Connection String Is not Working Object instance reference is null

Question

//'Object reference not set to an instance of an object.' Please Do not mark it as redundant question . I have tried almost all the methods to make a connection string

first one is by :

string connectionString = ConfigurationManager.ConnectionStrings["ClinicalConnectionString"].ConnectionString;

the second one :

   string connectionstringgg = Properties.Settings.Default.ClinicalConnectionString;

third method is by :

 ConnectionStringSettings connectionSetting = ConfigurationManager.ConnectionStrings["ClinicalConnectionString"];

//the name of the connection i made

SqlConnection connection = new SqlConnection(connectionString);

In the app config:

<connectionStrings>
    <add name="ClinicalDAO.Properties.Settings.ClinicalConnectionString"
        connectionString="Data Source=DESKTOP-I07DSQC;Initial Catalog=db_clinics;Integrated Security=True"
        providerName="System.Data.SqlClient" />
</connectionStrings>

In the web config

  <connectionStrings>
    <add name="ClinicalDAO.Properties.Settings.ClinicalConnectionString"
        connectionString="Data Source=DESKTOP-I07DSQC;Initial Catalog=db_clinics;Integrated Security=True"
        providerName="System.Data.SqlClient" />
  </connectionStrings>

ANY HELP PLEASE it still give me the same error : /////'Object reference not set to an instance of an object.'///

The name needs to match the name property in your config file, not just the last part, so e.g. "ClinicalDAO.Properties.Settings.ClinicalConnectionString" — sellotape, Jul 29 '18 at 14:10
You can most likely run the code in a debugger and check what the ConnectionStrings collection contains. But in any case what was said is true, the whole `name` must be used to access the string. — Sami Kuhmonen, Jul 29 '18 at 14:11
Possible duplicate of [What is a NullReferenceException, and how do I fix it?](https://stackoverflow.com/questions/4660142/what-is-a-nullreferenceexception-and-how-do-i-fix-it) — Camilo Terevinto, Jul 29 '18 at 14:33
You said *"Please Do not mark it as redundant question"* but I'm afraid there is nothing special here, just a regular NullReferenceException, which you need to learn to diagnose. In the first example you give, the value before `.ConnectionString` will return null because the name you asked it to look for in the config doesn't exist. — Richardissimo, Jul 29 '18 at 16:49

Just Fair · Answer 1 · 2018-07-29T15:17:50.833

There are many ways to connect to your SQL Server database within a C# app.

The First way, that is not recommended, is hard coding:

public void CreateMySqlConnection()
{
    MySqlConnectionStringBuilder myCSB = new MySqlConnectionStringBuilder();
    myCSB.Port = 3307;
    myCSB.Host = "localhost";
    myCSB.UserId = "root";
    myCSB.Password = "mypassword";
    myCSB.Direct = true;
    myCSB.Compress = true;
    myCSB.Database = "demobase";
    myCSB.MaxPoolSize = 150;
    myCSB.ConnectionTimeout = 30;
    MySqlConnection myConnection = new MySqlConnection(myCSB.ConnectionString);
}

from: https://www.devart.com/dotconnect/connection-strings.html?gclid=CjwKCAjwy_XaBRAWEiwApfjKHt-Yn6Ja43anKj0cvAzDHL5eNDHKvaxwnq5IEsVyHY-rR3GECsa6shoCZH8QAvD_BwE

The second way, anwsering the question being already anwsered by @sellotape at the author comments, is puting the connection string at you web.config:

<add name="MovieDB"
     connectionString="Data Source=LocalDb)\MSSQLLocalDB;Initial Catalog=aspnet-MvcMovie;Integrated Security=SSPI;AttachDBFilename=|DataDirectory|\Movies.mdf"     
     providerName="System.Data.SqlClient"/>

to read it:

System.Configuration.Configuration rootWebConfig =
            System.Web.Configuration.WebConfigurationManager.OpenWebConfiguration("/MyWebSiteRoot");
        System.Configuration.ConnectionStringSettings connString;
        if (rootWebConfig.ConnectionStrings.ConnectionStrings.Count > 0)
        {
            connString =
                rootWebConfig.ConnectionStrings.ConnectionStrings["MovieDB"];
            if (connString != null)
                Console.WriteLine("MovieDB connection string = \"{0}\"",
                    connString.ConnectionString);
            else
                Console.WriteLine("No MovieDB connection string");
        }

The name at your web.config tag 'name'

    <add name="MovieDB".....

has to be the same one from your c# code:

    connString = rootWebConfig.ConnectionStrings.ConnectionStrings["MovieDB"]

You don´t need to specify a large name as you did: "ClinicalDAO.Properties.Settings.ClinicalConnectionString"

Make it smaller and simple.

from: https://msdn.microsoft.com/en-us/library/ms178411.aspx

Don´t forget to secure your connection string at your web.config. Please, read this: https://msdn.microsoft.com/en-us/library/ms178372.aspx

I already have the answer. But you have made a really well answer with references and mentioned the righteous way , the hardcoded and how to make it secure. Thank you. — Mark Dibeh, Jul 29 '18 at 15:38
The first way is also not recommended as it applies to MySql and the question is tagged SQL Server — Richardissimo, Jul 29 '18 at 16:50

Connection String Is not Working Object instance reference is null

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