C# 如何在GroupBy中使用Include

这是我的模型的一部分：

public class Transaction
{
    public int Id { get; set; }
    public Decimal Amount { get; set; }
    public DateTime Date { get; set; }
    public string Comment { get; set; }
    public Subcategory TransactionSubcategory { get; set; }
    public Member OwnerMember { get; set; }
    public int TransactionSubcategoryId { get; set; }
    public int OwnerMemberId { get; set; }
}

public class Subcategory
{
    public Subcategory()
    {
        IsGlobal = false;
        Transactions = new List<Transaction>();
    }
    public int Id { get; set; }
    public string Name { get; set; }
    public Category OwnerCategory { get; set; }
    public List<Transaction> Transactions { get; set; }
    public bool IsGlobal { get; set; }
}

public class Category
{
    public Category()
    {
        IsGlobal = false;
    }
    public int Id { get; set; }
    public string Name { get; set; }
    public List<Subcategory> Subcategories { get; set; }
    public TransactionType TypeOfTransaction { get; set; }
    public Budget OwnerBudget { get; set; }
    public bool IsGlobal { get; set; }
}

public class Member
{
    public Member()
    {
        Transactions = new List<Transaction>();
    }
    public Budget OwnerBudget { get; set; }
    public int Id { get; set; }
    public string Name { get; set; }
    public DateTime CreatedTime { get; set; }
    public List<Transaction> Transactions { get; set; }
}

但它仍然是空的。如果我换成

        var members = transactions
            .GroupBy(t => t.OwnerMember, t => t)
            .Include(t=> t.Select(t2 => t2.TransactionSubcategory.OwnerCategory))
            .ToList();

我犯了一个错误：

EntityFramework.dll中发生“System.ArgumentException”类型的异常，但未在用户代码中处理

其他信息：包含路径表达式必须引用在类型上定义的导航属性。使用虚线路径作为参考导航属性，选择运算符作为集合导航属性

---

第一：从数据库中选择时，应包括以下导航：

from o in context.Transactions.Include("TransactionSubcategory").Include("TransactionSubcategory.OwnerCategory")
...
select o

第二：从这里删除Include

var members = transactions
            .GroupBy(t => t.OwnerMember, t => t)
            .ToList();

第三：我相信您希望按ID分组，而不是按类分组，因为按引用类型分组不会得到预期的结果。具有相同字段的所有类将生成不同的组，因为它们具有不同的引用

var members = transactions
                .GroupBy(t => t.OwnerMember.Id, t => t)
                .ToList();

---

我找到了解决办法。如果我先做ToList，然后再做GroupBy

var members = transactions
            .Include(t => t.TransactionSubcategory.OwnerCategory)
            .Include(t=> t.OwnerMember).ToList()
            .GroupBy(t => t.OwnerMember, t => t)

---

.IncludeTransactionSubcategory.IncludeTransactionSubcategory.OwnerCategory有效吗？您是否将该字段定义为外键？1不，它无效2我没有向模型添加任何属性，但我找到了解决方案

var members = transactions
            .Include(t => t.TransactionSubcategory.OwnerCategory)
            .Include(t=> t.OwnerMember).ToList()
            .GroupBy(t => t.OwnerMember, t => t)