Declaring connection string in a class

Question

Hi Declaring connection string in a class which is declared in web.config file if do like this showing an error Non Invocable member using System.Data.SqlClient; using System; using System.Collections.Generic; using System.Linq; using System.Web; using System.Configuration; namespace CSharpTutorial { public class MyFunctClass { string connstr = ConfigurationManager.ConnectionStrings (myConnectionString).connectionString; } } Plz help

Sanjeeb Lenka · Answer

try like this: in class: using System; using System.Collections.Generic; using System.Linq; using System.Web; using System.Configuration; using System.Data.SqlClient; using System.Data; namespace CSharpTutorial { public class MyFunctClass { string connstr = ConfigurationManager.ConnectionStrings[ConStr].ToString(); SqlConnection cn; SqlCommand cmd; public DataTable readData(int id) { cn = new SqlConnection(connstr); cmd = new SqlCommand(); cmd.Connection = cn; cmd.CommandText = Select * From testClass1 Where ID=' + id + '; SqlDataReader dr; cn.Open(); dr = cmd.ExecuteReader(); DataTable dt = new DataTable(testClass1); dt.Load(dr); cn.Close(); return dt; } } } -------------------------------------------------------------- protected void btnSearch_Click(object sender EventArgs e) { MyFunctClass a = new MyFunctClass(); DataTable dtn = a.readData(Convert.ToInt32(tbSearch2.Text)); tbUser.Text = dtn.Rows[0][UserName].ToString(); tbId.Text = dtn.Rows[0][ID].ToString(); tbDesig.Text = dtn.Rows[0][Desig].ToString(); } now you have check by putting debug points. 1. check your are getting the connection string or not. 2. are you able to get data in to datatable or not. 3. if you got any exception in any line make it bold and past so we can get a clear idea.

Aman Jen · Answer

Yess..Its working Fine Now..Thankx...:)

Sanjeeb Lenka · Answer

are you able to get the data. if not then share your web.confg

Aman Jen · Answer

Done...Connection string name was wrong...:)

Aman Jen · Answer

I have updated error line plz have look

Sanjeeb Lenka · Answer

in which line you are getting error.

Aman Jen · Answer

Now throwing exception .. Object reference not set to an instance of an object.} using System.Data.SqlClient; using System; using System.Data; using System.Collections.Generic; using System.Linq; using System.Web; using System.Configuration; namespace CSharpTutorial { public class MyFunctClass { Here----->>>if I use Static //static string connstr = ConfigurationManager.ConnectionStrings[myConnectionString].ConnectionString; //static string connstr = ConfigurationManager.ConnectionStrings[myConnectionString].ToString(); string connstr = ConfigurationManager.ConnectionStrings[myConnectionString].ToString(); public SqlConnection cn; public MyFunctClass() { cn = new SqlConnection(connstr); } //SqlConnection cn = new SqlConnection(connstr); SqlCommand cmd= new SqlCommand(); SqlDataReader dr; public DataTable readData(int id) { cmd.Connection = cn; cmd.CommandText = Select * From testClass1 Where ID='+ id +'; cn.Open(); dr = cmd.ExecuteReader(); DataTable dt = new DataTable(testClass1); dt.Load(dr); return dt; } } } ---------------------------------- protected void btnSearch_Click(object sender EventArgs e) { Here if I dont use static....>>> MyFunctClass a = new MyFunctClass(); DataTable dtn = a.readData(Convert.ToInt32(tbSearch2.Text)); tbUser.Text = dtn.Rows[0][UserName].ToString(); tbId.Text = dtn.Rows[0][ID].ToString(); tbDesig.Text = dtn.Rows[0][Desig].ToString(); }

Sanjeeb Lenka · Answer

try like this: protected void btnSearch_Click(object sender EventArgs e) { MyFunctClass a = new MyFunctClass(); DataTable dtn = a.readData(Convert.ToInt32(tbSearch2.Text)); tbUser.Text = dtn.Rows[0][UserName].ToString(); tbId.Text = dtn.Rows[0][ID].ToString(); tbDesig.Text = dtn.Rows[0][Desig].ToString(); }

