c# - 值不能为空。参数名称：元素

Question

我正在尝试从 XML 信用报告中提取数据。我需要清除某些条目的能力。

这是我用来尝试获取值列表的代码。

            var trades = from x in xmlStr.Descendants("USTrade")
                    where (int) x.Element("BalanceAmount") > 0
                      select  (int)x.Element("ScheduledPaymentAmount");

示例数据如下所示：

      <USTrade>
        <ExpandedDataDimensionsReturned code="T" description="Enhanced Trade with All 6.0 Trade Fields" />
        <CreditorId>
          <CustomerNumber>801ON00630</CustomerNumber>
          <Name>BK OF AMER</Name>
          <Industry code="ON" description="National Credit Card Cos." />
        </CreditorId>
        <DateReported format="MM/CCYY">07/2019</DateReported>
        <DateOpened format="MM/CCYY">12/2007</DateOpened>
        <AccountNumber>4509128960678</AccountNumber>
        <HighCreditAmount>0020500</HighCreditAmount>
        <BalanceAmount>0000076</BalanceAmount>
        <PortfolioType code="R" description="Revolving or Option (open-end account)" />
        <Status code="1" description="Pays Acct As Agreed" />
        <MonthsReviewed>21</MonthsReviewed>
        <AccountDesignator code="I" description="Individual" />
        <DateOfLastActivity format="MM/CCYY">07/2019</DateOfLastActivity>
        <ScheduledPaymentAmount>0000015</ScheduledPaymentAmount>
        <UpdateIndicator code="*" description="Tape" />
        <Narratives>
          <Narrative code="FE" description="Credit Card" />
          <Narrative code="AZ" description="Amount In H/C Column Is Credit Limit" />
        </Narratives>
        <ExpandedCreditorId>
          <Name>BANK OF AMERICA</Name>
        </ExpandedCreditorId>
        <ExpandedDateReported format="MM/CCYY">07/2019</ExpandedDateReported>
        <ExpandedDateOpened format="MM/CCYY">12/2007</ExpandedDateOpened>
        <ExpandedCreditLimit>000020500</ExpandedCreditLimit>
        <ExpandedBalanceAmount>000000076</ExpandedBalanceAmount>
        <ExpandedPortfolioType code="R" description="Revolving or Option (open-end account)" />
        <ExpandedStatus code="1" description="Pays Acct As Agreed" />
        <ExpandedNarratives>
          <Narrative code="FE" description="Credit Card" />
        </ExpandedNarratives>
        <ExpandedScheduledPaymentAmount>000000015</ExpandedScheduledPaymentAmount>
      </USTrade>
      <USTrade>
        <ExpandedDataDimensionsReturned code="T" description="Enhanced Trade with All 6.0 Trade Fields" />
        <CreditorId>
          <CustomerNumber>801ON00630</CustomerNumber>
          <Name>BK OF AMER</Name>
          <Industry code="ON" description="National Credit Card Cos." />
        </CreditorId>
        <DateReported format="MM/CCYY">10/2018</DateReported>
        <DateOpened format="MM/CCYY">12/2007</DateOpened>
        <AccountNumber>4509128960565</AccountNumber>
        <Status code="B" description="Lost or Stolen Card" />
        <DateOfLastActivity format="MM/CCYY">10/2018</DateOfLastActivity>
        <UpdateIndicator code="*" description="Tape" />
        <Narratives>
          <Narrative code="FE" description="Credit Card" />
        </Narratives>
        <ExpandedCreditorId>
          <Name>BANK OF AMERICA</Name>
        </ExpandedCreditorId>
        <ExpandedDateReported format="MM/CCYY">10/2018</ExpandedDateReported>
        <ExpandedDateOpened format="MM/CCYY">12/2007</ExpandedDateOpened>
        <ExpandedStatus code="B" description="Lost or Stolen Card" />
        <ExpandedNarratives>
          <Narrative code="FE" description="Credit Card" />
        </ExpandedNarratives>
      </USTrade>

我不断收到“值不能为空。参数名称：元素”错误。

当我通过数据挖掘时，我看到一些没有我正在搜索的元素的 USTrades - 这会导致问题吗？如果是这样，我该如何解释？（IE A UsTrade 没有 ScheduledPaymentAmount 元素）

谢谢

标签： c#xml

Answer 1

您可以修改查询以仅搜索具有ScheduledPaymentAmount元素的对象。例如

var trades = from x in xmlStr.Descendants("USTrade")
                    where (int) x.Element("BalanceAmount") > 0 
                    and x.Element("ScheduledPaymentAmount") != null
                    select  (int)x.Element("ScheduledPaymentAmount");