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GetSchema("Databases") on ODBC connection (C#)

I am testing various DB connection methods in C#. In particular, I am testing SqlConnection and OdbcConnection classes; my DB is SQLServer Express (.\SQLEXPRESS). Both are working reasonably well, except in listing available databases on the server.
In my test code I use a "generic" DbConnection object and a simple factory to create an instance of specific SqlConnetion and OdbcConnetion subclasses (they both derive from DbConnection):
DbConnection connection;
switch (connection_type)
{
case DbConnectionType.DBCONN_MSSQL:
connection = new SqlConnection(...sql connection string...);
break;
case DbConnectionType.DBCONN_ODBC:
connection = new OdbcConnection(...odbc connection string...);
break;
}
The trick seems to work well except when I try to get the list of databases on the server:
DataTable databases = connection.GetSchema("Databases");
foreach (DataRow database in databases.Rows)
{
String databaseName = database["database_name"] as String;
Console.WriteLine(databaseName);
}
When "connection" is an OdbcConnection (and, note, the database is the same), I get an exception saying that "Databases" key was not found. I listed all the keys exposed by GetSchema(), and the ODBC version returns only a subset of the items exposed by the SQLServer version. I couldn't find any hint about this specific problem. Is it a documented/expected behaviour? Am I doing something wrong?
NOTE: here how I build the ODBC connection string:
OdbcConnectionStringBuilder builder;
builder = new OdbcConnectionStringBuilder();
builder.Driver = "SQL Server";
builder.Add("Server", ".\\SQLEXPRESS");
builder.Add("Uid", "");
builder.Add("Pwd", ""); // Using current user
builder.Add("Integrated Security", "SSPI");
connection = new OdbcConnection(builder.ConnectionString);

Is it a documented/expected behaviour?
Yes. See Retrieving Database Schema Information
Am I doing something wrong?
If your goal is to read SQL Server metadata in a provider-agnostic way, then yes. You should query the SQL Server catalog views directly. sys.databases, sys.tables, etc.

Make sure your "Databases" model has a valid Key. Add the [Key] Data annotation if the key you want to implement for that database doesn't follow the "ClassName"+"ID" entity framework rule.

Entity Framework: The context is being used in Code First mode with code that was generated from an EDMX file

I am developing an WPF application with EF 6 database first approach, I am have 1 project in my solutions, if i run my project this error always appear.
The context is being used in Code First mode with code that was generated from an EDMX file for either Database First or Model First development. This will not work correctly. To fix this problem do not remove the line of code that throws this exception. If you wish to use Database First or Model First, then make sure that the Entity Framework connection string is included in the app.config or web.config of the start-up project. If you are creating your own DbConnection, then make sure that it is an EntityConnection and not some other type of DbConnection, and that you pass it to one of the base DbContext constructors that take a DbConnection. To learn more about Code First, Database First, and Model First see the Entity Framework documentation here: http://go.microsoft.com/fwlink/?LinkId=394715

My mistake was using standard connection string in constructor
(Server = test\test; Database = DB; User Id = test_user;Password = test),
but Entity Framework needs different format
(metadata=res://*/DBModel.csdl|res://*/DBModel.ssdl|res://*/DBModel.msl;provider=System.Data.SqlClient;provider connection string="data source=test\test;initial catalog=DB;integrated security=True;MultipleActiveResultSets=True;App=EntityFramework""" providerName = ""System.Data.EntityClient)
Edit: Changed code to be formatted as code so it's easier to read.

EF makes assumptions based on the presence or absence of a metadata section in the connection string. If you receive this error you can add the metadata section to the connection string in your config file.
E.g. if your connection string looks like this:
<add name="MyModel" connectionString="data source=SERVER\INSTANCE;initial catalog=MyModel;integrated security=True;MultipleActiveResultSets=True;App=EntityFramework" providerName="System.Data.SqlClient" />
Prepend metadata=res://*/MyModel.csdl|res://*/MyModel.ssdl|res://*/MyModel.msl; so that it looks like this:
<add name="MyModel" connectionString="metadata=res://*/MyModel.csdl|res://*/MyModel.ssdl|res://*/MyModel.msl;data source=SERVER\INSTANCE;initial catalog=MyModel;integrated security=True;MultipleActiveResultSets=True;App=EntityFramework" providerName="System.Data.SqlClient" />

