Question

请看下面的代码示例。

它的作用：

迭代一大堆客户。如果它已经知道客户，它将检索该客户的现有数据库对象（这是问题所在的部分）。否则，它会创建一个新对象（这很好）。
社会安全号码匹配（CPR）的所有贷款将被添加到新客户或现有客户。

问题：它适用于新客户对象，但是当我检索现有客户对象时，贷款在保存时失去与客户的关系（CustomerID = null）。它们仍然保存在数据库中。

有什么想法吗？

protected void BuildCustomerData()
{
    Console.WriteLine("  Starting the customer build.");

    var counter = 0;
    var recycleCount = 100;
    var reportingCount = 100;

    var sTime = DateTime.Now;

    var q = from c in db.IntermediaryRkos
            select c.CPR;

    var distincts = q.Distinct().ToArray();
    var numbersToProcess = distincts.Count();

    Console.WriteLine("  Identified " + numbersToProcess + " customers. " + (DateTime.Now - sTime).TotalSeconds);

    foreach (var item in distincts)
    {
        var loans = from c in db.IntermediaryRkos
                    where c.CPR == item
                    select c;

        var existing = db.Customers.Where(x => x.CPR == item).FirstOrDefault();

        if (existing != null)
        {
            this.GenerateLoanListFor(existing, loans);
            db.Entry(existing).State = System.Data.EntityState.Modified;
        }
        else
        {
            var customer = new Customer
            {
                CPR = item,
            };

            this.GenerateLoanListFor(customer, loans);
            db.Customers.Add(customer);
            db.Entry(customer).State = System.Data.EntityState.Added;
        }

        counter++;

        if (counter % recycleCount == 0)
        {
            this.SaveAndRecycleContext();
        }

        if (counter % reportingCount == 0)
        {
            Console.WriteLine("    Processed " + counter + " customers of " + numbersToProcess + ".");
        }
    }

    db.SaveChanges();
}

protected void GenerateLoanListFor(Customer customer, IQueryable<IntermediaryRko> loans)
{
    customer.Loans = new List<Loan>();

    foreach (var item in loans.Where(x => x.DebtPrefix == "SomeCategory").ToList())
    {
        var transformed = StudentLoanMap.CreateFrom(item);

        customer.Loans.Add(transformed);

        db.Entry(transformed).State = System.Data.EntityState.Added;
    }
}

编辑1：

正如所指出的，我手动设置状态。这是由于RecycleContext调用，它是为实现最大数据库事务性能而实现的：

protected void SaveAndRecycleContext()
{
    db.SaveChanges();
    db.Dispose();
    db = new SolutionDatabase();
    db.Configuration.AutoDetectChangesEnabled = false;
    db.Configuration.ValidateOnSaveEnabled = false;
}

Answer 1

现有贷款与否，当您致电

时，您将消灭客户。贷款房产

customer.Loans = new List<Loan>();

收藏属性未在保存时正确添加到父级

1 个答案: