如何修复“ConnectionString 属性尚未初始化”

Question

大家好，我有一个关于这个方法的错误，我使用连接字符串一个 xml 文件。当我运行代码时，第一行是我的 xml 文件，它不是 工作我认为这段代码是正确的，但我找不到错误在哪里

这是连接字符串

---

    <?xml version="1.0" encoding="utf-8" ?>
 
   <conn>
     <Dbconn>
     <cstring>Server=DESKTOP-DSGBABB;Trusted_Connection=True ;database=master</cstring>
     </Dbconn>
  </conn> 

这是我的代码

 private void materialFlatButton1_Click(object sender, EventArgs e)
            {
                CreateDB();
                   }
    
     public void CreateDB()
            {
                XmlTextReader reader = null;
                reader = new XmlTextReader(filename);
    
    
                reader.WhitespaceHandling = WhitespaceHandling.None;
                while (reader.Read())
                {
                    if (reader.NodeType == XmlNodeType.Element)
                    {
                        if (reader.Name == "cstring")
                        {
                            conn = reader.ReadString();
                        }
                    } 
    
                    using (connection = new SqlConnection(conn))
                    {
                        if (connection.State != ConnectionState.Open)
                        {
    
                            connection.Open();
                        }
                        str = "CREATE DATABASE uc ON PRIMARY " +
                        "(NAME = uc, " +
                       "FILENAME = 'C:\\uc.mdf', " +
                        "SIZE = 3MB, MAXSIZE = 10MB, FILEGROWTH = 10%) " +
                       "LOG ON (NAME = uc_Log, " +
                        "FILENAME = 'C:\\uc.ldf', " +
                        "SIZE = 1MB, " +
                        "MAXSIZE = 5MB, " +
                        "FILEGROWTH = 10%)";
                         
                        connection.Close();
                        SqlCommand myCommand = new SqlCommand(str, connection);
                        try
                        {
                            connection.Open();
                            myCommand.ExecuteNonQuery();
                            MessageBox.Show("Veritabanı Başarıyla Oluşturuldu");
    
                            connection.Close();
                        }
                        catch (System.Exception ex)
                        {
                            lbls.Text = @"Error occured. 
                      + " + ex.Message.ToString();
                        }
                        connection.Close();
                    }
                }
    
            }

我将等待您的帮助

Answer 1

请尝试如下更改您的连接字符串：

Data Source=DESKTOP-DSGBABB;Initial Catalog=master;Integrated Security=True;

所以 XML 将如下所示：

<?xml version="1.0" encoding="utf-8"?>
<conn>
    <Dbconn>
        <cstring>Data Source=DESKTOP-DSGBABB;Initial Catalog=master;Integrated Security=True;</cstring>
    </Dbconn>
</conn>

在处理 XML 时使用 LINQ to XML API 会容易得多。

这是从 XML 文件中检索连接字符串的方法。

此外，SqlConnectionStringBuilder 类型将验证连接字符串的正确性。

c#

void Main()
{
    const string configFile = @"e:\Temp\configXMLFile.xml";
    XDocument xdoc = XDocument.Load(configFile);
        
    SqlConnectionStringBuilder builder = new SqlConnectionStringBuilder();
    builder.ConnectionString = xdoc.Descendants("Dbconn").Elements("cstring").FirstOrDefault().Value;
    using (connection = new SqlConnection(conn))
    {
        ...
    }
}