How to Retrieve a Connection String from App.config in C#?
Accessing Connection Strings Stored in App.config
This guide demonstrates how to retrieve a connection string from your application's App.config
file using C#. The following code snippet shows the correct method:
string connectionString = System.Configuration.ConfigurationManager.ConnectionStrings["Test"].ConnectionString;
This line directly accesses the connection string named "Test" within the ConnectionStrings
section of your App.config
file.
To use this code, ensure you've included the necessary namespace:
using System.Configuration;
And remember, your project must have a reference to System.Configuration.dll
. Failure to include this reference will prevent the code from compiling.
The common error "Object reference not set to an instance of an object" usually arises from attempting to access a property or method of a null object. In the context of database connections, this often means the ConnectionFactory
(or a similar object) hasn't been properly initialized before being used. The method above avoids this by directly accessing the connection string from the configuration file.
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