This is a noob question but I have been stuck here for a few hours so I need to get passed this. I have this Windows App that performs a simple function. It makes a trip to the DB and checks if a specific record exists and if it does then perform some operation. However it just doesn't want to read the connection string - it comes as null all the time. I keep getting null every time I initialize my connection string. What could I be doing wrong. I only have one connection string named App.config.
Class File:
private class ClassA
{
private string myConnectionString = "";
private SqlConnection mySQLConnection;
private SqlCommand mySQLCommand;
private int CheckIfSerialNumberExists(UInt64 ColumnToCheck)
{
int countResult = 0;
myConnectionString = ConfigurationManager.ConnectionStrings["ConnectionStringName"].ConnectionString; //I get an object reference null here when the compiler executes this line. I have been using this structure for years and never got any issues
using (mySQLConnection = new SqlConnection(myConnectionString))
{
string procName = "SELECT Count(*) ColumnName FROM Table WHERE ColumnName='" + ColumnToCheck + "'";
mySQLCommand = new SqlCommand(procName, mySQLConnection);
mySQLConnection.Open();
countResult = (int)mySQLCommand.ExecuteScalar();
}
return countResult;
}
private void someFunc()
{
//Test value: 5
if(CheckIfSerialNumberExists(5) > 0)
{
//Don't do anything
}
else
{
//Save to DB
}
}
}
Config File:
<?xml version="1.0" encoding="utf-8"?>
<configuration>
<connectionStrings>
<add name="ConnectionStringName"
connectionString="Data Source=ServerName;Initial Catalog=DatabaseName;Persist Security Info=True;User ID=**;Password=****"
providerName="System.Data.SqlClient" />
</connectionStrings>
<startup><supportedRuntime version="v4.0" sku=".NETFramework,Version=v4.5.1"/></startup>
</configuration>
So here is the quick fix:
In my windows app I am referencing a class library project. I had only added the connection string in that project. I added it to my windows app project and there we go, all was working. Really feel like an idiot.
Related
I am trying to use a button that will add to my two columns in my database. I have placeholder values in there currently but will eventually be using 2 pop ups to read in those values.
My question is: how do I get the connection string? I don't know what to put there or where to get that data.
private void button_AddPartNumber_Click(object sender, EventArgs e)
{
string cmdString = "INSERT INTO Part_Numbers (Part_Number, Barcode_Number) VALUES (#val1, #val2)";
string connectionString = "I DONT KNOW WHAT TO PUT HERE";
using (SqlCommand connection = new SqlCommand(connectionString))
{
using (SqlCommand comm = new SqlCommand())
{
comm.Connection = connectionString;
comm.CommandText = cmdString;
comm.Parameters.AddWithValue("#val1", "L-0G004-0830-xx"); //placeholder value
comm.Parameters.AddWithValue("#val2", "asdf1234"); // placehold value
}
}
} // end button_AddPartNumber_Click()
Well, what database are you using? For example, SQLServer? Oracle? MySQL?
In SQLServer, at least, the connection string is defined in the web.config, or app.config, and has syntax similar to the following:
<appSettings>
<add key="ConnectionStringName" value="AppName"/>
</appSettings>
<connectionStrings>
<add name="AppName" connectionString="Data Source=DataSourceName; Initial Catalog=DataBaseName; user id=UserID; password=Password" providerName="System.Data.SqlClient"/>
</connectionStrings>
Something like that. There's probably something I'm missing, but without testing it out in your code, I'm blanking on what that might be.
