Passing environment variables to Data Access Layer - c#

Every stored procedure we write has to have clientip, serverip, windows username, etc passed on to it.
The question is how do I efficiently pass these to DAL?

I'm assuming this is a web app in ASP.NET. If that's the case, you have access to all these things in the context of a web request outside of the web application through the following static instance:
System.Web.HttpContext.Current
If everything you need is standard stuff that you usually have in the Request, Response, and User objects that are available by default at the Page level, then this should be all you need. If you need information that is custom to your web app, then Ben's answer (above) should work.

You should have all of the above data accessible either in the System.Environment class, or in your own Thread Principal of some kind. Your DAL can easily pull in from both or either of those sources.

Create a class to hold this data, a factory to build it and helper methods to consume it.
IUserContext
{
int param1 {get;set;}
int param2 {get;set;}
SqlParameter[] GetSqlParameters();
}
UserContext : IUserContext{}
UserContextFactory
{
internal IUserContext IUserContextFromRequest(){}
}
Good luck

Related

How can I dynamically set connection string in MVC 5 based on incoming request?

I have an MVC 5 application that is currently single tenant only, but that is becoming unmanageable as our client-base grows.
I would like to turn this application into a multi-tenant app, accessing a distinct database for each client.
The client's are easily distinguishable by their domain, which I can access through Request.Url.Host or other methods, but once I have this property, I am having trouble setting it in the Business logic project within the context of that request only.
The Business logic project is referenced by the main Web project, but that project is blink to the Request object, so I do not know how to get that session information dynamically each time the baseDataAccess (which contains the connection strings) object is instantiated.
I've spent many many hours on this, and have tried using Ninject to resolve the dependency with no success. I just can't seem to figure out how to get the dynamic Request object or any of its properties to assign transiently to the baseDataAccess object.
The last thing I tried was using and IActionFilter using the OnActionExecuting method, but I am still unable to figure out how to set the value of the URL for each request dynamically in a project that has no context for the current request.
This is the class I want to set dynamically. the _connectionString is the dynamic property. I have methods to build the connection string based on the url, so if I can set the _domain property dynamically and transiently I'll be able to get the connection string.
public class baseDataAccess : IDataAccess
{
private static IClientConnection _clientConnection;
private static string _connectionString;
public static string _domain;
...
This is the last attempt I made, adding the OnActionExecuting method to each controller. How can I set these properties dynamically and transiently?
public void OnActionExecuting(ActionExecutedContext filterContext)
{
IClientConnection client = new ClientConnectionFactory(Request.Url.Host);
IDataAccess dataAccess = new baseDataAccess(client);
}
I'm have the same need for my application. I have to set the connection String with the user information depending on the user login. I added a reference on System.Web to get the Session object in my business layer.
The main idea is, to store the current user in the Session and let the business logic access this Session with HttpContext.Current.Session now my database classes can read the connection string dynamically on every single access to the database.
And as the user session is available in any library that has the System.Web reference, it can be used application wide. So there is no problem setting the connection string on the Session_Start event depending on the request from the user.

Unity Dependency Injection - How to create the instance to be injected at runtime

Trying to implement Dependency Injection in an ASP.Net Web API project.
I would like to be able to inject an instance of Account into some of my services.
The Account instance should be created with the users Guid and this is not known until runtime.
So in my service I have:
public TransactionService(Account acc)
{
_account = acc;
}
And in my application startup I can do this - where container is a new UnityContainer:
container.RegisterType<Instanet.Engine.Account>(new InjectionConstructor(new Guid("xxxxxx")));
This, of course, isn't any good as it would be using the same Account for every user/request etc.
If I try to use something like :
container.RegisterType<Instanet.Engine.Account>(new InjectionConstructor(GetTheUsersID()));
... where GetTheUsersID() needs to either examine a cookie or the ASP.Net Identity request it's of course not available in the app startup.
So - Where/How (in simple terms please, this DI stuff is hurting my brain) do I implement this so I can inject an instanced Account into any of the services that may need it.
You generally don't want to mix state and behavior for components that get resolved via the container--DI should be used for components that can be modeled as pure services.
That said, sometimes it makes sense to wrap global or context-specific state in a service component.
In your case, if you only need the UserId locally in a one or more services (in other words, not passing it from one service to another). You mentioned being able to get the UserId from a cookie, so maybe it would look something like:
public class CookieService : ICookieService
{
public int GetCurrentUserId()
{
//pseudo code
return HttpContext.Current.GetCookie["UserId"];
}
}
Now you can inject ICookieService where a UserId is needed.
More complex cases may require an Abstract Factory:
http://blog.ploeh.dk/2012/03/15/ImplementinganAbstractFactory/
If there is only one Account instance possible for the session, then I would create an Account instance in the bootstrap code before all your services are running.
Then you can populate the guid and all other data in your account instance, and register the initialized instance of Account class in Unity via container.RegisterInstance method.
Later it will resolve to what you need.
Does it help?

access Auth() object from TryAuthenticate

I am logging into my service from a c# client like so:
serviceClient.Send<ServiceStack.ServiceInterface.Auth.AuthResponse>(
new ServiceStack.ServiceInterface.Auth.Auth() {
UserName = "xxx",
Password = "yyy" }
);
I would now like to use one of the unused strings in the Auth class to pass some additional information (like a programid). I am using my own subclassed CredentialsAuthProvider. Two questions:
Do you recommend any of the "extra" properties in the Auth class to stuff my programid over any others? I was considering using "State", will that mess anything up if I put a string in there?
Is there a way from within the TryAuthenticate override of my CredentialsAuthProvider to access the Auth class instance that was sent to me (so I can access the programid that I stuck into the State property).
Thank you.
Answered half of my question.
Not sure if any of the properties are better than any other, but I'm using "State" to stuff some extra data. Now that multiple end user programs are accessing the same service, sending a program ID in the State property lets me log the programs attempting to log into the service, along with the users.
If you are authenticating by overriding CredentialsAuthProvider, you can override the Authenticate method to gain access to the Authenticate object that is passed in from the user. From there, you can read the State property (or any other).

