如何解决对位值的IndexOutOfRangeException？ [英] How to resolve an IndexOutOfRangeException on bit value?

问题描述

我在读回从SQL表中位值，和铸造作为一个布尔值映射到一个布尔模型值。

I'm reading back a bit value from an SQL table, and casting as a boolean value to map to a boolean model value.

但是，当我读回 IsPDLChecked 位字段并初始化为假，我得到一个索引超出范围异常。

But when I read back the IsPDLChecked bit field and initialise as false, I get an index out of range exception.

我抬头异常的定义，我不知道为什么值超出范围，由于它是初始化一个假值的，即 0 。因此，这不是一个消极的范围值。

I looked up the definition of the exception and I'm not sure why the value is out of range due to it being init with a false value, ie, 0. So it's not a negative range value.

问：

为什么我收到一个 IndexOutOfRange例外虽然被读回位值转换为BOOL和初始化为假？

Why am I getting an IndexOutOfRange exception although the bit value being read back is cast to bool and init to false?

code：

示范 -

public partial class EmailContact
{
    public int ContactID { get; set; }
    public bool IsPDLChecked { get; set; }
    public string ContactDisplayName { get; set; }
    public string ContactEmailAddress { get; set; }   

}

数据读取片段 -

Data reader snippet -

                        while (dataReader.Read())
                        {
                            statusList.Add(new EmailContact(dataReader["IsPDLChecked"] as bool? ?? false,dataReader["ContactDisplayName"].ToString(), dataReader["ContactEmailAddress"].ToString()));
                        }

错误详细信息：

System.IndexOutOfRangeException was caught
  HResult=-2146233080
  Message=IsPDLChecked
  Source=System.Data
  StackTrace:
       at System.Data.ProviderBase.FieldNameLookup.GetOrdinal(String fieldName)
       at System.Data.SqlClient.SqlDataReader.GetOrdinal(String name)
       at System.Data.SqlClient.SqlDataReader.get_Item(String name)

DB模式：（我也注意到了CHARACTER_MAX_LENGTHcollumn被设置为null这个）：

DB值：（IsPDLChecked有一个值）

DB values: (IsPDLChecked has a value)

推荐答案

的<一个href=\"https://msdn.microsoft.com/en-us/library/system.data.sqlclient.sqldatareader.getordinal(v=vs.110).aspx\"相对=nofollow>文档说，在 IndexOutOfRangeException 你要当指定的名称不是有效的列名被抛出。

The documentation says that the IndexOutOfRangeException you're getting is thrown when "the name specified is not a valid column name".

你应该做的第一件事是在C＃中的比赛，以确保列名称与表中（或在查询，如果他们被重新定义）：

The first thing you should do is to make sure the columns name in C# match those in the table (or in the query if they are redefined):

SELECT ContactDisplayName, ContactEmailAddress, IsPDLChecked FROM table

或

SELECT * FROM table

将返回的列名，就可以相同的，因为它们是在表中和读者要细，因为它是现在。

will return column names that will be the same as they are in the table and your reader should be fine as it is right now.

但是，如果您的查询是这样的：

But if your query looks like this:

SELECT ContractDisplayName as Name,
       ContactEmailAddress as Email,
       IsPDLChecked as Checked
  FROM table

您将需要在C＃中读取结果是这样的：

you will need to read the result like this in C#:

dataReader["Name"]
dataReader["Email"]
dataReader["Checked"]

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