0

我正在使用以下代码从 Web 表单中收集数据：

secondContact.FirstName = txtFirstNameContact2.Text;
secondContact.LastName = txtlastNameContact2.Text;
secondContact.EmailAddress = txtEmailAddressContact2.Text;
secondContact.PhoneNumber = txtPhone1Contact2.Text + txtPhone2Contact2.Text + txtPhone3Contact2.Text;
if (!string.IsNullOrEmpty(rblContactTypeContact2.SelectedValue))
{
    secondContact.SecondaryContactTypeID = Convert.ToInt32(rblContactTypeContact2.SelectedValue);
}
secondContact.ContactPosition = 2;
secondContact.ProspectID = prospect.Id;

将代码发送到存储库以使用以下代码保存（它成功获取了前景.Id）：

if (prospect.Id != 0)
   {
    if (!string.IsNullOrEmpty(secondContact.FirstName) || !string.IsNullOrEmpty(secondContact.LastName) || !string.IsNullOrEmpty(secondContact.EmailAddress) || !string.IsNullOrEmpty(secondContact.PhoneNumber))
    {
        this.repository.SaveAltContact(prospect.Id, 2, secondContact);
    }
}

存储库尝试保存数据：

public void SaveAltContact(int prospectID, int contactPosition, SecondaryContact contact)
{
    using (var context = new CoyleHomeBuyerEntities())
    {
        SecondaryContact currentAltContact = new Model.SecondaryContact();

        currentAltContact = (from sec in context.SecondaryContact
                             where sec.ContactPosition == contactPosition
                             where sec.ProspectID == prospectID
                             select sec).FirstOrDefault();

        if (currentAltContact == null)
        {
            context.AddToSecondaryContact(currentAltContact);
        }

        currentAltContact.FirstName = contact.FirstName;
        currentAltContact.LastName = contact.LastName;
        currentAltContact.EmailAddress = contact.EmailAddress;
        currentAltContact.PhoneNumber = contact.PhoneNumber;
        currentAltContact.SecondaryContactTypeID = contact.SecondaryContactTypeID;
        currentAltContact.ProspectID = prospectID;
        currentAltContact.ContactPosition = contactPosition;

        context.SaveChanges();
    }
}

在此行之后它总是失败并出现 Null 异常：

context.AddToSecondaryContact(currentAltContact);

我很困惑，因为我希望上面的查询此时返回一个 NULL 值。 SecondaryContactID设置为主键并自动递增。

Exception Details: System.ArgumentNullException: Value cannot be null.
Parameter name: entity

有人可以指出我在尝试向数据库添加新行时为什么失败的正确方向吗？

4

2 回答 2

2

您正在添加 null 作为记录，contact而不是currentAltContact在数据库中没有记录时添加。AddToSecondaryContact 方法将具有添加新记录的联系人对象和当您想要更新记录时的 currentAltContact。

改变

if (currentAltContact == null)
{
    context.AddToSecondaryContact(currentAltContact);
}

至 

if (currentAltContact == null)
{
    context.AddToSecondaryContact(contact);
}
于 2013-01-21T06:36:34.557 回答
0

实际上，我通过简单地在顶部声明 currentAltContact 变量并仅在有空记录时实例化一个新对象来使其工作 

public void SaveAltContact(int prospectID, int contactPosition, SecondaryContact contact)
    {
        using (var context = new CoyleHomeBuyerEntities())
        {
                SecondaryContact currentAltContact;

            currentAltContact = (from sec in context.SecondaryContact
                                 where sec.ContactPosition == contactPosition
                                 where sec.ProspectID == prospectID
                                 select sec).FirstOrDefault();

            if (currentAltContact == null)
            {
                currentAltContact = new Model.SecondaryContact();
                context.AddToSecondaryContact(currentAltContact);
            }

            currentAltContact.FirstName = contact.FirstName;
            currentAltContact.LastName = contact.LastName;
            currentAltContact.EmailAddress = contact.EmailAddress;
            currentAltContact.PhoneNumber = contact.PhoneNumber;
            currentAltContact.SecondaryContactTypeID = contact.SecondaryContactTypeID;
            currentAltContact.ProspectID = prospectID;
            currentAltContact.ContactPosition = contactPosition;

            context.SaveChanges();
        }
    }
于 2013-01-21T06:52:25.817 回答