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)
Related
I have a project that uses entity framework data model(.edmx) in it's data layer.I want to add work station id in connection string to store it during create log in database.
This is what I do:
var d = new PresentModelConnectionString();
string connectionString = d.Database.Connection.ConnectionString;
string lastCharacter = connectionString.Substring(connectionString.Length - 1, 1);
if (lastCharacter == ";")
{
connectionString += $"workstation id={Helpers.UserId.ToString()}";
}
else
{
connectionString += $";workstation id={Helpers.UserId.ToString()}";
}
d.Database.Connection.ConnectionString = connectionString;
return d;
But when it tries to connect to database and get data returns The login for user sa failed.When I remove this line:
d.Database.Connection.ConnectionString = connectionString;
It works fine.
This is the connection string:
<add name="PresentModelConnectionString" connectionString="metadata=res://*/PresentModel.csdl|res://*/PresentModel.ssdl|res://*/PresentModel.msl;provider=System.Data.SqlClient;provider connection string="data source=192.168.1.101\sql2014;initial catalog=MIS;user id=sa;password=sa_123;connect timeout=600000000;MultipleActiveResultSets=True;App=EntityFramework"" providerName="System.Data.EntityClient" />
How can I include work station id dynamically to connection string?
Thanks
After searching several hours I found this solution, it change the connection string of entity framework database first model.As Alex recommended in comments I should use SqlConnectionStringBuilder to make connection string.
Create a partial class for model context in a separate file for adding constructor that gives connection string as parameter:
public partial class PresentModelConnectionString
{
public PresentModelConnectionString(string connectionString):base(connectionString)
{
}
}
Make connection string:
//connection string in web.config
//Data Source=192.168.1.101\sql2014;Initial Catalog=MIS_Keshavarzi_980906;user id=sa;pwd=sa_123; Connect Timeout=60000;
string connectionString =
System.Configuration.ConfigurationManager.AppSettings["ABSConnectionString"];
SqlConnectionStringBuilder connectionStringBuilder = new
SqlConnectionStringBuilder(connectionString);
connectionStringBuilder.WorkstationID = Helpers.UserId.ToString(); //get work station id
connectionStringBuilder.ApplicationName = "EntityFramework"; //set application name
For modifying the model connection string use EntityConnectionStringBuilder:
EntityConnectionStringBuilder entityConnectionBuilder = new
EntityConnectionStringBuilder();
entityConnectionBuilder.Metadata =
"res://*/PresentModel.csdl|res://*/PresentModel.ssdl|res://*/PresentModel.msl";
entityConnectionBuilder.Provider = "System.Data.SqlClient";
entityConnectionBuilder.ProviderConnectionString =
connectionStringBuilder.ConnectionString;
PresentModel should change with your model name.
Finally create a new instance of model context with this connection string:
var entityContext = new
PresentModelConnectionString(entityConnectionBuilder.ConnectionString);
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 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.
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?
Please help with this coding error? I am new to C# and SQL and need some fast help.
This is the code I have already, the problem comes when I debug it throws an error when I get to
string ConnectionString = ConfigurationManager
.ConnectionStrings["Student1"]
.ConnectionString;
The error message is
null reference exception was unhandled.
No matter what I do I can't seem to fix this error. Any ideas?
static class Program
public static SqlConnection GetConnection
{
get
{
string ConnectionString = ConfigurationManager
.ConnectionStrings["Student1"]
.ConnectionString;
SqlConnection con = new SqlConnection(ConnectionString);
con.Open();
return con;
}
}
You must verify that you have connection string in your configuration file
<configuration>
<connectionStrings>
<add name="Student1"
connectionString="...."
providerName="...." />
</connectionStrings>
....
In addition to the other answer(s) it might be worth pointing out why you get this error.
Basically your code here:
string ConnectionString = ConfigurationManager.ConnectionStrings["Student1"].ConnectionString;
Is trying to access the ConfigurationManager.ConnectionStrings collection, the indexer for this collection returns a NULL if no value is found (some other collections will raise an index out of range exception)
It is likely the value is NULL because you are missing the connection string from your app.config - but since you aren't checking to see if the connection string object returned by the indexer is null and you are trying to use it's value, a null reference exception is thrown
A good check would be:
var conn = ConfigurationManager.ConnectionStrings["Student1"];
if(conn == null) throw new Exception("No connection string in config file"); // etc
string ConnectionString = conn.ConnectionString;
This way you could throw a more meaningful exception if the connection string was absent