linq - 选择所有相关对象

Question

我有一个 linq 查询，我试图返回与所有其他 WebObjects 相关的所有 MlaArticles 但我收到错误:The LINQ to Entities 不支持指定的类型成员“RelatedWebObjectIds”。仅支持初始化程序、实体成员和实体导航属性。

这是模型...

public abstract class WebObject : IValidatableObject
{
    public WebObject()
    {
        this.Id = Guid.NewGuid();
        RelatedTags = new List<Tag>();
        RelatedWebObjects = new List<WebObject>();
    }

    [Key, DatabaseGenerated(DatabaseGeneratedOption.None)]
    public Guid Id { get; set; }
    public virtual ICollection<WebObject> RelatedWebObjects { get; set; }
    public IList<Guid> RelatedWebObjectIds { get; set; }
}

感谢您的帮助...

List<MlaArticle> assignedWebObjects = (from e in db.MlaArticles
                                       where
                                           (from w in db.WebObjects
                                            from r in w.RelatedWebObjectIds
                                            where w.Id == id
                                            select r).Contains(e.Id)
                                       select e).OrderBy(x => x.Title).ToList();

新查询。产生不同的错误:WebObject 不包含“包含”的定义和最佳扩展方法重载...有一些无效参数。

List<MlaArticle> assignedWebObjects = (from e in db.MlaArticles
                                       where
                                           (from w in db.WebObjects
                                            from r in w.RelatedWebObjects
                                            where w.Id == id
                                            select r.RelatedWebObjectIds).Contains(e.Id)
                                       select e).OrderBy(x => x.Title).ToList();

Answer 1

您的 MlaArticle 实体中是否有 RelatedWebObjects 导航属性？如果有，您可以改为这样做:

List<MlaArticle> assignedWebObjects = (from e in db.MlaArticles
                                       where
                                           (from w in db.WebObjects
                                            from r in w.RelatedWebObjects
                                            where w.Id == id
                                            select r.Id).Contains(e.Id)
                                       select e).OrderBy(x => x.Title).ToList();