I an working on window application and i have one method for checking the connection is open if open then closed and i have a single instance of connection object but i am getting the issue "The ConnectionString property has not been initialized."
Here is my code:
public static SqlConnection connection { get; set; }
public static SqlConnection GetOpenConnnection()
{
string ConnectionString = ConfigurationManager.ConnectionStrings["connectionString"].ToString();
if (connection == null)
connection = new SqlConnection(ConnectionString);
if (connection.State == ConnectionState.Open)
connection.Close();
return connection;
}
Please tell me why i am getting this issue, if i create connection object every time then its working. so please tell me cant i have one connection object for whole application.
Related
I am new coding and I am trying to create a model DBContext.
I instantiated a connection conn using MySqlConnection. Then I perceived it didn't me allow to use conn methods (like conn.Open()).
I have found a code that uses it inside a function and it seems to work. However I couldn't understand why it has to be inside a function.
Here is my code:
public class DBContext
{
//Server=myServerAddress;Database=myDataBase;Uid=myUsername;Pwd=myPassword;
//start creating connection string
public static string ConnectString
{
get { return "Server=localhost;Database=blog;Uid=root;Pwd=root;"; }
}
public string ConnectionTest()
{
//create an instance of connection
MySqlConnection conn = new MySqlConnection();//Here I can use conn properties/methods
return "";
}
//create an instance of connection
MySqlConnection conn2 = new MySqlConnection();//Here I can't
conn2.open();
}
After reading some documentation about classes and method I understand that classes are references therefore it will not "run".
However I couldn't understand why the error when using conn2.open() is
conn2.open() does not exist in the current context.
shouldn't conn2 exist in the "class context"?
I am trying to fill list boxes with elements and been doing everything by a clean guide but I am getting connection string error when I am trying to run it.
Clearly i have done something foolish and can't understand it so a deeper explanation would be appreciated
The error
The ConnectionString property has not been initialized.
The Code
public partial class FormMain : Form
{
SqlConnection connection;
string connectionString;
public FormMain()
{
InitializeComponent();
connectionString = ConfigurationManager.ConnectionStrings["NaujasAutoSalonas.Properties.Settings.AutoSalonasConnectionString"].ConnectionString;
}
private void FormMain_Load(object sender, EventArgs e)
{
PopulateAutoKlases();
}
private void PopulateAutoKlases()
{
using (connection = new SqlConnection(connectionString));
using (SqlDataAdapter adapter = new SqlDataAdapter("SELECT * FROM AutoKlases", connection))
{
DataTable KlasesTable = new DataTable();
adapter.Fill(KlasesTable);
lstKlases.DisplayMember = "KlasesPavadinimas";
lstKlases.ValueMember = "KlasesID";
lstKlases.DataSource = KlasesTable;
}
}
}
As you have stated that the connection string property is not initialized,so I guess that your applications is not able to read the connection string from the config file.You can confirm this by putting a breakpoint in the constructor of FormMain class.
If the connection string is not being set in the constructor then you need to identify whether you have declared the connection string properly in your config file.As there could be few config files ,so it is important that you declare your connection string in the correct config file.
Or if you are defining properties for your connection string in the .settings file,you can validate if you are accessing it correctly.
I recently converted a Delphi app to C#, and I'm having an issue with an SQL connection. For some reason, when calling the CheckConnection function (shown below), IF my connection string has empty parameters, the connection is still able to .Open() without errors. Why is this? I feel like my CheckConnection function has an issue, or maybe I'm not understanding how .Open() actually works.
How it's set up - There are some textboxes that contain the hostname, user, etc. which are used as the parameters for the the connection string. Everything works fine when those are filled out correctly, but when the parameters (aka the textboxes) are all left blank, the connection still opens.
