We Keep Coding

DB2 Connection string with SSL Server Certificate on .NET (Core)

I have been attempting to set up a DB2 Connection programmatically, via .NET, and I've puzzled with the following findings:
1. Testing a connection on VS Code
After installing the Db2 Connect extension, I've populated the following fields:
Database Name;
Host;
Port;
UserID;
Password;
and set the Checkbox Enable SSL Security = true, in addition to populating the full path of the SSL Server Certificated (saved on my local drive C:\...crt).
As a result, the Db2 connection has been established.
2. Testing a connection programmatically
After adding IBM.Data.DB2.Core as a reference into the project through NuGet, I've used in a Controller:
using System;
using IBM.Data.DB2.Core;
namespace SSLTest
{
class Program
{
static void Main()
{
DB2Command MyDB2Command = null;
String MyDb2ConnectionString = "database=alias;uid=userid;pwd=password;"; // nub of
//the issue
DB2Connection MyDb2Connection = new DB2Connection(MyDb2ConnectionString);
MyDb2Connection.Open();
MyDB2Command = MyDb2Connection.CreateCommand();
MyDB2Command.CommandText = "SELECT * from d.Test";
...
MyDb2DataReader.Close();
MyDB2Command.Dispose();
MyDb2Connection.Close();
}
}
}
To fully replicate programmatically the connection settings described in 1., I've used:
String MyDb2ConnectionString = "DATABASE=xxxxx;SERVER=xxxxx;UID=xxxx;PWD=xxxx;Security=SSL";
where SERVER = Hostand wonder on the way to add the SSL Server pathinto the connection string. Otherwise the connection would keep failing.
Thanks in advance.
Best

How to set a EF code first connection string at runtime

I'm missing something. I have a small project where I am trying to insert some data into a database. When I created the model I used Code First against an existing database. I wanted to make the app capable of point to any server at runtime. This is a down and dirty utility app an and running internally but I need some flexibility when running it.
From reading some msdn articles I saw where I could extend the DBContext on initialization so I did the following:
added a parameter to the initialization:
public OtherEventModel(string ConnectionString)
: base("name=OtherEventModel")
{...
Then within my code I built the connection string based upon the properties passed in from the UI:
private OtherEventModel ConnectToServer(string server, string username, string password)
{
try
{
SqlConnectionStringBuilder sqlBuilder = new SqlConnectionStringBuilder
{
DataSource = server,
UserID = username,
Password = password,
InitialCatalog = "My_Database",
IntegratedSecurity = true
};
var connection = sqlBuilder.ToString();
ModelContext = new OtherEventModel(connection);
return ModelContext;
}
catch (Exception ex)
{
throw new Exception(string.Format("Error connecting to server {0}", ex.Message));
}
I can see the connection string created however when I run the code I receive an exception that the connection string (what should be in app.config could not be found). Which I do not have a connection string or key within app config since I was trying to inject the connection string in at runtime.
Error:
Error inserting data No connection string named 'OtherEventModel' could be found in the application config file
I was under the impression from what I have read that Code first uses a standard SQL connection string and does not require the EntityConnectionStringBuild (used for object first dev)
Can someone point me in the right direction as to what I have missed or what I am doing wrong.
Thanks in advance

You're almost there, just pass the connection string to the base:
public OtherEventModel(string ConnectionString)
: base(ConnectionString)
Make sure you comment the throw line in the method below. Unfortunately you have to do this again every time you update the model.

Connecting to connectionString in app.config

I have my connection string stored in App.Config
<connectionStrings>
<clear />
<add name="CTaC_Information_System.Properties.Settings.CIS_beConn"
connectionString="Provider=Microsoft.ACE.OLEDB.12.0;Data Source="\\server\file\CIS Data\Database\CIS_be.accdb&quote;;Jet OLEDB:Database Password=123"
providerName="System.Data.OleDb" />
Then when I go to my main.xaml.cs I type in the following:
string cisconn = ConfigurationManager.ConnectionStrings["CTaC_Information_System.Properties.Settings.CIS_beConn"].ConnectionString;`
I found that answer on Stack Overflow when searching, but some were say to put var but when I typed var it wouldn't recognize it so I went with the string method.
When I go to type cisconn.Open(); the option isn't there. I am referencing System.Configuartion;,System.Data.Sql; System.Data.SqlClient; and System.Data.OleDb;.
Can someone show / tell me how I can connect to the database from c#? I'm trying to test the connection when my application runs but I can't figure it out.

