如何在 C# 中更新 app.config 连接字符串数据源值？

Question

Configuration config = ConfigurationManager.OpenExeConfiguration(ConfigurationUserLevel.None);
config.ConnectionStrings.ConnectionStrings["MyConnectionString",String.Format("DataSource={0};")].ConnectionString=textBox1.Text;
config.Save(ConfigurationSaveMode.Modified, true);
ConfigurationManager.RefreshSection("connectionStrings");

我在第二行遇到了麻烦。我似乎无法使语法正确。如您所见，我只想更新 DataSource 值。例如，如果当前值为 Data Source=PC001\SQL2008EXPRESS，我希望它更新为客户端在 textBox1 中输入的内容。

编辑：示例连接字符串

<add name="ERPDatabaseTables" connectionString="metadata=res://*/ERPTables.csdl|res://*/ERPTables.ssdl|res://*/ERPTables.msl;provider=System.Data.SqlClient;provider connection string=&quot;Data Source=PC001\SQL2008EXPRESS;Initial Catalog=MyDatabase.mdf;Integrated Security=True;MultipleActiveResultSets=True&quot;" providerName="System.Data.EntityClient"/>

所以只想更新 Data Source=PC001\SQL2008EXPRESS 部分

Answer 1

你真正想要的是：

Configuration config = 
    ConfigurationManager.OpenExeConfiguration(ConfigurationUserLevel.None);

// Because it's an EF connection string it's not a normal connection string
// so we pull it into the EntityConnectionStringBuilder instead
EntityConnectionStringBuilder efb = 
    new EntityConnectionStringBuilder(
        config.ConnectionStrings.ConnectionStrings["ERPDatabaseTables"]
            .ConnectionString);

// Then we extract the actual underlying provider connection string
SqlConnectionStringBuilder sqb = 
    new SqlConnectionStringBuilder(efb.ProviderConnectionString);

// Now we can set the datasource
sqb.DataSource = textBox1.Text;

// Pop it back into the EntityConnectionStringBuilder 
efb.ProviderConnectionString = sqb.ConnectionString;

// And update...
config.ConnectionStrings.ConnectionStrings["ERPDatabaseTables"]
    .ConnectionString = efb.ConnectionString;

config.Save(ConfigurationSaveMode.Modified, true);
ConfigurationManager.RefreshSection("connectionStrings");

这假定：

1. 您的 EF 连接字符串存在于应用的配置文件中

2. 您有对System.Data.Entity的引用