Access session in class library.

I am developing an application architecture that uses 2 sub projects:
a) asp.net web application (it covers user interface and business logic) and
b) class library. (it covers data access layer)
After system user successfully logs in , the user information is stored in a session object.
The problem I am facing is when I try to access that session object in class library project(data access layer), it always returns null.
I need to access the session object in class library project because, in my case each user has their own username and password for database access(for security reasons);
So, How how do i read and write from/to session object in class library project
Use the System.Web.HttpContext.Current.Session object.
First of all, as Peri correctly noticed - you need to think again if having separate database logins for each user is a good idea - because you loose connection pooling (different users won't be able to reuse existing connections - and creating a new sql connection is quite expensive).
If you really wish to keep separate database users, I would create interface to abstract session from data access:
public interface ILoginDataService
{
LoginData Current { get; }
}
And implementation would pass login data from session. In such way you won't have session dependency to session in your data access logic - so it will be more testable, also you'll separate concerns.
Here is the code I used within a library to get session information.
public static string Entity()
{
string entity = "";
HttpContext httpContext = HttpContext.Current;
if (httpContext.ApplicationInstance.Session.Count > 0)
entity = httpContext.ApplicationInstance.Session["EntityCode"].ToString();
return entity;
}
I am having an ASP.Net application which uses session. I am able to access it in my app_code files using [WebMethod(EnableSession = true)] for the function. I am not sure whether this is your problem. I also faced session value as null when I removed (EnableSession = true) on the method.
using System.Web;
namespace ClassNameSpace
{
public class Class1 : IRequiresSessionState
{
private string sessionValue => HttpContext.Current.Session["sessionKey"].ToString();
}
}

MVC Routes - How to get a URL?

In my current project we have a notification system. When an oject is added to another objects collection, an email is sent to those who are subscibed to the parent object. This happens on the object layer and not in the View or Controller.
Here's the problem:
Although we can say who created what with what information in the email, we cannot embed links to those objects in the email because in the object layer there is no access to a UrlHelper. To construct a UrlHelper you need a RequestContext, which again does not exist on the object layer.
Question:
I want to make a helper class to create the url's for me. How can I create an object that will generate these urls without a request context? Is it possible?
The problem is compounded by the fact that you don't want a relative URL in an email, you want an absolute email so you need to hard-code the domain too because there is no request to grab it from.
Another factor is that emails can outlive the current site structure by months or years so you need a kind of permalink, and thus a way to associate multiple Urls with a single action (additional routes). This latter issue is also a factor in SEO where you don't want to leave any page behind.
For now a static method on your controller UrlToActionX(params) sitting next to the method ActionX seems like the simplest workaround. All it does is the appropriate string.Format(...) on the id's of the strongly-typed parameters to generate the permanent Url. Add a static domain on the front, or a domain from the user object (since you know which domain they visit when they come to your site) and you have your email link.
It's not ideal but at least you now have only one place to maintain the Url generation.
IMHO: When it comes to permanent links to a changing web site sometimes it's better to rely on "configuration over convention". :-)
I'm not aware of a way to do this, you MUST have access to the routes at the very least to make your own helper. Unless your business objects know about the registered routes, you can't get away from doing some hard-coding.
Here is how you might limit the hard-coding of urls though...
Code in a url with all the relevant bits in your object's methods..
class Event
{
public void SendEmail()
{
var url = string.Format("http://myurl.com/r/Event?eventId={0}", EventId);
//send emails...
}
}
Note the /r/Event piece of the url. This would be a map to a RController that would be responsible for taking arbitrary, made-up links and sending a 301 Permanent Redirect and going through the route engine to create a real url using the current routes. This way you are only hard-coding a utility controller url and not to the ever evolving controller actions of your real pages.
class RController : Controller
{
public ActionResult Event(int eventId)
{
Response.StatusCode = (int)HttpStatusCode.MovedPermanently;
Response.RedirectLocation = Url.Action("Details", "Event", new { eventId = eventId });
return null;
}
public ActionResult Register(int eventId)
{
Response.StatusCode = (int)HttpStatusCode.MovedPermanently;
Response.RedirectLocation = Url.Action("Register", "Event", new { eventId = eventId });
return null;
}
}
It just feels a bit better than hard-coding a bunch of different controllers/actions that you might decide to rename later. Think of it as your own little TinyUrl like service.
You could define an interface with a method that takes whatever information is necessary to create a URL (object ids or whatever) and returns a URL. Write an implementation of that interface that uses the UrlHelper to do this work, and then supply this to your object layer (ideally with an IoC container).
You could use:
VirtualPathUtility.ToAbsolute(string.Format("~/r/Event?eventId={0}", id))
to resolve the url. Still not nice though.

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