读取空值并从 XML 文件 C# 获胜返回空值
本文关键字:空值 获胜 返回 文件 XML 读取 | 更新日期: 2023-09-27 18:34:08
<?xml version="1.0" encoding="utf-8"?>
<configuration version="45.2012.4.23" xmlns="http://www.example.com/">
<description>example.com</description>
<reading />
<connection>
<sourceId>452342341</sourceId>
<organization/>
<field>*</field>
</connection>
<source>
<sourceId>452342341</sourceId>
<connectionContext>
<id />
<name>testing</name>
<description />
<contextType>Section</contextType>
<organization/>
<field>Demo Field</field>
<section>testing</section>
<subSection />
</connectionContext>
<Mode>Section</Mode>
<activity>bell Testing</activity>
</source>
</configuration>
我想读取此 xml 并以窗口窗体textboxes
显示数据。
当我在列表框中选择 xml 文件时,我想从connection
标签中读取第一组数据,从connectionContext
标签中读取第二组数据,在文本框中显示值。
当存在空值时,以下代码不起作用的问题???
private void DisplayFile(string path)
{
var doc = XDocument.Load(path);
var ns = doc.Root.GetDefaultNamespace();
var conn = doc.Root.Element(ns + "connection");
textBox1.Text = conn.Element(ns + "sourceId").Value;
textBox3.Text = conn.Element(ns + "description").Value;
textBox4.Text = conn.Element(ns + "uri").Value;
textBox5.Text = conn.Element(ns + "username").Value;
var conn1 = doc.Root.Element(ns + "connectionContext");
textBox7.Text = conn1.Element(ns + "field").Value;
textBox8.Text = conn1.Element(ns + "bellName").Value;
textBox9.Text = conn1.Element(ns + "id").Value;
textBox10.Text = conn1.Element(ns + "bellboreName").Value;
}
此字段Object reference not set to an instance of an object. Object reference not set to an instance of an object.
错误消息(ns + "field").Value;
>connectionContext
位于文档根目录下source
而不是文档根目录下,因此您需要更改以下内容:
var conn1 = doc.Root.Element(ns + "connectionContext");
对此:
var conn1 = doc.Root.Element(ns + "source").Element(ns + "connectionContext");
或者,在架构中允许更大的灵活性:
var conn1 = doc.Descendants(ns + "connectionContext").First();