public double FixedSalary { get; set; }
    public DateTime DateOfPay { get; set; }
    public virtual ICollection<Beneficiary> Beneficiaries { get; set; }
    public virtual ICollection<Applicant> Applicants { get; set; }
    public virtual ICollection<UserItemCategory> UserItemCategories { get; set; }
    public virtual ICollection<UserPropertyCategory> UserPropertyCategories { get; set; }
    public virtual ICollection<Payment> Payments { get; set; }
}

BaseEntity 类：

public abstract class BaseEntity
{
    public string Id { get; set; }

    public DateTime DateTime { get; set; }
}

日志实体：

public class Log : BaseEntity
{
    public TrackTypeEnum Type { get; set; }

    [Required]
    public string CreatorId { get; set; }

    [Required]
    public string EntityId { get; set; }
}

在Log表中，我想将entityId加入User表的ID中我写了一个代码来处理这个问题：

public static IQueryable<TEntity> Filtered<TEntity>(this IQueryable<TEntity> entities, IQueryable<Log> logDbSet) where TEntity : BaseEntity
{
    var entitiesWithAttachedLogs = entities
        .GroupJoin(logDbSet, entity => entity.Id, log => log.EntityId, (entity, logs) => new
        {
            Entity = entity,
            Logs = logs
        });

    var groupedEntities = entitiesWithAttachedLogs.GroupBy(key => key.Entity.Id, value => new
    {
        value.Entity,
        Logs = value.Logs.DefaultIfEmpty()
    });

    var shrinkGroup = groupedEntities.SelectMany(group => group, (group, item) => new
    {
        TrackedEntity = item
    });

    var condition = shrinkGroup.Where(x =>
        (x.TrackedEntity.Logs == null || !x.TrackedEntity.Logs.Any())
        || (x.TrackedEntity.Logs.Any() && x.TrackedEntity.Logs.OrderBy(c => c.DateTime).FirstOrDefault().Type != TrackTypeEnum.Delete));
    var catchEntity = condition.Select(x => x.TrackedEntity.Entity);

    return catchEntity;
}

某些行可能没有任何日志状态。

我将获得“未删除”用户：

var models = _users.Filtered(_logs);
var foundUser = await (from user in models
                       where user.Id == currentUser.Id
                       where user.Username == currentUser.Username
                       where user.Mobile == currentUser.Mobile
                       where user.Role == currentUser.Role
                       where user.Password == currentUser.EncryptedPassword
                       where user.FirstName == currentUser.FirstName
                       where user.LastName == currentUser.LastName
                       where user.Phone == currentUser.Phone
                       select user).FirstOrDefaultAsync().ConfigureAwait(false);
return foundUser != null;

但是，当我想获取不被删除的用户（基于Log的{{1}}属性）时，它将返回此错误：

Type

请帮助我解决该问题，并根据InvalidCastException: Unable to cast object of type 'DefaultIfEmptyAsyncIterator`1[RealEstate.Domain.Tables.Log]' to type 'System.Collections.Generic.IEnumerable`1[RealEstate.Domain.Tables.Log]'.状态获取未删除的特定行。

谢谢。

LinQ的GroupJoin两个表的一些问题

0 个答案: