An application of mine uses LINQ-to-SQL extensively, and it is now a requirement of the application to be able to switch which database it is looking at at runtime - so essentially I would like to be able to choose the connection string of my data context when I declare it.
Is there an easy way of doing this?
Just call :
DataContext context = new DataContext ("cxstring");
You could use an App.config to store your Connection Strings then use them to populate a drop down box or something. Then use the selected Connection string in the constructor of your LINQ2SQL data context.
App Config:
<configuration>
<connectionStrings>
<add key="ConString1" connectionString="ConnectionStringGoesHere"/>
<add key="ConString2" connectionString="ConnectionStringGoesHere"/>
</connectionStrings>
Use the ConfigurationManager class to access your connection strings.
string conString = ConfigurationManager.ConnectionStrings["ConString1"].ConnectionString;
You can also enumerate over them or set them as datasource to populate a drop down box.
Then simply pass the selected string in as the first parameter in your LINQ2SQL datacontext constructor.
MyModelDataContext context = new MyModelDataContext(selectedConString);
If you mean by switching which database your application is looking at ,Test database and production database , simply you can make two connection string in your web.config file with the same key but has different connection string and comment one of them according to the desired database
<add name="MyConnectioString" connectionString="Data Source=myServer;Initial Catalog=ProductionDB;" providerName="System.Data.SqlClient" />
<!--<add name="MyConnectioString" connectionString="Data Source=myServer;Initial Catalog=TestDB;" providerName="System.Data.SqlClient" />-->
by comment and uncomment you can switch between the 2 databases in run time.
to choose the connection string of your context provide it with its constructor
DataContext Productioncontext = new DataContext ("MyConnectioString");
