C# 从 app.config 获取 ConnectionString
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Get ConnectionString from app.config
提问by Daniel Sh.
I'm pretty sure there's some quick and easy error in this code but somehow I've spent the last 2 hours with this and couldn't solve it.
我很确定这段代码中存在一些快速而简单的错误，但不知何故，我在过去的 2 个小时里一直在解决这个问题，但无法解决。
App.config:
App.config：
<configuration>
<connectionStrings>
<add name="BO"
connectionString="Data Source=MyServer;Initial Catalog=BO;User ID=WebUser;Password=MyPasswd"
providerName="System.Data.SqlClient" />
</connectionStrings>
</configuration>
Class.cs:
Class.cs：
string connectionString = getNewConnection();
using (SqlConnection conn = new SqlConnection(connectionString)) { code }
Method.
方法。
public static string getNewConnection()
{
return ConfigurationManager.ConnectionStrings["BO"].ConnectionString;
}
Error:
错误：
Object reference not set to an instance of an object
你调用的对象是空的
on the line :
在线上 ：
return ConfigurationManager.ConnectionStrings["BO"].ConnectionString;
EDIT:
编辑：
采纳答案by Andrew Hagner
It should be:
它应该是：
ConfigurationManager.ConnectionStrings["BO"].ConnectionString;
Edit:
编辑：
You will need the corresponding libraries as well if you don't have them yet, as mentioned in the below answers I think its System.Configuration
如果您还没有它们，您也将需要相应的库，如以下答案中所述，我认为它的 System.Configuration
So in full you should have:
所以完整的你应该有：
public static string getNewConnection()
{
return ConfigurationManager.ConnectionStrings["BO"].ConnectionString;
}
回答by etlds
Did you use the WebConfigurationManager?
你使用了 WebConfigurationManager 吗？
string MyConnectionString = System.Web.Configuration.WebConfigurationManager.ConnectionStrings["BO"].ConnectionString;
回答by ALI VOJDANIANARDAKANI
Use these codes in the Class :
在 Class 中使用这些代码：
class Connection
{
public static string con
{
get
{
return System.Configuration.ConfigurationManager.ConnectionStrings["sql"].ConnectionString;
}
}
}
回答by daszarrin
Add a reference to System.Configuration.dll, and you should be able to use the System.Configuration.ConfigurationManager.
添加对 System.Configuration.dll 的引用，您应该能够使用 System.Configuration.ConfigurationManager。