One thing you can do is... (if is Database first)
Open the .edmx[Diagram] -> right click -> "Update Model from database"
And see if the will appear the "Add", "Refresh" and "Delete" tabs.
If doesn't... probably your connection is broken and the dialog for VS creates a new connection string will appear instead. =)

You shouldnt use generated connection string, now you have all metadata files included in your solution. Instead try use in connection string section of app.config:
"data source=localhost\sqlexpress; initial catalog=sample; integrated security=True;MultipleActiveResultSets=True;"

None of the above solutions worked for me. But I did find the SqlConnectionBuilder class here which did work: https://learn.microsoft.com/en-us/dotnet/api/system.data.entityclient.entityconnectionstringbuilder?view=netframework-4.8
Its the same as specifying the string as some of the other suggestions here but it builds the string for you.
// Specify the provider name, server and database.
string providerName = "System.Data.SqlClient";
string serverName = ".";
string databaseName = "AdventureWorks";
// Initialize the connection string builder for the
// underlying provider.
SqlConnectionStringBuilder sqlBuilder =
new SqlConnectionStringBuilder();
// Set the properties for the data source.
sqlBuilder.DataSource = serverName;
sqlBuilder.InitialCatalog = databaseName;
sqlBuilder.IntegratedSecurity = true;
// Build the SqlConnection connection string.
string providerString = sqlBuilder.ToString();
// Initialize the EntityConnectionStringBuilder.
EntityConnectionStringBuilder entityBuilder =
new EntityConnectionStringBuilder();
//Set the provider name.
entityBuilder.Provider = providerName;
// Set the provider-specific connection string.
entityBuilder.ProviderConnectionString = providerString;
// Set the Metadata location.
entityBuilder.Metadata = #"res://*/AdventureWorksModel.csdl|
res://*/AdventureWorksModel.ssdl|
res://*/AdventureWorksModel.msl";
Console.WriteLine(entityBuilder.ToString());
using (EntityConnection conn =
new EntityConnection(entityBuilder.ToString()))
{
conn.Open();
Console.WriteLine("Just testing the connection.");
conn.Close();
}

I also faced this exact same message, but workig with a web MVC project. This message is fired when I try to auto generate the Controller from the imported model. It seems that it is not working because "that was generated from an EDMX file".
The good news is that it works if I generate the model based in the "Code First" instead of "EF Designer". The bad news is that I can't use the EF Designer if I want that the automatically controller generation works. Does not matter which from those two ways you generates your model. Once the model is generated, you use it in the same way.
Tries to remove all your emdx objects from your project and recreate the model based in the Code First instead of EF Designer. Worked for me!

Very much late but still helpful. I got stuck in a similar problem. Posted a question about on SO and was able to find a solution. You can refer to Connection String errors in C# Web Api.
My situation was I had two connection strings in web.config (you'll get to know why when go to the link). Commenting one string was raising the error you got while commenting the other one was raising error as below:
An error occurred when trying to create a controller of type 'AccountController'. Make sure that the controller has a parameterless public constructor.
what i did was: I named my first connection string as DefaultConnection and in ApplicationDbContext class constructor I gave this DefaultConnection. Now my AccountController uses this connection string and all other controllers use second connection string.
This solved my problem.

I have two projects:
One is for the generated EDMX file and all related models.
The other one is the ASP.NET MVC Web.
I encountered this issue since the connection string that I am using on the ASP.NET MVC Web project is the normal string that I use using ADO.NET connection. So what I did is the following:
Open the app.config on your EDMX project files.
Copy its connection string.
Paste it on the WEB project since this will be used when you start
the application.

