Develop Reference

Can You Use Variables This Way

This is my syntax, but it is not being passed to my connection string, it is being omitted, which of course is causing an error as the database doesn't exist. Is it possible to do this?
namespace bottomsup
{
class onetwothree
{
private static string databaseName = null;
private static string ServerConnectionString = "Data Source=BradJohnson;Initial Catalog=" + databaseName + "DB;User ID = pmartin;Integrated Security=True;MultipleActiveResultSets=True"";
Form1()
{
InitializeComponents();
}
private void ConnectToServerClick()
{
databaseName = textbox1.Text;
using (SqlConnection connection = new SqlConnection(ServerConnectionString))
{
connection.Open();
//more stuff
}
}
}
}

No, if you change the value of databaseName later on, it doesn't automatically change the value of ServerConnectionString.
You have to set the value of ServerConnectionString again yourself.
ServerConnectionString =
string.Format("Data Source=BradJohnson;Initial Catalog={0}DB;User ID = pmartin;Integrated Security=True;MultipleActiveResultSets=True", textbox1.Text);
I'd avoid the static variable, as it can lead to bugs if you try to reuse it, and especially if you overwrite it, in multiple places. One place sets it, then another, and now one or the other is going to grab an incorrect value when it tries to retrieve it.
Perhaps something like this instead, where you always have to pass the database name in:
private static string GetServerConnectionString(string databaseName)
{
return string.Format("Data Source=BradJohnson;Initial Catalog={0}DB;User ID = pmartin;Integrated Security=True;MultipleActiveResultSets=True", databaseName);
}
To use it with your existing code:
using (var connection = new SqlConnection(GetServerConnectionString(textbox1.Text)))
{
connection.Open();
//more stuff
}

I doubt if statics are justified in this case.
Nevertheless, it will not work with variable ServerConnectionString, but you could use a property instead:
private static string ServerConnectionString
{
get
{
return "Data Source=BradJohnson;Initial Catalog=" + databaseName +
"DB;User ID = pmartin;Integrated Security=True;MultipleActiveResultSets=True";
}
}

Often when you try to add a null value to something which has a value, it will fall over. In the DB Name you should use String.Empty as opposed to null.
Also I think you have an extra quote on the end of the string.
When you set the connection string, it is not going to dynamically update if you ever change the other property anyway.

Modify connectionString in WCF Data Services 5.6

I'm using Oracle DataAccess (the last one), I have many Database users inside it. So, I want to create the connectionString in my client application (WPF) and pass it to the server. I'm doing the following in my server:
protected override POSContext CreateDataSource()
{
HttpRequest req = HttpContext.Current.Request;
if (req.Headers != null && Array.FindIndex(req.Headers.AllKeys, c=>c.Equals("db", StringComparison.OrdinalIgnoreCase)) > 0)
{
string database = req.Headers["db"];
string user = req.Headers["user"];
string pass = req.Headers["pass"];
StringBuilder conexion = new StringBuilder();
conexion.Append("DATA SOURCE=");
conexion.Append(database);
conexion.Append(";USER ID=");
conexion.Append(user);
conexion.Append(";PASSWORD=");
conexion.Append(pass);
if (!string.IsNullOrEmpty(conexion.ToString()))
return new POSContext(conexion.ToString());
}
return null;//new POSContext();
}
In the client, I have the following code:
var context = new POS.DataServices.POSContext(new Uri(Storage.Current.UrlService)); // Something like this http://localhost/POService.svc
context.BuildingRequest += (s, args) => //Or SendingRequest2 produces the same result
{
args.Headers.Add("db", Storage.Current.Configuraciones.DB);
args.Headers.Add("user", Storage.Current.Configuraciones.UserName);
args.Headers.Add("pass", Storage.Current.Configuraciones.Password);
};
MessageBox.Show(proxy.POS_CIUDAD.ToList().FirstOrDefault().CIU_DESC); //Alert the city name
When I debug my application I have an error (request error). My client code is trying to Show the message first and then go to the BuildingRequest. How can I pass the connectionString before Entity calls?

CreateDataSource is called once when the service starts, that's why you get the error there.
I think you can try the following:
Add a connection string a property on POSContext, and give POSContext a parameterless constructor. That is the connection string could be set later. And maybe you need to make sure the connection is only set when the connection string is ready.
Override OnStartProcessingRequest method, and change the connection string on CurrentDataSource (POSContext class)

HOW TO: dynamic connection string for entity framework

Like the title. How can I do it?
I tried something, but it doesn't work like I was expecting.
I'm using an Entity Framework model. I need to pass my connection string like parameter, so, in another file, I've written
namespace MyNamespace.Model
{
using System;
using System.Data.Entity;
using System.Data.Entity.Infrastructure;
public partial class MyEntities: DbContext
{
public MyEntities(string nameOrConnectionString) : base(nameOrConnectionString)
{
}
}
}
When I startup the app, I call this constructor in this way, so I can refer to this from anyway in the app:
public static MyEntities dbContext = new MyEntities(mdlImpostazioni.SetConnectionString());
where mdlImpostazioni.SetConnectionString() returns a string (the data are correct):
server=192.168.1.100\SVILUPPO;database=MyDB;uid=myName;pwd=111111;
When I execute this code, it seems to be all ok, but when I try to make a query like:
var query = (from r in MainWindow.dbContext.TabTipoSistema select r);
it throws an exception from here:
protected override void OnModelCreating(DbModelBuilder modelBuilder)
{
throw new UnintentionalCodeFirstException(); //exception here
}
So, this is a bad way... which is the right one? (using only code C#, not from xaml)

