Question

我有一个xml填充的组合框。如果builderemail（使用streamreader解析文本）等于xml文件中找到的任何一个值，组合框将选择索引。我该如何选择呢？

    if (line.StartsWith("Builder_Email:"))
                        {   
                            bool IsNodeExists = false;
                            string[] fields = line.Split('\t');
                            string builderemail = fields[3];
                            XmlDocument emailparse = new XmlDocument();
                            emailparse.Load(@"C:\GUI\buildermanageremail.xml");
                            XmlNodeList emailnode = emailparse.GetElementsByTagName("value");
                            if (string.IsNullOrEmpty(builderemail))
                                comboBox1.SelectedIndex = -1;
                            else
                            foreach (XmlNode node in emailnode)
                            {
                                if (builderemail == node.InnerText)
                                {
                                // how do i get the combobox selection right?
                                // need some code here
                                    IsNodeExists = true;
                                    break;
                                }
                            }
                            if(!IsNodeExists)
                            {
                                //create main node
                                XmlNode abc = emailparse.CreateNode(XmlNodeType.Element, "builder", null);

                                //create the first child node
                                XmlNode value = emailparse.CreateElement("value");
                                //set the value
                                value.InnerText = builderemail;

                                // add childes to father
                                //node.AppendChild(id);
                                abc.AppendChild(value);

                                // find the node we want to add the new node to
                                XmlNodeList l = emailparse.GetElementsByTagName("builderemail");
                                // append the new node
                                l[0].AppendChild(abc);
                                // save the file
                                emailparse.Save(@"C:\GUI\buildermanageremail.xml");

                                //then we populate the new updated xml file into the drop down list:
                                PopulateDDLFromXMLFile();   

                                int count = emailparse.SelectNodes("email/builderemail/builder").Count;
                                count--;
                                comboBox1.SelectedIndex = count;
                            }
                         }

要看的地方就在这里：

foreach (XmlNode node in emailnode)
                            {
                                if (builderemail == node.InnerText)
                                {
                                // how do i get the combobox selection right?
                                // need some code here
                                    IsNodeExists = true;
                                    break;
                                }
                            }

Answer 1

我相信这段代码可以完成您希望代码执行的所有操作。这段代码当然不是完美的，甚至可能都不起作用，但是如果你把它与你的代码进行比较，你应该会发现它可能会使用你在代码中没有遵循的六种做法，而且可能应该这样做。如果你删除所有断言，你会发现它只有10行代码（不包括重构方法）。

if (line.StartsWith("Builder_email:"))
{
   Debug.Assert(
      line.Where(x => x == '\t').Count() > 2), 
      "Can't parse input line.");
   string builderEmail = line.Split('\t')[3];
   Debug.Assert(
       builderEmail != null && builderEmail == builderEmail.Trim(),
      "Input data is bad.");
   string filename = @"C:\GUI\buildermanageremail.xml"
   Debug.Assert(
      File.Exists(filename),
      "Expected XML file does not exist.");
   XmlDocument emailXml = new XmlDocument();
   emailXml.Load(filename);

   // In your real application, you know the name of the document element, so you
   // should replace * with it in the XPath below.
   string xpath = string.Format(
      "/*/builderemail/builder/value[.='{0}']", 
      builderEmail);
   if (emailXml.SelectSingleNode(xpath) == null)
   {
      CreateBuilderEmailElement(emailXml, builderEmail);
      emailXml.Save(filename);
      // I've changed the name of this method, which is problematic for several
      // reasons - not least of which is that in my world, at least, "DDL" means
      // "Data Definition Language."
      //
      // This also assumes that you've created an overload of the method that
      // takes an XmlDocument argument.
      PopulateEmailComboBox(emailXml);
   }
   // I'm assuming that the builderEmail is the actual text value stored in the
   // combo box items, in which case all you need to do is find the item with that
   // value and set SelectedItem, which will automatically set SelectedIndex.  Also,
   // if the value isn't found, setting SelectedItem to null automatically sets
   // SelectedIndex to -1.
   builderEmailComboBox.SelectedItem = builderEmailComboBox.Items
      .Where(x => x.ToString() == builderEmail)
      .FirstOrNull();
}

以下是创建builderemail元素的方法 - 顺便说一句，如果您对此有任何发言权，则应将其命名为builderEmail：

// this is refactored out as its own function, and made internal so that you
// can unit test it.
internal void CreateBuilderEmailElement(XmlDocument emailXml, string builderEmail)
{
      XmlElement builder = emailXml.CreateNode("builder");
      XmlElement value = emailXml.CreateNode("value");
      builder.AppendChild(valueElm);
      value.InnerText = builderEmail;
      // again, you know the name of the document element in your application,
      // so replace the * below with it.
      Debug.Assert(
         emailXml.SelectSingleNode("/*/builderemail") != null,
         "No builderemail element found under the document element.");
      emailXml.SelectSingleNode("/*/builderemail").AppendChild(builder);
}

另外，您的XML在value下是否有单独的builderEmail元素，而不是builderEmail只包含该值？

我如何选择节点的索引？

1 个答案: