Avoid writing the connection string in the code - entity-framework-4

Question

I already finished my first c# application which manages some tables on a sql server 2005,but I want to modify it so that it could read the connection string from a text file . By doing that I can move my application to another PC by only changing the connection string in the text file and avoid any change in the code itself. How can I do this?

Answer 1

Take a look at System.Configuration (http://msdn.microsoft.com/en-us/library/system.configuration.aspx). There are some built in methods for reading configuration files (App.Config)

Answer 2

You should use the connectionStrings section in your app/web.config file:
<connectionStrings>
<add name="DefaultConnection" providerName="System.Data.SqlClient" connectionString="Data Source=(LocalDb)\v11.0;Initial Catalog=aspnet-EditorTemplateCollectiosns-20130404170435;Integrated Security=SSPI;AttachDBFilename=|DataDirectory|\aspnet-EditorTemplateCollectiosns-20130404170435.mdf" />
</connectionStrings>
Then, when you want to access it in code, do this:
var connectionString = ConfigurationManager.ConnectionStrings["DefaultConnection"];
More on ConfigurationManager here, on configuration files here.

Answer 3

if you are developing desktop app, the preffered place is app.config
<connectionStrings>
<add name="TailorShop.Properties.Settings.TailorShopConnectionString" connectionString="Data Source=.\sqlexpress;Initial Catalog=TailorShop;Integrated Security=True" providerName="System.Data.SqlClient"/>
</connectionStrings>
Notice the connection name here, coz it is defined in the properties (double click on the properties node in your project solution explorer and go to settings)
And then you can add your connection string there. After that you will see as shown above;
Now, in-order to access it, you can do this in code;
Settings.Default.TailorShopConnectionString
In-order to work this code, you must add a reference e.g yourprojectname.properties;
using TailorShop.Properties;

Answer 4

You can manage your connection strings from a dedicated configuration section in your App.config file. Look here for more information on this.
Instead of using plain text files on non-standard solutions, see what .NET already provides. You can change the value in the config file when you move the application without needing to recompile it, because config is being read at runtime.
Here is an example:
<configuration>
<connectionStrings>
<add name="MyConnectionString"
connectionString="Data Source=.;Initial Catalog=MyDatabaseName;IntegratedSecurity=True"
providerName="System.Data.SqlClient" />
</connectionStrings>
</configuration>
Access it from code using ConfigurationManager.ConnectionStrings["MyConnectionString"].
If you really have to use a text file, then you should take a slightly different approach.
First you have to use a fixed path on the filesystem for the connection string file. You can either hardcode it in your app - a BAD PRACTICE, or use Settings or the App.config file to define the text file path.
You have to read the file programmatically. If it is plain text, you can use System.IO.File.ReadAllText(filePath); where the filePath argument is the absolute path to the file. For having the need to change the path when compiling the app, you can use the configuration/settings approach to define the physical path to the file, since changing them will not require recompilation (as earlier addressed for connection strings)