Aman Jen · Answer

Yes here in class using System.Data.SqlClient; using System; using System.Data; using System.Collections.Generic; using System.Linq; using System.Web; using System.Configuration; namespace CSharpTutorial { public class MyFunctClass { //string connstr = ConfigurationManager.ConnectionStrings[myConnectionString].ConnectionString; //static string connstr = ConfigurationManager.ConnectionStrings[myConnectionString].ToString(); string connstr = ConfigurationManager.ConnectionStrings[myConnectionString].ToString(); public SqlConnection cn; public MyFunctClass() { cn = new SqlConnection(connstr); } //SqlConnection cn = new SqlConnection(connstr); SqlCommand cmd= new SqlCommand(); SqlDataReader dr = new SqlDataReader(); public DataTable readData(int id) { cmd.Connection = cn; cmd.CommandText = Select * From testClass1 Where ID='+ id +'; cn.Open(); dr = cmd.ExecuteReader(); DataTable dt = new DataTable(testClass1); dt.Load(dr); return dt; } } }

Iftikar Hussain · Answer

have you declare readData()

Aman Jen · Answer

Hi Even If I do that way..showing same error..Non Invocable member protected void btnSearch_Click(object sender EventArgs e) { MyFunctClass a = new MyFunctClass(); DataTable dtn = a.readData(Convert.ToInt32(tbSearch2.Text)); tbUser.Text = dtn.Rows(0)(UserName).ToString; tbId.Text = dtn.Rows(0)(ID).ToString; tbDesig.Text = dtn.Rows(0)(Desig).ToString; }

Rosi Sreenivasa Reddy · Answer

string connStr = ConfigurationManager.ConnectionStrings[myConnectionString].ToString(); or string connstr = ConfigurationManager.ConnectionStrings[myConnectionString].connectionString; what is the difference between these two

Iftikar Hussain · Answer

that is a reason I have suggest you not to use static field

Aman Jen · Answer

Hey...showing same error for this stuff...Non invocable Member protected void btnSearch_Click(object sender EventArgs e) { MyFunctClass a = new MyFunctClass(); DataTable dtn = a.readData(Convert.ToInt32(tbSearch2.Text)); tbUser.Text = dtn.Rows(0)(UserName).ToString; tbId.Text = dtn.Rows(0)(ID).ToString; tbDesig.Text = dtn.Rows(0)(Desig).ToString; }

Aman Jen · Answer

Yups..working..:)

Iftikar Hussain · Answer

you should use connection in constructor static is not good way to declare it public class MyFunctClass { string connstr = ConfigurationManager.ConnectionStrings[myConnectionString].ToString(); public SqlConnection cn; public MyFunctClass() { cn = new SqlConnection(connstr); } }

Sanjeeb Lenka · Answer

try this: using System.Data.SqlClient; using System; using System.Collections.Generic; using System.Linq; using System.Web; using System.Configuration; namespace CSharpTutorial { public class MyFunctClass { static string connstr = ConfigurationManager.ConnectionStrings[myConnectionString].ToString(); SqlConnection cn = new SqlConnection(connstr); } }

Aman Jen · Answer

Showing same error....

Iftikar Hussain · Answer

try like this public class MyFunctClass { string connstr = ConfigurationManager.ConnectionStrings[myConnectionString].ToString(); public SqlConnection cn; public MyFunctClass() { cn = new SqlConnection(connstr); } }

Aman Jen · Answer

using System.Data.SqlClient; using System; using System.Collections.Generic; using System.Linq; using System.Web; using System.Configuration; namespace CSharpTutorial { public class MyFunctClass { string connstr = ConfigurationManager.ConnectionStrings[myConnectionString].ToString(); public SqlConnection cn = new SqlConnection(connstr); } }

Iftikar Hussain · Answer

can you share the complete code?

Aman Jen · Answer

field initializer cannot reference the nonstatic field even if do like this same error public Static SqlConnection cn = new SqlConnection(connstr);

Iftikar Hussain · Answer

what error you are getting?

Aman Jen · Answer

Hi When I am passing this connection string to sqlconnection object showing an error... string connstr = ConfigurationManager.ConnectionStrings[myConnectionString].ConnectionString; SqlConnection cn = new SqlConnection(connstr); Plz help

Iftikar Hussain · Answer

use the below link for converting VB.NET to C# http://www.developerfusion.com/tools/convert/vb-to-csharp/ Regards Iftikar

Iftikar Hussain · Answer

Hi Try like this public class MyFunctClass { string connstr = ConfigurationManager.ConnectionStrings[myConnectionString].connectionString; } Regards Iftikar

Sanjeeb Lenka · Answer

try this: string connStr = ConfigurationManager.ConnectionStrings [myConnectionString] .ToString(); or string connstr = ConfigurationManager.ConnectionStrings [myConnectionString]. connectionString;