DbMigrator does not detect pending migrations after switching database

EntityFramework migrations become useless after switching to new Context.
DbMigrator is using list of Pending Migrations from first database instance, which makes means no migrations are applied to other databases, which then leads to errors during Seed();
C# .NET 4.5 MVC project with EF 6
MS SQL Server 2014, multiple instances of same database model.
CodeFirst approach with migrations.
DbContext initializer is set to null.
On Application Start we have custom Db Initialization to create and update databases. CreateDatabaseIfNotExists is working as intended, new databases have all migrations applied. However both MigrateDatabaseToLatestVersion initializer and our custom one are failing to update databases other than first one on list.
foreach (var connectionString in connectionStrings)
{
using (var context = new ApplicationDbContext(connectionString))
{
//Create database
var created = context.Database.CreateIfNotExists();
var conf = new Workshop.Migrations.Configuration();
var migrator = new DbMigrator(conf);
migrator.Update();
//initial values
conf.RunSeed(context);
}
}
context.Database.CreateIfNotExists(); works correctly.
migrator.GetLocalMigrations() is always returning correct values.
migrator.GetPendingMigrations() after first database is returning
empty list.
migrator.GetDatabaseMigrations() is mirror of pending migrations,
after first database it contains full list event for empty databases.
Fetching data (context.xxx.ToList()) from Db instance confirms connection is up and working, and links to correct instance.
Forcing update to most recent migration with migrator.Update("migration_name"); changes nothing. From what I gather by reading EF source code, it checks pending migration list on its own, which gives it faulty results.
There seems to be some caching going in under the hood, but it eludes me how to reset it.
Is there a way to perform migrations on multiple databases or is it yet another "bug by design" in EF?
Edit:
Real problem is DbMigrator creating new Context for its own use. It does it via default parameterless constructor, which in my case had fallback to default (first) connection string in web.Config.
I do not see good solution for this problem but primitive workaround in my case is to temporarily edit default connection string:
var originalConStr = WebConfigurationManager.ConnectionStrings["ApplicationDbContext"].ConnectionString;
var setting = WebConfigurationManager.ConnectionStrings["ApplicationDbContext"];
var fi = typeof(ConfigurationElement).GetField("_bReadOnly", BindingFlags.Instance | BindingFlags.NonPublic);
//disable readonly flag on field
fi.SetValue(setting, false);
setting.ConnectionString = temporaryConnectionString; //now it works
//DO STUFF
setting.ConnectionString = originalConStr; //revert changes
Cheat from: How do I set a connection string config programatically in .net?
I still hope someone will find real solution so for now I will refrain with self-answer.

You need to correctly set DbMigrationsConfiguration.TargetDatabase property, otherwise the migrator will use the default connection info.
So in theory you can do something like this
conf.TargetDatabase = new System.Data.Entity.Infrastructure.DbConnectionInfo(...);
Unfortunately the only 2 public constructors of the DbConnectionInfo are
public DbConnectionInfo(string connectionName)
connectionName: The name of the connection string in the application configuration.
and
public DbConnectionInfo(string connectionString, string providerInvariantName)
connectionString: The connection string to use for the connection.
providerInvariantName: The name of the provider to use for the connection. Use 'System.Data.SqlClient' for SQL Server.
I see you have the connection string, but have no idea how you can get the providerInvariantName.
UPDATE: I didn't find a good "official" way of taking the needed information, so I've ended using a hack with accessing internal members via reflection, but still IMO it's a quite more safer than what you have used:
var internalContext = context.GetType().GetProperty("InternalContext", BindingFlags.Instance | BindingFlags.NonPublic).GetValue(context);
var providerName = (string)internalContext.GetType().GetProperty("ProviderName").GetValue(internalContext);
var conf = new Workshop.Migrations.Configuration();
conf.TargetDatabase = new System.Data.Entity.Infrastructure.DbConnectionInfo(connectionString, providerName);

Error passing existing connections to DbContext constructor when using Database-First

I'm trying to create a class to perform work on the database and have the need (or preference) to use a combination of DbContext and good old fashioned ADO. Why, well EF is great for simplifying a great deal of code but ADO still has many uses for more complex methods that EF cannot yet handle.
This link on MSDN states that I can pass an existing SqlConnection to my context as follows:
using (var conn = new SqlConnection("..."))
{
conn.Open();
using (var context = new SampleContext(conn, contextOwnsConnection: false))
{
// Do Something
}
}
Now I'm using Database-First so this constructor doesn't appear as standard. I therefore created a new Partial Class file and created the appropriate constructor as follows:
public partial class MyEntities : DbContext
{
public MyEntities(System.Data.Common.DbConnection conn, bool contextOwnsConnection = false)
: base(existingConnection: conn, contextOwnsConnection: contextOwnsConnection)
{
}
}
However, when I run the code the moment it hits a call to the new DbContext constructor, I get the following UnintentionalCodeFirstException() error thrown by OnModelCreating in my EDMX file:
"Code generated using the T4 templates for Database First and Model First development may not work correctly if used in Code First mode. To continue using Database First or Model First ensure that the Entity Framework connection string is specified in the config file of executing application. To use these classes, that were generated from Database First or Model First, with Code First add any additional configuration using attributes or the DbModelBuilder API and then remove the code that throws this exception."
Am I missing something obvious here, or can it just not be done with Database-First?
Clearly, I could just use two connections, one for my SqlConnection object, and another for my DbContext object but if I can, naturally I'd prefer to use a single connection if possible.
Any and all help greatly appreciated. For full disclosure, I'm using SQL-Server 2012, .NET 4.5.1, C# and EF6.0.2.