String hostname, user, password, database, protocol, query;
string connString;
IDbConnection SqlConn;
DbProviderFactory factory;
public void SetConnectionParams()
{
hostname = ServerTextBox.Text.Trim();
port = StrToIntDef(PortTextBox.Text, 3306);
user = UserIDTextBox.Text;
password = PasswordTextBox.Text;
database = DBTextBox.Text;
protocol = ProtocolTextBox.Text; //MIGHT not need
GetConnectionString(); //Get the correct connection string
}
//Gets the connection string from app.config
//The parameters for the string are all set via textboxes in diff. part of code
public void GetConnectionString()
{
if (MySqlRB.IsChecked == true) //Sets up connection for MySQL
{
var cs = ConfigurationManager.ConnectionStrings["MySQL"];
connString = ConfigurationManager.ConnectionStrings["MySQL"].ToString();
factory = DbProviderFactories.GetFactory(cs.ProviderName);
connString = String.Format(connString, hostname, port, database, user, password);
}
else //Sets up connection for MS SQL
{
if (WindowsAuth.IsChecked == true) //If windows authentication checkbox is checked
{
var cs = ConfigurationManager.ConnectionStrings["MSSQL_WA"];
connString = ConfigurationManager.ConnectionStrings["MSSQL_WA"].ToString();
factory = DbProviderFactories.GetFactory(cs.ProviderName);
connString = string.Format(connString, hostname, database);
}
else //don't use windows authentication
{
var cs = ConfigurationManager.ConnectionStrings["MSSQL"];
connString = ConfigurationManager.ConnectionStrings["MSSQL"].ToString();
factory = DbProviderFactories.GetFactory(cs.ProviderName);
connString = string.Format(connString, hostname, database, user, password);
}
}
}
//Supposed to check if the connection works or not
//This is working even if the connection string has empty parameters
public Boolean CheckConnection(bool check)
{
try
{
if (!CloseFirst && (SqlConn.State != System.Data.ConnectionState.Open))
{
return false;
}
else
{
using (SqlConn = factory.CreateConnection()) //make the connection
{
SqlConn.Close(); //make sure it's closed first just in case
SqlConn.ConnectionString = connString;
SqlConn.Open(); // Open the connection
if (SqlConn.State == System.Data.ConnectionState.Open)
{
SqlConn.Close();
return true;
}
else
{
return false;
}
}
}
}
catch
{
return false;
}
}
Example: Here's a connection string that's in my app.config for a sql server string:
<add name="MSSQL" providerName="System.Data.SqlClient"
connectionString="Data Source={0}; Initial Catalog={1}; User={2}; Password={3};" />
When debugging through the program, if I don't set any of the parameters, the string turns out like this:
connString = "Data Source=; Initial Catalog=; User=; Password=;"
That shouldn't be able to open right? It does though, and only when using SQL Server it seems, MySQL throws an error properly.
Edit:
Okay, turns out an error is not being thrown only when I use SQL Server windows authentication with this connection string:
<add name="MSSQL_WA" providerName="System.Data.SqlClient" connectionString="Data Source={0}; Initial Catalog={1}; Integrated Security=SSPI;"/>
Debugging through, the Data Source and Initial Catalog are empty, but the connection still opens. Not sure why this is?
I am new at c# and I research some project on internet. I found a project but when I start the project I get
"The ConnectionString property has not been initialized."
How can I fix it? Here is the code:
public Database(string dbType, string str, string adapter = null)
{
if (adapter != null)
{
Adapter(adapter);
}
_DbType = dbType;
var provider = DbProviderFactories.GetFactory(Adapter());
_Conn = provider.CreateConnection();
_Conn.ConnectionString = str;
_Conn.Open();
}
The error message is clear. An SqlConnection object needs a connectionstring before trying to open the connection. So when you build the connection you pass the connectionstring or set the ConnectionString property before opening.
Check this. (hope it can help you)
I can successfully log on to the database with this:
MySqlConnection conn = new MySqlConnection();
MySqlConnectionStringBuilder connString = new MySqlConnectionStringBuilder();
connString.Server = textEditServer.Text;
connString.UserID = "root";
connString.Password = textEditServerPassword.Text;
connString.Database = "geysercontrol";
conn.ConnectionString = connString.ConnectionString;
try
{
conn.Open();
Properties.Settings.Default.Properties["ConnectionString"].DefaultValue = conn.ConnectionString;
conn.Close();
}
catch (MySqlException)
{
XtraMessageBox.Show("No connection could be established");
}
But when I try to use the ConnectionString property to reconnect with different class, I get an MySQLException saying
Access denied for user 'root'#'localhost' (using password: NO)
What can be the possible causes to this? The page on possible causes on the MySQL website doesn't include my situation.
The code I use to reconnect is:
connection = new MySqlConnection();
connection.ConnectionString = (String)Properties.Settings.Default.Properties["ConnectionString"].DefaultValue;
connection.Open();
And the connectionString definitely is the same in both cases. It is:
server=localhost;User Id=root;database=geysercontrol;password=password
Add persist security info = true to the connection string I think.
If it were me though I wouldn't put connection string with a password in it in there. If you ever call Save, it will be exposed in the config file.