This how you extract the connection string from your code if the connection string is properly set in the web.config:
var connectionString = ConfigurationManager.ConnectionStrings["AppName"].ConnectionString;
I have developed a Window Service using SQL Database currently in my DB is full of Record so query execuction taking much time while default command timeout is 30S but I want to increase it to 120S one option is
com.CommandTimeout = 120;
but I have many methods in my Application so I want to set it from APP.config file so it will be applicable for Application level, can anyone please tell me how could I achive this
Thanks
The easiest way to achieve this is to add a new entry in <appSettings> something like this:
<appSettings>
<add key="commandTimeout" value="3000" />
</appSettings>
Afterwards, create a CommandFactory class that will populate the value
class CommandFactory
{
public static int CommandTimeout
{
get
{
int commandTimeout = 0;
var configValue = ConfigurationManager.AppSettings["commandTimeout"];
if(int.TryParse(configValue, out commandTimeout))
return commandTimeout;
return 120;
}
}
public static SqlCommand CreateCommand(SqlConnection connection)
{
var command = new SqlCommand()
{
Connection = connection,
CommandTimeout = CommandTimeout
};
return command;
}
}
Now, in your code, instead of just instantiating a new SqlCommand just call the CommandFactory method:
using(var command = CommandFactory.CreateCommand(yourConnection))
{
//
}
use this in app.config file
<configuration>
<appSettings>
<add key="connectioStringName" value="Data Source=source;Initial Catalog=tableName;User Id=databaseName;Password=password;Connection Timeout=3000"/>
</appSettings>
</configuration>
I'm a 17 year old software engineering student and am having trouble with linking my sql database to my C# Win App. I was able to accomplish this task using a access database but the database needs to be in SQL. Any Help would be greatly appreciated!
The code i have so far is :
Form1.cs
using System;
using System.Collections.Generic;
using System.ComponentModel;
using System.Data;
using System.Drawing;
using System.Linq;
using System.Text;
using System.Threading.Tasks;
using System.Windows.Forms;
using System.Data.OleDb; // all Non-SqlServer Databases ie oracle, access, sqlLite
using System.Configuration;
namespace SqlWinApp
{
public partial class Form1 : Form
{
// Declare and init data objects
// Connect to an external data source
//OleDbConnection cnDataCon =
// new OleDbConnection("Provider=Microsoft.ACE.OLEDB.12.0; Data Source=H:/SEWD/ASP/dataTestJr/App_Data/dbWaxStax.accdb");
SqlConnection cnDataCon =
new SqlConnection(ConfigurationManager.ConnectionStrings["cnExternalData"].ConnectionString);
// dataset: Container object for data tables
DataSet dsData = new DataSet();
public Form1()
{
InitializeComponent();
}
private void Form1_Load(object sender, EventArgs e)
{
try
{
cnDataCon.Open();
{
loadDdlTitles();
}
}
catch (Exception errDesc)
{
string strMsgError = "Error encountered on open: " + errDesc.Message.ToString().Replace('\'', ' ');
MessageBox.Show(#"<script language='javascript'>alert('" + strMsgError + "')</script>");
MessageBox.Show(#"<script language='javascript'>alert('Application will terminate')</script>");
return;
}
}
private void loadDdlTitles()
{
//Response.Write(#"<script language='javascript'>alert('loadDDlTitles')</script>");
// store sql into a string in order to be utilized at a later time.
string strSqlTitles = "SELECT * FROM tblTitles ORDER BY title";
// data adapters act as data filters
OleDbDataAdapter daTitles = new OleDbDataAdapter();
// command syncs the data source with the filter (data sdapter) and readies it for instantiation
OleDbCommand cmNameTitles = new OleDbCommand(strSqlTitles, cnDataCon);
// select command syncs the filter with the data
daTitles.SelectCommand = cmNameTitles;
try
{
daTitles.Fill(dsData, "tblTitlesInternal"); // blow pt.
}
catch (Exception errDesc)
{
string strMsgError = "Error encountered in data adapter object: " + errDesc.Message.ToString().Replace('\'', ' ');
MessageBox.Show(#"<script language='javascript'>alert('" + strMsgError + "')</script>");
MessageBox.Show(#"<script language='javascript'>alert('Application will terminate')</script>");
}
// Connect control obj to datasource and populate
ddlTitle.DataSource = dsData.Tables["tblTitlesInternal"];
ddlTitle.DisplayMember = "nameTitle";
ddlTitle.ValueMember = "nameTitlesID";
}
}
}
In my App.config i have:
<?xml version="1.0" encoding="utf-8" ?>
<configuration>
<configSections>
</configSections>
<connectionStrings>
<add name="cnExternalData" connectionString="Data Source=|DataDirectory|215-6576.All-Purpose Handyman.dbo; Provider=Microsoft.ACE.OLEDB.12.0" />
<add name="SqlWinApp.Properties.Settings.ConnectionString" connectionString="Data Source=215-6576;User ID=sa"
providerName="System.Data.SqlClient" />
</connectionStrings>
<startup>
<supportedRuntime version="v4.0" sku=".NETFramework,Version=v4.5" />
</startup>
</configuration>
Finally, My database is named 215-6576.All-PurposeHandyman.dbo and the table i am using is named tblTitles. Any help again would be greatly appreciated! Thank you!
