Is it possible to use Servicestack ORMLite in a C# Class library?
I have been searching the internet but cant find any example where the data layer is used in a class library
Sure, there's nothing special about a class library, you'll just need to pass in an open ADO.NET IDbConnection or an IDbConnectionFactory and you can use OrmLites extension methods as normal. A class library would also only need a reference to the ServiceStack.OrmLite NuGet package, I.e. Doesn't require a reference to any concrete RDBMS provider.
Related
i wanna know if it's possible to inject dependency for a class constructor as it is injected for controllers, i have the following cenario as an example:
An AccountController which depends on an AccountRepository like bellow:
public AccountController(IAccountRepository repository)
The dependency is injected perfectly using Unity DI, which have the following configuration:
container.RegisterType<IUserStore<ApplicationUser>, UserStore<ApplicationUser>>(new HierarchicalLifetimeManager(), accountInjectionConstructor);
container.RegisterType<UserManager<ApplicationUser>>(new HierarchicalLifetimeManager());
container.RegisterType<IdentityDbContext<ApplicationUser>, ApplicationDbContext>(new HierarchicalLifetimeManager());
The problem is that i have a class AuthorizationServiceProvider which also needs the AccountRepository... In this case, how would i instantiate or use this AuthorizationServiceProvider class without having to instantiate and provide it all the dependencies?
Provider = new SimpleAuthorizationServerProvider>(),
This provider is set inside the Startup class and called before the Unity DI config initializes...
Here the visual studio complains that there's no argument given that corresponds to the class constructor, but if i provide a new AccountRepository i'd have to provide all it's dependencies as well, (ApplicationDbContext context, UserManager userManager) which are already provided for the Unity DI when creating the controllers....
Could somebody help me please?
Thanks in advance...
how would i instantiate or use this AuthorizationServiceProvider class without having to instantiate and provide it all the dependencies?
You can't. This is actually the core of what we're trying to achieve with Dependency Injection. Your application code should let go of the control over its dependencies. This means that your application code should not create an AuthorizationServiceProvider. Rather, it should let a third-party provide this dependency. Typically, this means you require the dependency be supplied using Constructor Injection.
Letting application code create these dependencies itself causes problems, typically referred to as the Control Freak anti-pattern or Dependency Inversion Principle violation. It causes strong coupling, which can hinder maintainability.
When working with Dependency Injection, this third-party is called the Composition Root. The Composition Root is:
a (preferably) unique location in an application where modules are composed together.
With DI, only the Composition Root will create graphs of objects. You are using Unity, which is a DI Container. The DI Container acts as the Composer, which is part of your Composition Root.
Instead of using a DI Container, you can build the object graphs by hand, which means you will have to create a complete tree of dependencies at once. This practice is called Pure DI. Still, the Composition Root is the location where those object graphs are created; with or without a DI Container.
Your view of DI might be troubled by the use of the standard Identity template that Visual Studio provides. From a design and DI perspective, however, this template is horrifying.
Either way, all these stated concepts, patterns and anti-patterns are described quite thoroughly in the book Dependency Injection in .NET by Mark Seemann.
I have one project with multiple libraries. The problem I have is that I can’t access some libraries from others, as when I add a reference I get an error about circular dependencies. I assume I need to create an interface but I am not really sure how to structure it. Here is an example of what I have:
My references are setup like this:
WebApp (This is an ASP.Net web site) - Has Reference to BusinessLayer Class Library and Utilities Class Library
Data Class Library (This library provides abstract database functionality) - has no references
BusinessLayer Class Library (provides a business logic layer) - has references to Data Class Library, DataLayer Class Library, and Utilities Class Library
DataLayer Class Library (provides a layer that directly interfaces with the database i.e. CRUD commands) - has references Data Class Library and Utilities Class Library
Utilities Class Library (general library that are used across all layers) - has no references
For the most part this is fine. But, I have a class in the Utilities Class Library that needs to reference functions and properties in the WebApp and BusinessLayer Class Libraries. I cannot add a reference to these projects, as that would create a circular dependency. So, how would I go about setting up the Interface and the correct references?
The way you have designed your application is very similar to architecture pattern defined
here
As for your utility class, you can define an interface in BusinessLayer/domain layer and implement that interface in utility layer. Please note it should only return types defined in business layer/domain. This way you will get a nice separation of concerns. If let's say your web needs to consume this utility method, you can apply transformation to convert your domain type into web project specific type. This way you won't run into circular dependency.
I created a sample application based on these principles, you can refer to my github
project.
It sounds like you need to move those common functions out of webapp and into your utilities library. I don't think you should be referencing your web app from any of your other libraries.
LINQ to SQL Connection Strings with class library projects
By default, creating a new LINQ to SQL model (.dbml) will put the
connection strings in both the application settings file and also
web.config / app.config. This is not so much of a problem for web
projects, but what about class library projects? i have a connection
class where I can use it to check connection in all pages but I have an
error where it cant read DataContext at all.
This is a photo that shows my problem.
Generally speaking, class libraries don't support config files. There are ways to make it work, but it's not considered a good practice since different applications may use the same library to interact with different instances of the database. I would recommend looking at a dependency injection or inversion of control solution like Ninject to pass the connection string to the constructor from the app that references the library.
UPDATE:
If you absolutely must read a config file from an assembly instead of the calling application, it can be done with ConfigurationManager.OpenExeConfiguration(). There are several answers here on SO that provide code samples for doing so, but I'm not going to link to them because I strongly encourage you not to go down that road.
By the looks of it you're not using LINQ to SQL - all I can see is an EntityFramework edmx. Check your code generation strategy, and make sure you're trying to instantiate the correct context name (think it's whatever the Entity Container Name is set to).
Also you need to make sure System.Configuration is referenced.
You need to put the connection strings in the main application app.config
Just put a copy of the connection strings in there and you can access them or in this case web.config
I have a class that needs a custom JsonConverter to properly be deserialized. It is a value object (in DDD terminology), and I need to include it in a message being sent with NServiceBus when using Json serialization.
The problem is, since NServiceBus internalizes their copy of Json.Net, I have to use the JsonConverter base class that is included in NSB, but it has been marked "internal" during the merge.
This basically prevents you from hooking any custom serialization code into NSB. Is this by design? Is there a recommended workaround?
If you are having problems with the merged assemblies you can find the core only assemblies on the downloads page on github.
I'm using the .NET 4 framework, and I have a static class with static functions in an asp.net web application.
I have a second class library project. The class library project wants to call the static method in the web application. Intellisense works, but then the compiler reports that
"The name [MyClassName] does not exist in the current context".
Can I make this call, or this not allowed?
PS, the static class is in the /App_Code folder.
Thanks!
Is it not possible to refactor the class out of the web project? Referencing a web project from a class library sounds awkward. If your class does not contain web-specific code then you could pop it into that other class library you mention or create a new one. Should it reference web-specific libraries something like MyProject.MyLib.Web could do the trick.
You need to add a reference to the project containing the class you want to access.
You need to ensure that you are using the full name of the class (including the namespace).
Alternatively add a using directive with the namespace to your code file.
If your target framework is .Net Framework 4.0 Client Profile change it to .NET Framework 4 and rebuild the solution.