Your approach is correct, but you need to remember the connection string for EF requires the metadata and so on. So use the EntityConnectionStringBuilder. For example:
// the model name in the app.config connection string (any model name - Model1?)
private static string GetConnectionString(string model, YourSettings settings)
{
// Build the provider connection string with configurable settings
var providerSB = new SqlConnectionStringBuilder
{
// You can also pass the sql connection string as a parameter instead of settings
InitialCatalog = settings.InitialCatalog,
DataSource = settings.DataSource,
UserID = settings.User,
Password = settings.Password
};
var efConnection = new EntityConnectionStringBuilder();
// or the config file based connection without provider connection string
// var efConnection = new EntityConnectionStringBuilder(#"metadata=res://*/model1.csdl|res://*/model1.ssdl|res://*/model1.msl;provider=System.Data.SqlClient;");
efConnection.Provider = "System.Data.SqlClient";
efConnection.ProviderConnectionString = providerSB.ConnectionString;
// based on whether you choose to supply the app.config connection string to the constructor
efConnection.Metadata = string.Format("res://*/Model.{0}.csdl|res://*/Model.{0}.ssdl|res://*/Model.{0}.msl", model); ;
return efConnection.ToString();
}
// Or just pass the connection string
private static string GetConnectionString(string model, string providerConnectionString)
{
var efConnection = new EntityConnectionStringBuilder();
// or the config file based connection without provider connection string
// var efConnection = new EntityConnectionStringBuilder(#"metadata=res://*/model1.csdl|res://*/model1.ssdl|res://*/model1.msl;provider=System.Data.SqlClient;");
efConnection.Provider = "System.Data.SqlClient";
efConnection.ProviderConnectionString = providerConnectionString;
// based on whether you choose to supply the app.config connection string to the constructor
efConnection.Metadata = string.Format("res://*/Model.{0}.csdl|res://*/Model.{0}.ssdl|res://*/Model.{0}.msl", model);
// Make sure the "res://*/..." matches what's already in your config file.
return efConnection.ToString();
}
EDIT
The exception you get is because when you pass a pure SQL connection string, it assumes you are working with Code first, so it calls the OnModelCreation event. When you include the MetaData section as shown above, that tells EF it's a complete EF connection string.

I believe the problem lies on the Datasource you specify. You need to add the port of the connection, e.g if your SQL Server is configured on Port 1433, try:
server=192.168.1.100,1433\SVILUPPO;database=MyDB;uid=myName;pwd=111111;
more details about connection strings you can find Here
Also I am not sure if uid and pwd are valid, better try User ID and Password:
Server=192.168.1.100,1433\SVILUPPO;Database=MyDB;User ID=myName;Password=111111;
Finally mind the case sensitivity.

How to in-code supply the password to a connection string in an ADO.Net Entity Data Model

I've been following this tutorial on how to create an OData service.
http://www.hanselman.com/blog/CreatingAnODataAPIForStackOverflowIncludingXMLAndJSONIn30Minutes.aspx
And it works flawlessly ... but, in the Entity Data Model Wizard, when it asks you to "Choose Your Data Connection" it gives you this warning.
"This connection string appears to contain sensitive data (for example, a password) that is required to connect to the database. Storing sensitive data in the connection string can be a security risk. Do you want to include this sensitive data in the connection string?"
If I choose: "No, exclude sensitive data from the connection string. I will set it in my application code."
I do not see where I can, "in my application code" insert the password. (My company stores them encrypted in the registry)
Plus, I have multiple DBs that I need to connect to, depending on the environment (Dev, CA, or Prod) and I need to know what DB is referenced in the connection string to get the correct password.
Thanks.

When you create your context, you can set a connection string. To build this connection string, you can parse the connection string without the password with an EntityConnectionStringBuilder and then parse the inner connection string with an other ConnectionStringBuilder, depending on your browser. Then you can set the password and pass it to the constructor.
var originalConnectionString = ConfigurationManager.ConnectionStrings["your_connection_string"].ConnectionString;
var entityBuilder = new EntityConnectionStringBuilder(originalConnectionString);
var factory = DbProviderFactories.GetFactory(entityBuilder.Provider);
var providerBuilder = factory.CreateConnectionStringBuilder();
providerBuilder.ConnectionString = entityBuilder.ProviderConnectionString;
providerBuilder.Add("Password", "Password123");
entityBuilder.ProviderConnectionString = providerBuilder.ToString();
using (var context = new YourContext(entityBuilder.ToString()))
{
// TODO
}

