C# net内核如何在viewmodel实体框架中加载相关数据

我正在从事一个

Asp.net core 2.2

项目，在ViewModel中加载相关数据时遇到问题

首先，我有一个名为

QuestionTbl

的表：

public class Question
{
    [Key]
    public int questionID { get; set; }
    public string questionTitle { get; set; }
    public string GroupID { get; set; }
}

public class Group
{
    [Key]
    public int GroupID { get; set; }
    public string GroupName { get; set; }
}

如您所见，我在

Question

表中有一个名为

GroupID

的

string

属性，它显示了每个问题的组

例如

1 row in questionTbl
---------
questionID = 1
questionTitle = 'What is Your Name ?'
GroupID = '3,4,5'

在上面的例子中，

ID=1

的问题分为3组

（3、4和5）

和

GroupTbl

：

public class Question
{
    [Key]
    public int questionID { get; set; }
    public string questionTitle { get; set; }
    public string GroupID { get; set; }
}

public class Group
{
    [Key]
    public int GroupID { get; set; }
    public string GroupName { get; set; }
}

现在，我想展示相关组的问题列表

我有一个像这样的

ViewModel

：

public class GetQuestionViewModel
{
    public int questionID { get; set; }
    public string questionTitle { get; set; }
    public ICollection<Group> QuestionGroups { get; set; }
}

---

我想要一个包含问题和每个问题组的列表。但是

QuestionGroups

在我的查询中返回null。我也阅读了链接，但它对我没有帮助。

规范化您的表格，如下所示：

问题：

public class Question
{
    [Key]
    public int questionID { get; set; }
    public string questionTitle { get; set; }

    public int GroupID { get; set; }
    [ForeignKey("Group_ID")]
    public virtual Group Group { get; set; }
}

public class Group
{
    [Key]
    public int GroupID { get; set; }
    public string GroupName { get; set; }

    public virtual List<Question> questions { get; set; }
}

组：

public class Question
{
    [Key]
    public int questionID { get; set; }
    public string questionTitle { get; set; }

    public int GroupID { get; set; }
    [ForeignKey("Group_ID")]
    public virtual Group Group { get; set; }
}

public class Group
{
    [Key]
    public int GroupID { get; set; }
    public string GroupName { get; set; }

    public virtual List<Question> questions { get; set; }
}

---

按照以下步骤规范化表：

问题：

public class Question
{
    [Key]
    public int questionID { get; set; }
    public string questionTitle { get; set; }

    public int GroupID { get; set; }
    [ForeignKey("Group_ID")]
    public virtual Group Group { get; set; }
}

public class Group
{
    [Key]
    public int GroupID { get; set; }
    public string GroupName { get; set; }

    public virtual List<Question> questions { get; set; }
}

组：

public class Question
{
    [Key]
    public int questionID { get; set; }
    public string questionTitle { get; set; }

    public int GroupID { get; set; }
    [ForeignKey("Group_ID")]
    public virtual Group Group { get; set; }
}

public class Group
{
    [Key]
    public int GroupID { get; set; }
    public string GroupName { get; set; }

    public virtual List<Question> questions { get; set; }
}

---

您不能直接将

Include

用于viewModel。我建议您可以将其用于提问和分组模型

型号：

public class Question
{
    [Key]
    public int questionID { get; set; }
    public string questionTitle { get; set; }

    public List<QuestionGroup> QuestionGroups { get; set; }
    //public List<Group> Groups { get; set; }
    //public string GroupID { get; set; }
}
public class Group
{
    [Key]
    public int GroupID { get; set; }
    public string GroupName { get; set; }

    public List<QuestionGroup> QuestionGroups { get; set; }
}

public class QuestionGroup
{
    public int QuestionId { get; set; }
    public Question Question { get; set; }

    public int GroupId { get; set; }
    public Group Group { get; set; }
}

public class GetQuestionViewModel
{
    public int questionID { get; set; }
    public string questionTitle { get; set; }
    public ICollection<Group> QuestionGroups { get; set; }
}

---

您不能直接将

Include

用于viewModel。我建议您可以将其用于提问和分组模型

型号：

public class Question
{
    [Key]
    public int questionID { get; set; }
    public string questionTitle { get; set; }

    public List<QuestionGroup> QuestionGroups { get; set; }
    //public List<Group> Groups { get; set; }
    //public string GroupID { get; set; }
}
public class Group
{
    [Key]
    public int GroupID { get; set; }
    public string GroupName { get; set; }

    public List<QuestionGroup> QuestionGroups { get; set; }
}

public class QuestionGroup
{
    public int QuestionId { get; set; }
    public Question Question { get; set; }

    public int GroupId { get; set; }
    public Group Group { get; set; }
}

public class GetQuestionViewModel
{
    public int questionID { get; set; }
    public string questionTitle { get; set; }
    public ICollection<Group> QuestionGroups { get; set; }
}

---

您的表未规范化，因此您的

Include

将无法在EF Core中工作。我强烈建议您更改您的型号，使其符合要求。@chakeda谢谢。我想我应该改变表的结构。表的可能副本没有规范化，因此您的

Include

在EF-Core中无法工作。我强烈建议您更改您的型号，使其符合要求。@chakeda谢谢。我想我应该改变表的结构，可能是