An invaluable website I've gone to repeatedly is ConnectionStrings.com.
Assuming everything you already have is correct, you just need to modify your SQL connection string in the config file:
<add name="SqlWinApp.Properties.Settings.ConnectionString" connectionString="Server=215-6576;User ID=sa; Database=All-PurposeHandyman; Password=password"
providerName="System.Data.SqlClient" />
If your sa account has a password, you will need to provide that as well via "Password=[Password]" in that same connectionString attribute.
EDIT
In your C# code, you don't need the braces around your call to loadDdlTitles();, you can safely remove those.
EDIT2
Added password attribute into modified connection string to make clear how it should work.
Well, I see 3 problems just off the bat (and there might be more if I looked more closely). The two that are causing you trouble are:
You're still calling your Access connection string
Your SQL connection string is formatted incorrectly.
The third problem isn't major, but it'll be annoying when you go to fix #1: your connection string name is really long.
Modify your sql connection string thusly:
<add name = "SqlConnection" connectionString="[yourConnectionStringHere]" />
Then modify your calling code:
SqlConnection cnDataCon =
new SqlConnection(ConfigurationManager.ConnectionStrings["SqlConnection"].ConnectionString);
For the specific connection string, I recommend heading to http://connectionstrings.com and taking a look. But it will be something like this:
Server=myServerAddress;Database=myDataBase;User Id=myUsername; Password=myPassword;
You need to have the server/machine name in the connection string. This link has some information and examples to use:
http://msdn.microsoft.com/en-us/library/jj653752%28v=vs.110%29.aspx
I can't seem to be able to access the app.config database connection string in my c# winforms app.
app.config code
<connectionStrings>
<add name="MyDBConnectionString" providerName="System.Data.SqlClient"
connectionString="Data Source=localhost;Initial Catalog=MySQLServerDB; Integrated Security=true" />
</connectionStrings>
C# code:
SqlConnection conn = new SqlConnection();
conn.ConnectionString = System.Configuration.ConfigurationSettings.AppSettings["MyDBConnectionString"];
When I try the C# code, I get a message:
Warning 1 'System.Configuration.ConfigurationSettings.AppSettings' is obsolete: '
This method is obsolete, it has been replaced by System.Configuration!System.Configuration.ConfigurationManager.AppSettings'
However, when I try to use:
conn.ConnectionString = System.Configuration!System.Configuration.ConfigurationManager.AppSettings["MyDBConnectionString"];
I get an error: Only assignment, call, increment, decrement, and new object expressions can be used as a statement
This is all you need:
System.Configuration.ConfigurationManager.ConnectionStrings["MyDBConnectionString"].ConnectionString;
Use ConfigurationManager instead of ConfigurationSettings. It has a ConnectionStrings property that you should use for connection strings in the connectionStrings section:
ConfigurationManager.ConnectionStrings["MyDBConnectionString"].ConnectionString;
You are using the ConnectionStrings collection, not the AppSettings.
ConfigurationManager.ConnectionStrings["MyDbConnectionString"].ConnectionString;
<?xml version="1.0" encoding="utf-8" ?>
<configuration>
<appSettings>
<add key="ConnectionString" value="Data Source=MY-PC;Initial Catalog=DB2013;User ID=sa;Password=MYSQL123" />
</appSettings>
</configuration>
using System.Configuration;
using System.Data.SqlClient;
namespace OnlineDelete_W2013
{
public partial class CommodityEdit : Form
{
SqlConnection MyConnection = new SqlConnection(System.Configuration.ConfigurationSettings.AppSettings["ConnectionString"]);
public CommodityEdit()
{
InitializeComponent();
}
private void button1_Click(object sender, EventArgs e)
{
try
{
MyConnection.Open();
}
catch (Exception)
{
throw;
}
}
}
}
try this
ConfigurationManager.ConnectionStrings["MyDbConnectionString"].ConnectionString;
using (SqlConnection conn = new SqlConnection(System.Configuration.ConfigurationManager.ConnectionStrings["SQLConnection"].ToString()))
{
....(your code here) ...