The connection string is just a string, its meant to be used in your connection, so you should do:
public void DoSomeDatabaseOp()
{
string cisconn = ConfigurationManager.ConnectionStrings["CTaC_Information_System.Properties.Settings.CIS_beConn"].ConnectionString;
using (OleDbConnection conn = new OleDbConnection(cisconn))
{
conn.Open();
//Create your commands or do your SQL here.
}
}
You should create/destroy the connection inside the method you are using it in. Don't keep a reference to it in the root of the class object. This keeps the connections clean and open if you aren't doing database operations.
If you really wanted to though, you could do this:
class MyClass
{
OleDbConnection _rootConn;
string _connStr;
public MyClass()
{
_connStr = string cisconn = ConfigurationManager.ConnectionStrings["CTaC_Information_System.Properties.Settings.CIS_beConn"].ConnectionString;
_rootConn = new OleDbConnection(_connStr);
}
public void DoSomeDatabaseOp()
{
//Use _rootConn here
}
}
BUT the class should implement IDisposable so that it can dispose of the connection properly! How to implement IDisposable is beyond the scope of the answer, but look up how to implement it properly.

Connecting to localDb in a unit test throws exception

I have a VS2013 project that talks to a Sql Server database, using EF6.1. To date, I've been running some automated tests using the Effort in-memory database.
I'm experimenting with using Sql Server's LocalDb, instead, and I'm running into problems I don't understand.
From with VS's Server Explorer, I created a new connection to a LocalDb database, and through it I created a new database, then
I brought up the properties window on the database, in Server Explorer, and copied the Connecting String to my clipboard, then
I pasted this connection string into the ConnectionString element of my test assembly's App.config,
I ran one of the tests.
I get:
System.ArgumentException: "Keyword not supported: 'data source'".
My connection string is simple:
<add name="MyDbContext"
connectionString="Data Source=(localdb)\v11.0;Initial Catalog=localDb;Integrated Security=True"
providerName="System.Data.EntityClient"
/>
And my code is equally simple:
[TestClass]
public class TestCustomers
{
private MyDbContext myDbContext = null;
private IEnumerable<customer> defaultCustomers = new []
{
new customer{customerid = "Customer 1"},
new customer{customerid = "Customer 2"},
new customer{customerid = "Customer 3"},
};
[TestInitialize]
public void init()
{
this.myDbContext = new MyDbContext();
foreach (var customer in this.defaultCustomers)
this.myDbContext.customers.Add(customer);
this.myDbContext.SaveChanges();
}
[TestMethod]
public void testAllCustomers()
{
var customers = this.myDbContext.customers;
var customerList = customers.ToList();
Assert.IsTrue(customerList.Count == 3);
}
}
Any ideas as to what might be going wrong?

You have specified the provider as System.Data.EntityClient instead of System.Data.SqlClient. Both of those require different connection string formats.
A good source for working out what to use is http://www.connectionstrings.com

Change Database during runtime in Entity Framework, without changing the Connection

I have a server that hosts 50 databases with identical schemas, and I want to start using Entity Framework in our next version.
I don't need a new connection for each of those databases. The privileges of the one connection can talk to all of the 50 databases, and for data management and speed (this is a WebAPI application) I don't want to instantiate a new EF context every time I talk to each of the databases if I don't have to, unless of course if this occurs each time a request comes to the server then no big deal.
All I really need is the ability to change the USE [databasename] command, which I assume eventually gets sent to the server from EF.
Is there a way to accomplish this in code? Does EF maintain a read/write property in the Context that refers to the database name that could be changed on the fly before calling SaveChanges(), etc.??
Thank you!!!
bob

Don't Work hard, work smart !!!!
MYContext localhostContext = new MYContext();
MYContext LiveContext = new MYContext();
//If your databases in different servers
LiveContext.Database.Connection.ConnectionString = LiveContext.Database.Connection.ConnectionString.Replace("localhost", "Live");
//If your databases have different Names
LiveContext.Database.Connection.ConnectionString = LiveContext.Database.Connection.ConnectionString.Replace("DBName-Localhost", "DBName-Live");
the structure for databases should be the same ;)

