Question

我有一对多的关系，我希望在大致相同的时间存储一个和多个关系。我松散地遵循教程Apple docs。

重要的部分是我的交易（很多）和账户（一个）模型：

public class Account
{
    public int ID { get; set; }

    public string Name { get; set; }

    public virtual ICollection<Transaction> Transactions { get; set; }
}


public class Transaction
{
    public int ID { get; set; }

    public decimal Amount { get; set; }
    public string Description { get; set; }
    public string Note { get; set; }

    public virtual Account Account { get; set; }
}


public class AccountContext : DbContext
{
    public AccountContext(DbContextOptions<AccountContext> options) : base(options)
    {
    }
    public DbSet<Transaction> Transactions { get; set; }
}

在我的初始化方法中：

public static void Initialize(AccountContext accountContext){

    Account account = new Account { Name = "Checking" };
    Transaction transaction = new Transaction { Amount = 120, Description = "Paycheck", Note = "First tranaction test" };
    var test = account.Transactions; //To ensure it's not the access that's throwing the error
    account.Transactions.Add(transaction); // <- right here
    //...
}

问题：最后一行抛出＆＃34;对象引用未设置为对象的实例＆＃34;例外。

我的表正在Server Explorer中创建并且看起来正确。我试过放桌子。在我尝试的几个变体中，我尝试将帐户传递给事务构造函数：

Transaction transaction = new Transaction { Account = account, Amount = 120, Description = "Paycheck", Note = "First tranaction test" };

哪个没有帮助。

构造Entity Framework初始化数据时的对象引用错误

0 个答案: