how to solve error for connection string in mvc?

Question

hi frnds

my connection string is

string constr = ConfigurationManager.ConnectionStrings["ConnectionString"].ConnectionString;

and in web.config

</connectionStrings>

but i am getting the error like

Object reference not set to an instance of an object.

Description: An unhandled exception occurred during the execution of the current web request. Please review the stack trace for more information about the error and where it originated in the code.

Exception Details: System.NullReferenceException: Object reference not set to an instance of an object.

Source Error:

Line 39:         { Line 40:             List<SelectListItem> items = new List<SelectListItem>(); Line 41:             string constr = ConfigurationManager.ConnectionStrings["ConnectionString"].ConnectionString; Line 42:              Line 43:              using (SqlConnection con = new SqlConnection(constr))

Ramesh Palanivel · Answer

Hi Anjali Try this connection string I think u missed provider add name = ConnectionString connectionString = Server=Sever-2019; Database=Customer ; Integrated Security=True ; providerName = System.Data.SqlClient />

Jitendra Shekhawat · Answer

Add the following connection string to the element in the Web.config file.1 XML connectionString=Data Source=(LocalDB)\v11.0;AttachDbFilename=|DataDirectory|\Movies.mdf;Integrated Security=True providerName=System.Data.SqlClient /> The following example shows a portion of the Web.config file with the new connection string added: XML

Jitendra Shekhawat · Answer

name = ConnectionStringName providerName = System.Data.SqlClient connectionString = Data Source=190.190.200.1001433;Initial Catalog=MyDatabaseName; Integrated Security=False; User ID=MyUserID;Password=MyPassword; MultipleActiveResultSets=True />

Ravi Patel · Answer

Hi  if sql server install in local system then for example for more details check this http://csharp.net-informations.com/data-providers/csharp-sql-server-connection.htm

Manas Mohapatra · Answer

Mostly ConfigurationManager.ConnectionStrings[ConnectionString] returns null so you are getting null exception. To investigate the issue first check how many connection strings. ConfigurationManager.ConnectionStrings.Count ConfigurationManager.ConnectionStrings[] ; // It takes either index as integer or connection string name. Secondly use index like: ConfigurationManager.ConnectionStrings[0].ConnectionString; Thirdly make sure that in connectionstring is present in correct web.config file of root directory.