实体框架在与ForeignKey链接的列表中的字符串条件。

Question

我正试图开发一个可过滤的主题列表。有2个用外键连接的表，我应该写一个LINQ查询，通过客户端发送的 "SpecId == 2 AND ValueBit == true "这样的字符串过滤来搜索主题。我应该写一个LINQ查询，通过客户端发送的字符串过滤器来搜索主题，比如 "SpecId == 2 AND ValueBit == true"。我在我的服务项目中使用了存储库模式，并试图这样做，但我无法实现我想要的过滤器。

1. x.TopicSpecs.Where(condition)部分不能工作，因为条件是一个字符串。x.TopicSpecs.Where(y=> y.SpecId == 2 && y.ValueBit == true)能用，应该是动态编码的。
2. 发送查询到topicRepository和topicSpecRepository哪个正确？

我花了一整天的时间，都没能解决这个查询。请你帮帮我，好吗？

我的查询

Topics = await topicRepository.GetAllWithStringOrder(x => new TopicModel
            {
                CreatedDate = x.CreatedDate,
                Subtitle = x.Subtitle,
                Title = x.Title,
                UpdatedDate = x.UpdatedDate,
                Users = x.User.UserProfiles.Select(y => new UserProfileModel
                {
                    Nickname = y.Nickname
                }).ToList(),
                TopicId = x.TopicId,
                UserId = x.UserId,
                TopicCommentCount = x.TopicComments.Count,
                TopicSpecs = x.TopicSpecs.Where(y => y.Spec.ShowInTopic).Select(y => new TopicSpecModel
                {
                    ValueBit = y.ValueBit,
                    ValueDate = y.ValueDate,
                    ValueNumber = y.ValueNumber,
                    ValueString = y.ValueString,
                    Spec = new SpecModel
                    {
                        Name = y.Spec.Name,
                        SpecId = y.Spec.SpecId,
                        Color = y.Spec.Color
                    }
                }).ToList()
            }, x => x.IsActive && !x.IsDeleted && x.IsLatest && x.TopicSpecs.Where(condition).Count() > 0, model.ItemsPerPage.Value, model.PageNumber.Value, model.SortBy, !model.Reverse)

GetAllWithStringOrder

public virtual async Task<List<TReturn>> GetAllWithStringOrder<TReturn>(Expression<Func<TEntity, TReturn>> selectExp, Expression<Func<TEntity, bool>> whereExp, int itemsPerPage, int pageNumber, string orderBy, bool isDescending, params Expression<Func<TEntity, object>>[] includeExps)
    {
        var query = DbSet.Where(whereExp);
        if (!string.IsNullOrEmpty(orderBy))
            query = query.OrderBy(orderBy);
        if (includeExps != null)
            query = includeExps.Aggregate(query, (current, exp) => current.Include(exp));
        query = query.OrderBy(orderBy, isDescending).Skip<TEntity>((pageNumber - 1) * itemsPerPage).Take<TEntity>(itemsPerPage);
        return await query.Select(selectExp).ToListAsync();
    }

主题表

public partial class Topic
{
    [System.Diagnostics.CodeAnalysis.SuppressMessage("Microsoft.Usage", "CA2214:DoNotCallOverridableMethodsInConstructors")]
    public Topic()
    {
        this.TopicComments = new HashSet<TopicComment>();
        this.TopicContents = new HashSet<TopicContent>();
        this.TopicSpecs = new HashSet<TopicSpec>();
    }

    public int TopicId { get; set; }
    public string Title { get; set; }
    public string Subtitle { get; set; }
    public int UserId { get; set; }
    public System.DateTimeOffset CreatedDate { get; set; }
    public Nullable<System.DateTimeOffset> UpdatedDate { get; set; }
    public bool IsDeleted { get; set; }
    public bool IsLatest { get; set; }
    public bool IsActive { get; set; }

    [System.Diagnostics.CodeAnalysis.SuppressMessage("Microsoft.Usage", "CA2227:CollectionPropertiesShouldBeReadOnly")]
    public virtual ICollection<TopicComment> TopicComments { get; set; }
    [System.Diagnostics.CodeAnalysis.SuppressMessage("Microsoft.Usage", "CA2227:CollectionPropertiesShouldBeReadOnly")]
    public virtual ICollection<TopicContent> TopicContents { get; set; }
    [System.Diagnostics.CodeAnalysis.SuppressMessage("Microsoft.Usage", "CA2227:CollectionPropertiesShouldBeReadOnly")]
    public virtual ICollection<TopicSpec> TopicSpecs { get; set; }
    public virtual User User { get; set; }
}

主题规格表

public partial class TopicSpec
{
    public int TopicSpecId { get; set; }
    public int TopicId { get; set; }
    public int SpecId { get; set; }
    public string ValueString { get; set; }
    public Nullable<bool> ValueBit { get; set; }
    public Nullable<System.DateTimeOffset> ValueDate { get; set; }
    public Nullable<int> ValueNumber { get; set; }
    public bool IsActive { get; set; }

    public virtual Spec Spec { get; set; }
    public virtual Topic Topic { get; set; }
}

规格表

public partial class Spec
{
    [System.Diagnostics.CodeAnalysis.SuppressMessage("Microsoft.Usage", "CA2214:DoNotCallOverridableMethodsInConstructors")]
    public Spec()
    {
        this.TopicSpecs = new HashSet<TopicSpec>();
    }

    public int SpecId { get; set; }
    public int SpecTypeId { get; set; }
    public string Name { get; set; }
    public bool IsActive { get; set; }
    public bool ShowInTopic { get; set; }
    public string Color { get; set; }

    public virtual SpecType SpecType { get; set; }
    [System.Diagnostics.CodeAnalysis.SuppressMessage("Microsoft.Usage", "CA2227:CollectionPropertiesShouldBeReadOnly")]
    public virtual ICollection<TopicSpec> TopicSpecs { get; set; }
}

Answer 1

你在某个地方有一个Model类，这个查询是从该查询的最后一行中提取属性来运行的。

.....  model.ItemsPerPage.Value, model.PageNumber.Value, ....

如果能把这个类也公布出来可能会有帮助 尽管这已经有很多代码需要筛选了。

也就是说，问题#1的最简单的解决方案可能是在该类中添加一些属性。model 类，并在 Where 子句。

... x.TopicSpecs.Where(y=> y.SpecId == model.SpecIdValue && y.ValueBit == model.ValueBitFlag)....

在这个例子中，新的模型属性是 model.SpecIdValue 作为 int 和 model.ValueBitFlag 作为 bool.

我想你有那个电话 Topics = await topicRepository.GetAllWithStringOrder... 的内部，所以你可以设置我上面提到的模型属性，然后再次调用那个方法以获得更新的响应。

对于问题#2，如果你正在寻找一个类型为 Topic 作为查询的返回，你应该使用topicRepository。