I added a "dummy" password in the configuration file ("XXXXX"), then replaced that value with the real password in the entity constructor
public MyDatabaseContainer() : base("name=MyDatabaseContainer")
{
Database.Connection.ConnectionString = Database.Connection.ConnectionString.Replace("XXXXX","realpwd");
}

Modify the constructor of the entities
public sampleDBEntities() : base("name=sampleDBEntities")
{
this.Database.Connection.ConnectionString = #"Data Source=.\;Initial Catalog=sampleDB;Persist Security Info=True;User ID=sa;Password=Password123"; ;
}

My sample application was written in "Database First" mode and the "CreateNewConnectionString" method below works just fine (though it doesn't look all that elegant.)
The "CreateNewConnectionString2" method looks really elegant, BUT causes an exception telling me it's only valid in "Code First" mode.
So I'm providing both methods along with the constructor I modified to use my methods. NOTE AND BEWARE, I've modified code generated by a template and that is subject to being overwritten if the code is regenerated. To me it seems like the right place to put it.
If your application was generated in "Code First" mode, you may need to use "CreateNewConnectionString2" (I have not yet tested this option.)
I hasten to admit that I copied both code blocs from other postings as I don't yet know nearly enough about all this to write my own code.
private static string CreateNewConnectionString(string connectionName, string password)
{
var config = System.Web.Configuration.WebConfigurationManager.OpenWebConfiguration("~").ConnectionStrings.ConnectionStrings[connectionName];
//or:
//var config = ConfigurationManager.ConnectionStrings[connectionName];
var split = config.ConnectionString.Split(Convert.ToChar(";"));
var sb = new System.Text.StringBuilder();
for (var i = 0; i <= (split.Length - 1); i++)
{
if (split[i].ToLower().Contains("user id"))
{
split[i] += ";Password=" + password;
}
if (i < (split.Length - 1))
{
sb.AppendFormat("{0};", split[i]);
}
else
{
sb.Append(split[i]);
}
}
return sb.ToString();
}
private static string CreateNewConnectionString2(string connectionName, string password)
{
var originalConnectionString = ConfigurationManager.ConnectionStrings[connectionName].ConnectionString;
var entityBuilder = new EntityConnectionStringBuilder(originalConnectionString);
var factory = DbProviderFactories.GetFactory(entityBuilder.Provider);
var providerBuilder = factory.CreateConnectionStringBuilder();
providerBuilder.ConnectionString = entityBuilder.ProviderConnectionString;
providerBuilder.Add("Password", password);
entityBuilder.ProviderConnectionString = providerBuilder.ToString();
return entityBuilder.ProviderConnectionString;
}
public ChineseStudyEntities()
: base(CreateNewConnectionString("ChineseStudyEntities", "put YOUR password here")) // base("name=ChineseStudyEntities")
{
}

LINQ to SQL connectionstring

I have an application that I want to be able to configure the connection string for my LINQ to SQL. I've tried so many different ways but cannot seem to get it working. I want to do this dynamically in the code when the app is run, the reason for this is that the user can change the connection settings.
If I delete the connectionString out of app.config the application still works OK (communicating) which makes me wonder where I should be changing the connection string?

I think that the best way to do it is a combination of Albin's and Rup's answers. Have a value in the config file, and then read it at run time and feed it to the context constructor, something like this:
WEB.CONFIG:
<appSettings>
<add key="ConString" Value="The connection string" />
CODE:
//read value from config
var DBConnString = System.Configuration.ConfigurationManager.AppSettings("ConString");
//open connection
var dataContext= new MyDataContext(sDBConnString)
this way you can change the connection string even at runtime and it will work and change on the running program.

You can pass an override connection string into the DataContext constructor:
var db = new MyDataContext("Data Source=Something Else;")

The DBML class (YourDataContext) has an overloaded constructor which takes ConnectionString, so try instantiating that instead of the default one.Get the connection string from app.config and use that to create the instance.
YourDataContext context = new YourDataContext (ConfigurationManager.ConnectionStrings["ConnStringInAppConfig"].ConnectionString)

You should change it in app.config. The reason it works without is that the LINQ2SQL designer creates a fallback to the connection string used when designing the DBML. If you define a connection string in app.config that is used instead.

By Default your constructor look like this
public dbDataContext() :
base(global::invdb.Properties.Settings.Default.Enventory_4_0ConnectionString, mappingSource)
{
OnCreated();
}
You can change return value Instead of
//Original
public string Enventory_4_0ConnectionString {
get {
return ((string)(this["Enventory_4_0ConnectionString"]));
}
}
this
//Modified code
public string Enventory_4_0ConnectionString {
get {
return (System.Configuration.ConfigurationManager.ConnectionStrings["Enventory_4_0ConnectionString"].ConnectionString);
}
}

Inside your dbml file designer.cs add this dynamic call to base class constructor. It will work for local, dev and prod automatically pulling from current web.config without need to pass connection every time;
public HallLockerDataContext() :
base(ConfigurationManager.ConnectionStrings["MYDB1"].ConnectionString, mappingSource)
{
OnCreated();
}
Usage:
using (var db = new HallLockerDataContext())
{
}