Question

场景：我有两个表：UserProfiles和BlogArticles。博客文章在UserProfile中，所以如果我想获得特定用户的所有博客文章，我会输入类似的内容：

db.UserProfiles.SingleOrDefault(x=> x.UserName == User.Idenity.Name).BlogArticles

但是，我想使用BlogArticles表来执行此操作，也就是说，我希望获得来自同一UserProfile的BlogArticles，如下所示：

db.BlogArticles(x=> ...) // these should be from one user only.

解决方法1 一种方法是向后做，如下：

db.UserProfiles.FirstOrDefault(d => d.BlogArticles.FirstOrDefault(x=> x.Id==BlogArticles) != null);

因此，给定一个BlogArticle id，可以找到UserProfile。

但是，如何使用BlogArticle表获取来自特定用户配置文件的文章列表？

我已经尝试了

db.BlogArticles.Where(x=> Functions.GetAuthor(x.Id) == User.Identity.Name).ToList()

但是我收到以下错误：

An exception of type 'System.NotSupportedException' occurred in System.Data.Entity.dll but was not handled in user code

Additional information: LINQ to Entities does not recognize the method 'System.String      GetAuthor(Int32)' method, and this method cannot be translated into a store expression.

如何以更好的方式解决这个问题？

    [Table("UserProfile")]
public class UserProfile
{
    [Key]
    [DatabaseGeneratedAttribute(DatabaseGeneratedOption.Identity)]
    public int UserId { get; set; }
    public string UserName { get; set; }

    public string Email { get; set; }

    public string Description { get; set; }

    public DateTime Created { get; set; }

    public virtual ICollection<BlogArtilce> BlogArticles { get; set; }

    public virtual ICollection<Group> Groups { get; set; }


    //public DateTime Created = DateTime.Today;

}

    [Table("BlogArticle")]
public class BlogArticle
{
    [Key]
    [DatabaseGeneratedAttribute(DatabaseGeneratedOption.Identity)]
    public  int Id { get; set; } 
    public virtual string Name { get; set; }

    public string Description { get; set; }

    public virtual string Contents { get; set; }

    public virtual int Views { get; set; }

    public virtual string Password { get; set; }

    public virtual string Tags { get; set; }
}

public class Group
{
    [Key]
    [DatabaseGeneratedAttribute(DatabaseGeneratedOption.Identity)]
    public int Id { get; set; } // this must be an int.

    public string Name { get; set; }

    public virtual ICollection<BlogArticle> BlogArticles { get; set; }
}

Answer 1

你使这变得比它需要的复杂得多。从您的OP中您已经选择了作者，因此应该可以访问作者的ID和存储它的方法。

所以，假设BlogArticles有一个名为AuthorId的属性，你的代码可能看起来像这样：

int localAuthorId = ???; // assign from wherever you fetched it

// simpler filter:
db.BlogArticles.Where(x => x.AuthorId = localAuthorId).ToList()

显示特定用户的所有博客文章

1 个答案: