Configura de forma dinámica tu ConnectionString usando un sqlDatasource de DevExpress

if (ConfigurationManager.ConnectionStrings["ConnectionString"] != null)
{
string connectionString = ConfigurationManager.ConnectionStrings["ConnectionString"].ConnectionString;
if (connectionString == "")
{
connectionString = @"XpoProvider=MSSqlServer;data source=;user id=;password=;initial catalog=;Persist Security Info=true";
}
CustomStringConnectionParameters connectionParameters = new CustomStringConnectionParameters(connectionString);
SqlDataSource sq = new SqlDataSource(connectionParameters);

try
{
sq.RebuildResultSchema();
winApplication.ConnectionString = connectionString;
}
catch (Exception)
{
SqlDataSourceUIHelper.ConfigureConnection(sq);
connectionString = sq.Connection.CreateConnectionString();
var config = ConfigurationManager.OpenExeConfiguration(ConfigurationUserLevel.None);
var connectionStringsSection = (ConnectionStringsSection)config.GetSection("connectionStrings");
connectionStringsSection.ConnectionStrings["ConnectionString"].ConnectionString = connectionString;
config.Save();
connectionStringsSection.SectionInformation.ProtectSection("DataProtectionConfigurationProvider");
winApplication.ConnectionString = connectionString;
}
}