我在SQL Server数据库表中有记录，需要将其传输到付款处理API。仅将Transmitted = 0的表记录发送到API。我发现this question可以帮助我理解手头的错误。
我想将数据库表中的记录读取到C＃类中，解析为JSON，然后通过API调用发送。我尝试使用Entity Framework Core，但是在调用存储过程并将结果添加到模型类中时收到Null Reference异常，如下所示：
public async Task<IEnumerator<Onboarding>> GetOnboardingList()
{
try
{
using (var context = new SOBOContext())
{
var ob = await context.Onboarding
//.Where(o => o.Transmitted == false)
.FromSql("Execute GetUnsentOnboardingRecords_sp")
.ToListAsync();
Console.WriteLine(ob.ToArray());
}
}
catch (Exception ex)
{
Console.WriteLine(ex.Message);
}
return new OnboardingList().GetEnumerator();
}
当尝试使用Entity Framework Core时，我创建了OnboardingList类，如下所示：
public class OnboardingList : IEnumerable<Onboarding>
{
private readonly List<Onboarding> _onboarding;
public IEnumerator<Onboarding> GetEnumerator()
{
return _onboarding?.GetEnumerator();
}
IEnumerator IEnumerable.GetEnumerator()
{
return _onboarding.GetEnumerator();
}
}
然后我恢复为SqlDataReader，该方法调用存储过程。该方法的部分内容如下：
var listOnboardingModel = new List<Onboarding>();
try
{
using (SqlConnection connection = new SqlConnection(builder.ConnectionString))
{
SqlCommand cmd = new SqlCommand("GetUnsentOnboardingRecords_sp", connection)
{
CommandType = CommandType.StoredProcedure
};
connection.Open();
using (var reader = cmd.ExecuteReader())
{
while (reader.Read())
{
listOnboardingModel.Add(new Onboarding
{
OnboardingId = reader[1] as int? ?? 0,
UserId = reader[2] as int?,
UserName = reader[3].ToString(),
FirstName = reader[4].ToString(),
MiddleInitial = reader[5].ToString(),
Lastname = reader[6].ToString(),
DateOfBirth = reader[7].ToString(),
Ssn = reader[8].ToString(),
Email = reader[9].ToString(),
Address1Line1 = reader[10].ToString(),
Address1Line2 = reader[11].ToString(),
Address1ApartmentNumber = reader[12].ToString(),
Address1City = reader[13].ToString(),
Address1State = reader[14].ToString(),
Address1ZipCode = reader[15].ToString(),
Address1Country = reader[16].ToString(),
DayPhone = reader[17].ToString(),
EveningPhone = reader[18].ToString(),
PhonePin = reader[19].ToString(),
MerchantSourceIp = reader[20].ToString(),
ThreatMetrixPolicy = reader[21].ToString(),
SessionId = reader[22].ToString(),
BankAccount1CountryCode = reader[23].ToString(),
BankAccount1Name = reader[24].ToString(),
BankAccount1Description = reader[25].ToString(),
BankAccount1Number = reader[26].ToString(),
BankAccount1OwnershipType = reader[27].ToString(),
BankAccount1Type = reader[28].ToString(),
BankAccount1BankName = reader[29].ToString(),
BankAccount1RoutingNumber = reader[30].ToString(),
BankAccount2CountryCode = reader[31].ToString(),
BankAccount2Name = reader[32].ToString(),
BankAccount2Number = reader[33].ToString(),
BankAccount2OwnershipType = reader[34].ToString(),
BankAccount2Type = reader[35].ToString(),
BankAccount2BankName = reader[36].ToString(),
BankAccount2Description = reader[37].ToString(),
BankAccount2RoutingNumber = reader[38].ToString(),
AuthSginerFirstName = reader[39].ToString(),
AuthSignerLastName = reader[40].ToString(),