You can take a look at:
SO question about passing existing SQL Connection to
EntityFramework Context
and at this article describing how to
change database on existing connection.
Please let me know if any additional help is needed.
Edited
Updated 2nd link to point to SqlConnection.ChangeDatabase method.
So eventually code would look similarly to the following:
MetadataWorkspace workspace = new MetadataWorkspace(
new string[] { "res://*/" },
new Assembly[] { Assembly.GetExecutingAssembly() });
using (SqlConnection sqlConnection = new SqlConnection(connectionString))
using (EntityConnection entityConnection = new EntityConnection(workspace, sqlConnection))
using (NorthwindEntities context = new NorthwindEntities(entityConnection))
{
// do whatever on default database
foreach (var product in context.Products)
{
Console.WriteLine(product.ProductName);
}
// switch database
sqlConnection.ChangeDatabase("Northwind");
Console.WriteLine("Database: {0}", connection.Database);
}

It is very simple
I had
public WMSEntities() : base("name=WMSEntities") //WMSEntities is conection string name in web.config also the name of EntityFramework
{
}
already in autogenerated Model.Context.cs of edmx folder.
To connect to multiple database in runtime, I created another constructor that takes connection string as parameter like below in same file Model.Context.cs
public WMSEntities(string connStringName)
: base("name=" + connStringName)
{
}
Now, I added other connection string in Web.Config for example
<add name="WMSEntities31" connectionString="data source=TESTDBSERVER_NAME;initial catalog=TESTDB;userid=TestUser;password=TestUserPW/>
<add name="WMSEntities" connectionString="data source=TESTDBSERVER_NAME12;initial catalog=TESTDB12;userid=TestUser12;password=TestUserPW12/>
Then, when connecting to database I call below method passing connectionString name as parameter
public static List<v_POVendor> GetPOVendorList(string connectionStringName)
{
using (WMSEntities db = new WMSEntities(connectionStringName))
{
vendorList = db.v_POVendor.ToList();
}
}

Here's my solution for just changing the database name. Simply pull the string from the web or app.config file, modify it, and then instantiate:
string yourConnection = ConfigurationManager.ConnectionStrings["MyEntities"].ConnectionString.Replace("MyDatabase", yourDatabaseName);
dcon = new MyEntities(yourConnection);

I have implemented this in my current project in which we have a common security database and different database for every client in the project. So our security database has a table that contain connection string for every other database. We just pass client id and get the connection string of the client database..
For this add two EDMX one for the common database and other for common schema databases. When user login or what might be your scenario to choose database go to common databse and get the connection string and create object of the needed database. Here is Code sample any, if any quer let me know..
You can keep connection string regarding every other database in a table in a a common database shared by all the other database.
EntityInstance_ReviewEntities.GetContext(GetConnectionString(ClientId));
private string GetConnectionString(int TenantId)
{
EntityConnectionStringBuilder entityBuilder = new EntityConnectionStringBuilder();
ISecurityRepository objSecurity = new SecurityRepository();
string tenantConnectionString = objSecurity.GetClientConnectionString(TenantId);
entityBuilder.ProviderConnectionString = tenantConnectionString;
entityBuilder.Provider = "System.Data.SqlClient";
entityBuilder.Metadata = #"res://*/ClientEntity.YourEntity.csdl|res://*/ClientEntity.ADBClientEntity.ssdl|res://*/ClientEntity.YourEntity.msl";
return entityBuilder.ToString();
}

EntityConnection.ChangeDatabase method is not supported, but SqlConnection.ChangeDatabase works fine.
So you have to use SqlConnection in entity framework database's constructor:
using MvcMyDefaultDatabase.Models;
using System.Data.Metadata.Edm;
using System.Data.SqlClient;
using System.Data.EntityClient;
using System.Configuration;
using System.Reflection;
public ActionResult List(string Schema)
{
SqlConnection sqlConnection = new SqlConnection(ConfigurationManager.ConnectionStrings["MyConnectionString"].ConnectionString);
MetadataWorkspace workspace = new MetadataWorkspace(new string[] { "res://*/" }, new Assembly[] { Assembly.GetExecutingAssembly() });
EntityConnection entityConnection = new EntityConnection(workspace, sqlConnection);
sqlConnection.Open();
sqlConnection.ChangeDatabase(Schema);
Models.MyEntities db = new MyEntities(entityConnection);
List<MyTableRecords> MyTableRecordsList = db.MyTableRecords.ToList();
return View(MyTableRecordsList);
}
With this code you can read the tables with the same format (same table name and same fields) of several schema passing the database name in the "Schema" string.

For SQL Server, if you want to change only the database, not a connection, try:
public class XXXXDbContext : DbContext
{
public string databaseName
{
set
{
Database.GetDbConnection().Open();
Database.GetDbConnection().ChangeDatabase(value);
}
}
}