2

我正在尝试从我的 XML 元素中获取值并使用 linq 命令将其转换为整数，以便我可以使用它做一些数学方程式。

到目前为止，这是我尝试过的方式：

private void buttonTab4Mod1Calculate_Click(object sender, EventArgs e)
        {
            var document = XDocument.Load(workingDir + @"\Level4.xml");

            var assessmentOneWeight = from d in document.Descendants("moduleTitle")
                                      where d.Value == (String)comboBoxTab4Mod8.SelectedItem
                                      select d.Parent.Element("assessmentOneWeight").Value;
            int a = 0;
            foreach (var item in assessmentOneWeight)
            {
                a = Convert.ToInt32(item);
            }
            MessageBox.Show(a.ToString());
        }

但由于某种原因，该值仍为 0。

这是我的 xml 文件：

<?xml version="1.0" encoding="utf-8" ?>
<SoftwareEngineering>
  <Module>
    <moduleCode>ECSE401</moduleCode>
    <moduleTitle>Programming Methodology</moduleTitle>
    <credits>15</credits>
    <assessmentOne>Coursework</assessmentOne>
    <assessmentOneWeight>40</assessmentOneWeight>
    <assessmentTwo>Coursework</assessmentTwo>
    <assessmentTwoWeight>40</assessmentTwoWeight>
    <assessmentThree>Test</assessmentThree>
    <assessmentThreeWeight>20</assessmentThreeWeight>
  </Module>
  <Module>
    <moduleCode>ECSC404</moduleCode>
    <moduleTitle>Computer Systems Fundamentals</moduleTitle>
    <credits>15</credits>
    <assessmentOne>Test1</assessmentOne>
    <assessmentOneWeight>30</assessmentOneWeight>
    <assessmentTwo>Test2</assessmentTwo>
    <assessmentTwoWeight>30</assessmentTwoWeight>
    <assessmentThree>Test3</assessmentThree>
    <assessmentThreeWeight>40</assessmentThreeWeight>
  </Module>
  <Module>
    <moduleCode>EBSY401</moduleCode>
    <moduleTitle>Information and Data Modelling</moduleTitle>
    <credits>15</credits>
    <assessmentOne>Test</assessmentOne>
    <assessmentOneWeight>25</assessmentOneWeight>
    <assessmentTwo>Coursework1</assessmentTwo>
    <assessmentTwoWeight>10</assessmentTwoWeight>
    <assessmentThree>Coursework2</assessmentThree>
    <assessmentThreeWeight>35</assessmentThreeWeight>
    <assessmentFour>Coursework3</assessmentFour>
    <assessmentFourWeight>30</assessmentFourWeight> 
  </Module>
  <Module>
    <moduleCode>ECSC405</moduleCode>
    <moduleTitle>Software Development Principles</moduleTitle>
    <credits>15</credits>
    <assessmentOne>Test1</assessmentOne>
    <assessmentOneWeight>30</assessmentOneWeight>
    <assessmentTwo>Coursework</assessmentTwo>
    <assessmentTwoWeight>40</assessmentTwoWeight>
    <assessmentThree>Test2</assessmentThree>
    <assessmentThreeWeight>30</assessmentThreeWeight>
  </Module>
  <Module>
    <moduleCode>ECSC407</moduleCode>
    <moduleTitle>Web Technology</moduleTitle>
    <credits>15</credits>
    <assessmentOne>Tutorials</assessmentOne>
    <assessmentOneWeight>20</assessmentOneWeight>
    <assessmentTwo>Coursework</assessmentTwo>
    <assessmentTwoWeight>20</assessmentTwoWeight>
    <assessmentThree>Exam</assessmentThree>
    <assessmentThreeWeight>60</assessmentThreeWeight>
  </Module>
  <Module>
    <moduleCode>ECSC409</moduleCode>
    <moduleTitle>Software Engineering Principles</moduleTitle>
    <credits>15</credits>
    <assessmentOne>Coursework1</assessmentOne>
    <assessmentOneWeight>40</assessmentOneWeight>
    <assessmentTwo>Coursework2</assessmentTwo>
    <assessmentTwoWeight>30</assessmentTwoWeight>
    <assessmentThree>Coursework3</assessmentThree>
    <assessmentThreeWeight>30</assessmentThreeWeight>
  </Module>
  <Module>
    <moduleCode>ECSC408</moduleCode>
    <moduleTitle>Mathematics for Computing</moduleTitle>
    <credits>15</credits>
    <assessmentOne>Coursework</assessmentOne>
    <assessmentOneWeight>50</assessmentOneWeight>
    <assessmentTwo>Exam</assessmentTwo>
    <assessmentTwoWeight>50</assessmentTwoWeight>
  </Module>
  <Module>
    <moduleCode>EBSY400</moduleCode>
    <moduleTitle>Communication and Learning Skills</moduleTitle>
    <credits>15</credits>
    <assessmentOne>Coursework</assessmentOne>
    <assessmentOneWeight>30</assessmentOneWeight>
    <assessmentTwo>Coursework</assessmentTwo>
    <assessmentTwoWeight>70</assessmentTwoWeight>
  </Module>
</SoftwareEngineering>

非常感谢一些帮助。

4

2 回答 2

4

只需投射XElement到int：

private void buttonTab4Mod1Calculate_Click(object sender, EventArgs e)
{
    var document = XDocument.Load(workingDir + @"\Level4.xml");

    string selectedItem = (string) comboBoxTab4Mod8.SelectedItem;
    var assessmentOneWeight = from d in document.Descendants("moduleTitle")
                              where (string) d == selectedItem
                              select (int) d.Parent.Element("assessmentOneWeight");
    foreach (int item in assessmentOneWeight)
    {
         MessageBox.Show(item.ToString());
    }        
}

请注意，当引用是 an 时，您也可以转换为whichint?的工作方式相同，但是如果您将 null 引用转换为您将返回一个 null 值 - 如果您不知道是否存在相应的元素，这可能会很有帮助或不。XElementint?

有很多明确的转换XElement，而且XAttribute- 它们让生活变得更轻松。

于 2012-04-15T22:05:23.647 回答
1

我很确定您的assessmentOneWeight集合不包含单个值，因为comboBoxTab4Mod8.SelectedItem在 XML 中找不到 的值。

因此你总是得到0，因为a是用 初始化的0。

顺便说一句：我强烈建议您改进代码。

迭代<Module>元素而不是<moduleTitle>元素。这更有意义，因为您需要此元素的数据（即<assessmentOneWeight>）

<assessmentOneWeight直接在 LINQ 语句中转换 >的值，如下所示：

var assessmentOneWeight =
    from d in document.Descendants("moduleTitle")
    where d.Value == (String)comboBoxTab4Mod8.SelectedItem
    select int.Parse(d.Parent.Element("assessmentOneWeight").Value);

您foreach的设计不是很好，因为它只需要在您的收藏中找到的最后一个值。如果您真的想要该值，请使用 LINQ 的强大功能并仅选择该值。

于 2012-04-15T22:05:07.320 回答