AuthSignerTitle = reader[41].ToString(),
AverageTicket = reader[42] as int? ?? 0,
BusinessLegalName = reader[43].ToString(),
BusinessApartmentNumber = reader[44].ToString(),
BusinessAddressLine1 = reader[45].ToString(),
BusinessAddressLine2 = reader[46].ToString(),
BusinessCity = reader[47].ToString(),
BusinessState = reader[48].ToString(),
BusinessZipCode = reader[49].ToString(),
BusinessCountry = reader[50].ToString(),
BusinessDescription = reader[51].ToString(),
DoingBusinessAs = reader[52].ToString(),
Ein = reader[53].ToString(),
HighestTicket = reader[54] as int? ?? 0,
MerchantCategoryCode = reader[55].ToString(),
MonthlyBankCardVolume = reader[56] as int? ?? 0,
OwnerFirstName = reader[57].ToString(),
OwnerLastName = reader[58].ToString(),
OwnerSsn = reader[59].ToString(),
OwnerDob = reader[60].ToString(),
OwnerApartmentNumber = reader[61].ToString(),
OwnerAddress = reader[62].ToString(),
OwnerAddress2 = reader[63].ToString(),
OwnerCity = reader[64].ToString(),
OwnerRegion = reader[65].ToString(),
OwnerZipCode = reader[66].ToString(),
OwnerCountry = reader[67].ToString(),
OwnerTitle = reader[68].ToString(),
OwnerPercentage = reader[69].ToString(),
BusinessUrl = reader[70].ToString(),
CreditCardNumber = reader[71].ToString(),
ExpirationDate = reader[72].ToString(),
NameOnCard = reader[73].ToString(),
PaymentMethodId = reader[74].ToString(),
PaymentBankAccountNumber = reader[75].ToString(),
PaymentBankRoutingNumber = reader[76].ToString(),
PaymentBankAccountType = reader[77].ToString(),
Transmitted = reader[78] as bool?,
TransmitDate = reader[79].ToString(),
InternationalId = reader[80].ToString(),
DriversLicenseVersion = reader[81].ToString(),
DocumentType = reader[82].ToString(),
DocumentExpDate = reader[83].ToString(),
DocumentIssuingState = reader[84].ToString(),
MedicareReferenceNumber = reader[85].ToString(),
MedicareCardColor = reader[86].ToString(),
PaymentBankAccountName = reader[87].ToString(),
PaymentBankAccountDescription = reader[88].ToString(),
PaymentBankCountryCode = reader[89].ToString(),
PaymentBankName = reader[90].ToString(),
PaymentBankOwnershipType = reader[91].ToString()
});
}
}
connection.Close();
}
Console.WriteLine(listOnboardingModel);
}
catch (Exception ex)
{
Console.WriteLine(ex.Message);
}
return listOnboardingModel;
运行控制台应用程序时，收到错误Exception thrown: 'System.IndexOutOfRangeException' in System.Data.SqlClient.dll
Index was outside the bounds of the array.
如何防止上述超出范围的异常，并确保包括数据库表中的所有合格记录以进行传输？
答案 0 :(得分：3)
您似乎有两个不同的问题：
.ToString()为空值，这将导致空引用异常。 检查DBNull.Value，否则将出现第一点。
我的假设是，您从1开始，而索引从零开始。因此，第一列将从零开始而不是一个。
您应该为D SqlDataReader查找Dapper或某些内置实用程序，以利用更简洁的代码调用来构建对象。 Dapper只需执行以下操作即可压缩代码：
IEnumerable<Sample> GetSamples() => dbConnection.Query<Sample>(...);
只要列名与属性名匹配，它就会填充。根据提供的实体，它看起来非常简单，但请查阅文档。
另外，您应该像这样将命令包装在using语句中，这样就不会有人意外地在连接块中间调用command.Dispose()：
using(var connection = new SqlConnection(...))
using(var command = new SqlCommand(..., ...))
{
connection.Open();
...
using(var reader = command.ExecuteReader())
while(reader.Read())
{
}
}