Connection strings used by the designer are not regular connection strings. Rather they are EntityConnection strings. The difference is that entity connection strings contain additional information about where to find metadata describing the model which is in form of the edmx at design time - read more here. Code First uses just regular connection strings since it builds the model on the fly based on the code. So, the UnintentionalCodeFirstException is preventing the user from using CodeFirst functionality with edmx models because the model is specified in the edmx and not in the code and if it was allowed you would effectively end up using two different models (one from edmx and one built from the code) which very likely won't be in sync which would result in weird behavior or even could lead to data corruption and crashes/exceptions.
Since the EntityConnection is derived from DbConnection and just wraps regular connection you can use it in places where you would use the provider connection. Alternatively you can access the wrapped provider connection using the StoreConnection provider on the EntityConnection.

I know this is an old thread, but later versions of Entity Framework actually can handle a shared connection, so I offer this as an alternative answer.
You can initialize an instance of the entity container with a shared connection. Use the EntityConnection(MetadataWorkspace workspace, DbConnection connection, bool entityConnectionOwnsStoreConnection) overload and specify false for the entityConnectionOwnsStoreConnection parameter. Then pass it into your context constructor as the existing connection. The EntityConnection will then prevent the connection from being automatically closed and disposed with the context.
Example:
using (var conn = new SqlConnection("..."))
{
conn.Open();
// Execute some ADO queries.
var md = new MetadataWorkspace(new[]{"res://*/SampleModel.csdl","res://*/SampleModel.ssdl","res://*/SampleModel.msl"}, new[]{System.Reflection.Assembly.GetExecutingAssembly()});
// Create the EntityConnection so the existing connection is not disposed.
var ec = new EntityConnection(md, conn, false);
using (var context = new SampleContext(conn, contextOwnsConnection: false))
{
// Do something using the entity context.
}
// Entity context is disposed but connection remains open.
// Do more ADO stuff.
}
Yes, it was a pain to figure out this stuff by examining System.Data and Entity Framework source code.
This pattern may be used within a TransactionScope to prevent escalation to a distributed transaction by virtue of using the same database connection.

Add a connection string to local user config file throws lock exception

I have developed a WinForm C# app that use ADO.NET Entity Framework for storing data.
I would like each user to have a database stored in their appdata\local folder but when I try to add the connection string to the users local app.config file I constantly get the error "ConfigurationSection properties cannot be edited when locked."
After I did some research I discovered the allowExeDefinition section setting.
I tried adding this setting for the connectionString section in the app.config file and at runtime (see code below) but I still get the same error whenever I try to save the configuration.
This is the code I use:
var connectionString = string.Format(ConnectionStringBase, dbLocation);
var exeConf = ConfigurationManager
.OpenExeConfiguration(ConfigurationUserLevel.PerUserRoamingAndLocal);
var connectionStringSettings =
new ConnectionStringSettings(
"DatabaseEntities",
connectionString,
ProviderName);
exeConf.ConnectionStrings
.SectionInformation
.AllowExeDefinition = ConfigurationAllowExeDefinition.MachineToLocalUser;
exeConf.ConnectionStrings.ConnectionStrings.Add(connectionStringSettings);
exeConf.Save(ConfigurationSaveMode.Minimal);
I have tried to search for a solution for this issue for days but I haven't been able to find anything usefull besides that I am considering storing the connection string in the users settings instead as a workaround but it feels kinda hackish.

Alright, instead of updating the app.config file I decided to create the connectionstring on runtime and pass it to the entity set constructor.
So when I initialize the entity set I use the following code instead:
var connectionString = string.Format(ConnectionStringBase, dbLocation);
var entities = new DatabaseEntities(connectionString);
The only thing to note is that if the connection string contains " you should replace these with single quotes ( ' ).