Read connection string from web.config

Question

How can I read a connection string from a web.config file into a public class contained within a class library?

I've tried:

WebConfigurationManager

ConfigurationManager

But these classes are not recognized within my class library.

score 543 · Answer 1 · edited Nov 04 '14 at 12:31

543

You need to add a reference to System.Configuration and then use:

System.Configuration.ConfigurationManager.
    ConnectionStrings["connectionStringName"].ConnectionString;

edited Nov 04 '14 at 12:31

Bart

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answered May 26 '11 at 06:08

Muhammad Akhtar

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20

[MSDN, System.configuration](http://msdn.microsoft.com/zh-tw/library/system.configuration.configurationmanager.aspx). It needs `System.Configuration.dll`. – AechoLiu Jul 05 '14 at 07:42

score 188 · Accepted Answer · edited Jun 22 '16 at 08:25

188

Add System.Configuration as a reference.

For some bizarre reason it's not included by default.

edited Jun 22 '16 at 08:25

Liam

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answered May 26 '11 at 06:07

peteisace

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score 66 · Answer 3 · edited Mar 10 '15 at 20:14

66

C#

// Add a using directive at the top of your code file    
using System.Configuration;

// Within the code body set your variable    
string cs = ConfigurationManager.ConnectionStrings["connectionStringName"].ConnectionString;

VB

' Add an Imports statement at the top of your code file    
Imports System.Configuration

' Within the code body set your variable    
Dim cs as String = ConfigurationManager.ConnectionStrings("connectionStringName").ConnectionString

edited Mar 10 '15 at 20:14

Zack

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answered Jun 18 '13 at 16:48

MDM

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"Add a reference at the top of your code file" => that's a using directive, not a reference! – Mishax Aug 01 '14 at 14:54

score 27 · Answer 4 · edited Aug 19 '12 at 23:33

27

Add System.Configuration as a reference then:

 using System.Configuration;

 ...

 string conn = 
    ConfigurationManager.ConnectionStrings["ConnectionName"].ConnectionString;

edited Aug 19 '12 at 23:33

Kev

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answered Aug 08 '11 at 13:31

nirmus

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score 20 · Answer 5 · edited Nov 09 '12 at 16:09

20

I guess you need to add a reference to the System.Configuration assembly if that have not already been added.

Also, you may need to insert the following line at the top of your code file:

using System.Configuration;

edited Nov 09 '12 at 16:09

Md Ashaduzzaman

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answered May 26 '11 at 06:07

Akram Shahda

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score 17 · Answer 6 · edited Jan 07 '20 at 10:10

17

using System;
using System.Collections.Generic;
using System.Configuration;
using System.Data.SqlClient;
using System.Drawing;
using System.Linq;
using System.Web;
using System.Web.UI;
using System.Web.UI.DataVisualization.Charting;
using System.Web.UI.WebControls;

C#

string constring = ConfigurationManager.ConnectionStrings["ABCD"].ConnectionString;
                using (SqlConnection con = new SqlConnection(constring))

BELOW WEB.CONFIG FILE CODE

<connectionStrings>
    <add name="ABCD" connectionString="Data Source=DESKTOP-SU3NKUU\MSSQLSERVER2016;Initial Catalog=TESTKISWRMIP;Integrated Security=True" providerName="System.Data.SqlClient"/>
  </connectionStrings>

In the above Code ABCD is the Connection Name

edited Jan 07 '20 at 10:10

Dariusz Woźniak

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answered Aug 24 '17 at 07:47

subramanya46

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**Addition:** Besides the indexer that accepts the name of the connection string, it is also allowed to use integer indices - which is useful if you want to read all connection strings in a `for` loop (`for (int i = 0; i < numOfConnections; i++) { var conn = ConfigurationManager.ConnectionStrings[i]; ... }`) and make them selectable in a combobox. With `var numOfConnections = ConfigurationManager.ConnectionStrings.Count;` you can determine how many connection strings exist. In this example `conn.Name` contains the name of the connection. – Matt Dec 05 '19 at 15:39

score 15 · Answer 7 · edited Mar 30 '16 at 13:38

15

In VB : This should work

ConfigurationManager.ConnectionStrings("SQLServer").ConnectionString

In C# it would be (as per comment of Ala)

ConfigurationManager.ConnectionStrings["SQLServer"].ConnectionString

edited Mar 30 '16 at 13:38

Marcel

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answered May 26 '11 at 06:11

Alaa Alweish

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Those parentheses need to be brackets. – Charles Burns Dec 13 '12 at 19:01
1

@CharlesBurns,Thanks, I wrote in VB by mistake, in C# sure it should be `ConfigurationManager.ConnectionStrings["SQLServer"].ConnectionString` – Alaa Alweish Dec 13 '12 at 20:01
Ahh, I didn't even realize that was VB. I thought it was a typo. In a way, my mistake too. – Charles Burns Dec 13 '12 at 21:05

score 11 · Answer 8 · edited Jun 22 '16 at 08:51

You have to invoke this class on the top of your page or class :

using System.Configuration;

Then you can use this Method that returns the connection string to be ready to passed to the sqlconnection object to continue your work as follows:

    private string ReturnConnectionString()
    {
       // Put the name the Sqlconnection from WebConfig..
        return ConfigurationManager.ConnectionStrings["DBWebConfigString"].ConnectionString;
    }

Just to make a clear clarification this is the value in the web Config:

  <add name="DBWebConfigString" connectionString="....." />   </connectionStrings>

In Web project is better to use WebConfigurationManager in System.Web.Configuration. — BJladu4, Dec 15 '15 at 09:02

score 9 · Answer 9 · edited Mar 07 '13 at 15:26

9

using System.Configuration;


string conn = ConfigurationManager.ConnectionStrings["ConStringName"].ToString();

edited Mar 07 '13 at 15:26

NoWar

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answered Jan 29 '13 at 07:21

Saravanan G

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score 4 · Answer 10 · edited Oct 12 '13 at 09:18

4

using System.Configuration;


string connString = ConfigurationManager.ConnectionStrings["ConStringName"].ToString();

Remember don't Use ConnectionStrings[index] because you might of Global machine Config and Portability

edited Oct 12 '13 at 09:18

Rafael Herscovici

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answered Aug 14 '13 at 11:16

cyberspiritwebsolutions ugo

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score 2 · Answer 11 · edited Aug 20 '12 at 05:37

2

First add this:

using System.Configuration;

edited Aug 20 '12 at 05:37

Conner

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answered Aug 18 '12 at 21:54

Ali

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score 1 · Answer 12 · answered Aug 26 '15 at 21:06

Everybody seems to be suggesting that adding

using System.Configuration;

which is true.

But might I suggest that you think about installing ReSharper's Visual Studio extension?

With it installed, instead of seeing an error that a class isn't defined, you'll see a prompt that tells you which assembly it is in, asking you if you want it to add the needed using statement.

Read connection string from web.config

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