}
SqlConnection conn = new SqlConnection();
conn.ConnectionString = ConfigurationManager
.ConnectionStrings["MyDBConnectionString"].ConnectionString;
try
{
conn.Open();
}
catch (Exception)
{
throw;
}
The answers stating to use the line
ConfigurationManager.ConnectionStrings["MyDBConnectionString"].ConnectionString;
are correct.
If an error appears stating that ConfigurationManager does not exist, it's because your project hasn't referenced System.Configuration.
To do that in .NET Framework, in Solution Explorer, in the project where you want to use this line of code, right-click in References, choose Add Reference..., then choose Assemblies on the left-side and Framework under it. Pick System.Configuration on the list and click Ok.
About this:
I get an error: Only assignment, call, increment, decrement, and new object expressions can be used as a statement
I just declared a var like this and solved the problem:
var strConnection = System.Configuration.ConfigurationManager.ConnectionStrings["MyDBConnectionString"].ConnectionString;
Please try below code. this is as you are expecting:
SqlConnection MyConnection = new SqlConnection(ConfigurationManager.ConnectionStrings["ConnectionString"].ConnectionString);
The connection name 'MySqlServer' was not found in the applications configuration or the connection string is empty.
So, I have a page with a panel that will display when the connection in the web config is found and the connection is valid; using a try/catch as long as the add name"VALUE" is in the config connection strings if the server data is bad the page will load and the panel is set to invisible... I need to be able to handle the following...
If the named value in this case MySqlServer is used in the aspx; aspx.cs but not found in the config I do not want the error to occur; connection name was not found.... I just want to not show the panel like when the SqlConnection.Open fails when the name is found but data is bad...
aspx
<asp:SqlDataSource runat="server" ID="allowedIPsSqlDataSource"
ConnectionString="<%$ ConnectionStrings:MySqlServer %>"
aspx.cs
string connectionString = ConfigurationManager.ConnectionStrings["MySqlServer"].ToString();
SqlConnection SqlConnection = new SqlConnection(connectionString);
SqlCommand SqlCommand = new SqlCommand();
try
{
SqlConnection.Open();
config
<connectionStrings>
<add name="NotMySqlServer" providerName="System.Data.SqlClient" connectionString="server=TEST\SQL2005;database=ADB;Integrated Security=True"/>
<add name="NotMy2SqlServer" providerName="System.Data.SqlClient" connectionString="server=TEST\SQL2005;database=ADB;Integrated Security=True"/>
</connectionStrings>
You can try :
if(ConfigurationManager.ConnectionStrings["MySqlServer"] == null) throw ...
If you're using .NET 4.5+ and have access to C# 6.0, you can make use of the null conditional operator (?) to try and get the connection string without automatically throwing an exception:
string connectionString = ConfigurationManager.ConnectionStrings["MySqlServer"]?.ConnectionString;
//------------------------------------------------------------------------HERE-^-HERE-------------
if (string.IsNullOrWhiteSpace(connectionString))
{
// Don't even bother trying to open the connection.
// Log the error and either rethrow the exception (throw;) or exit from your current context (return;).
//return;
//throw;
}
// If your code has made it this far, it means you have a valid connection string. Now try to use it.
using (var sqlConnection = new SqlConnection(connectionString))
{
sqlConnection.Open();
using (var sqlCommand = new SqlCommand)
{
// Do stuff.
}
}
You can check if there are any connections strings by using count.
var count = ConfigurationManager.ConnectionStrings.Count;
if (count > 0)
{
//There is at least more then one connection string.
}
Update
public static class Extension
{
public static bool HasConnectionString(this ConnectionStringSettingsCollection value, string key)
{
try
{
return value[key].ConnectionString.Length > 0;
}catch
{
return false;
}
}
}
You can use the extension as follow.
if (ConfigurationManager.ConnectionStrings.HasConnectionString("MySqlServer"))
{
//If true you know there is a valid connectionstring.
}