I'm using .Net core 2.2 and it's dependency injection. I also inject dependencies from third party libraries. I want to deep clone the object where dependencies are injected. Binary Serialization is not an option as classes from other libraries are not marked as Serializable. Json serialization and Reflection cloning is not working as many classes do not have default constructors.
I looked at this, this and this but not helping
How should I deep clone objects?
Not sure if this is related to exactly what you're issue may be, but I had same issue and it was due to how I was bringing in the DbContexts in the startup.cs file. I had to remove the LazyLoading for the connection that I was using trying to make the DeepClone. Once I did that, it went back to working as expected.
FROM:
services.AddDbContext(options =>
options.UseSqlServer(Configuration.GetConnectionString("DbMaster"), opt => opt.UseRowNumberForPaging())
.EnableSensitiveDataLogging().UseLazyLoadingProxies());
TO:
services.AddDbContext(options =>
options.UseSqlServer(Configuration.GetConnectionString("DbMaster"), opt => opt.UseRowNumberForPaging()).EnableSensitiveDataLogging());
Hope that can help.
Related
I'm trying to find how I can use dependency injection to inject a ConnectionString or a custom AppSetting object so far i end up in the startup using
services.Configure<IConnectionStrings>(Configuration.GetSection("MyConnection"));
example layer
Web MVC application
Business Logic (class library)
Repository (class library)
DAL (class library)
Model (class library)
where web see only Business logic and so on, on model is available for all.
In the DAL project I have an object that takes care of connecting and running queries against my database (CDbTools object).
Now, how can I inject directly into CDbTools without going from controller down to DAL.
Thank you.
Dependency injection definitely takes a little getting used to, and you won't be creating objects quite the way you're used to. What you want to do is first is modify your CDbTools to take the injected strings.
public CDbTools(IConnectionStrings strings)
{
_connectionString = strings
}
The next step will be to actually inject the CDbTools into the classes that need it as well. First, register it in the startup.
services.AddScoped<CDbTools>();
You'll need to follow this up the chain. Don't think of it as passing the objects from the top level down - that will mess up your separation of concerns. Each layer has the lower layer injected in. This won't just get you the injection of your string you are looking for. It will let you mock things easier, swap layers easier, and a slew of other benefits.
I believe you should add this to your ConfigureServices method:
services.Configure<CustomSettings>(settings =>
{
Configuration.GetSection("CustomSettings").Bind(settings);
});
Where services is your IServiceCollection object and CustomSettings is your custom configuration class that you want to inject. That custom object should map to your settings fields.
Hope this helps!
I am in the process of transitioning my 'regular' Backbone projects into a combination of Backbone and RequireJS. While this process works pretty flawless, I still have one question.
Previously I declared a global namespace for my app to which I then bound all my models, views an collections. This is a tip I actually got from the Backbone ToDoMVC project.
So for example, the initialize method of a view could look like this:
initialize: function () {
app.employees = new app.EmployeeCollection();
app.employees.fetch();
}
This works because at the beginning of every file, I've done this:
var app = app || {};
Now when defining my files as AMD modules, the app namespace doesn't exist anymore, which means everything is much more encapsulated:
initialize: function () {
var employees = new EmployeeCollection();
employees.fetch();
}
The EmployeeCollection is loaded with RequireJS:
var EmployeeCollection = require('collections/EmployeeCollection');
Unfortunately I am still very new to Backbone and MVC in general, so I am unsure if this is a good or a bad thing.
What impact will this have on my project – is it okay to use an app namespace like I did previously or does this break any MVC/OOP 'rule'? Are there any Backbone specific consequences I need to be aware of?
Yes, loading the EmployeeCollection via requirejs is a good thing. This explicitly lists each module's dependencies and lets requirejs help you with loading modules in the proper order.
Both the app namespace approach and the requirejs approach are both valid. Backbone won't care which approach you take since with either you have the necessary View/Collection/Model constructor available to use. Personally I like the above benefits I mentioned of requirejs but it's a personal preference you'll have to decide.
However, you shouldn't use requirejs and an all-knowing app namespace together. If you're committed to requirejs then you should only use the app namespace sparingly with top-level data that most of your app will need, rather than attaching all of your requirejs modules to it.
For example, you might use it for a global UserModel that contains information about the current user. To do this you'd create an app object as a requirejs module just like you did with your EmployeeCollection, and then whatever module constructs the UserModel would require 'app' and do a simple assignment: app.user=user.
I said do this sparingly because using a global app namespaces for all your modules would sacrifice much of the benefit of requirejs and would cause you some sequencing pain. Namely:
You can no longer see the actual dependencies for each module declaratively and visualize easily how all your modules fit together. Instead of having the initialize function of your view (or whatever that is) require in 'collections/EmployeeCollection' you'd be requiring 'app'; not a lot of context there.
Requirejs will take care of loading required modules first before allowing your defining function to run. But if everything just requires 'app' then requirejs will only ensure 'app' is defined first and you're on your own for everything else. If app.Bar requires app.Foo, you have to do something to make sure app.Foo gets loaded and defined first.
On a similar note, if requirejs can't figure out all your dependencies because everything just requires 'app' then requirejs's javascript concatenator and optimizer tool (called r.js) will be either useless to you or require a lot of maintenance to add all your modules to a list that it should compile.
If you decide to use requirejs, embrace what it can do for you and just require in the modules you want instead of relying heavily on a global namespace. But there's not a right or wrong way choosing between these two approaches; each is used by lots of smart people.
I'm having a frustrating issue with Ninject and MVC 4.
Here is the code block:
Kernel.Bind<IUserInfo>().To<UserInfo().InRequestScope();
var userInfo = Kernel.Get<IUserInfo>();
Most of the time, this is fine, and I have a user info. Sometimes, though, I get the following error:
Error activating IUserInfo
No matching bindings are available, and the Type is not self-bindable.
Activation path:
1) Request for IUserInfo
Suggestions:
1) Ensure that you have defined a binding for IUserInfo.
2) If the binding was defined in a module, ensure that the module has been loaded into the kernel.
3) Ensure you have not accidentally created more than one kernel.
4) If you are using constructor arguments, ensure that the parameter name matches the constructors parameter name.\r\n 5) If you are using automatic module loading, ensure the search path and filters are correct.
I've pared down everything I cant think to, and am at a loss. I don't know why this would fail intermittently. Based on my admittedly limited knowledge of Ninject, there should be no way for the binding to be missing.
I see a lot of references to using the Ninject MVC Nuget packages, but the app as I inherited it does not use those, it initializes Ninject using an ActionFilter. Is this pattern just broken at its core, and somehow interfering with proper binding?
Help?
Take a look at the BindFilter option
https://github.com/ninject/ninject.web.mvc/wiki/Filter-configurations
There is some sort of caching issue I believe, that makes filters behave differently to controllers. This means that the binding can fail, usually under heavy load, but unpredicatably.
It turns out that newer versions of Ninject need more setup for InRequestScope to work. By removing Ninject entirely, and readding references to Ninject, Ninject.Web.Common, and Ninject.Web.MVC, it added the Ninject.Web.Common.cs file that was neccessary for InRequestScope to work.
Previously, it was actually binding InTransientScope, which meant it would get garbage collected, which is non-deterministic, which explains my intermittent issues. I wish it would have thrown exceptions when i tried to bind InRequestScope, but c'est la vie.
I have been playing around the last couple of days with different solutions for mapping DTO's to entities for a VS2013, EF6, WCF Service App project.
It is a fairly large project that is currently undergoing a major refactoring to bring the legacy code under test (as well as port the ORM from OpenAccess to EF6).
To be honest I had never used AutoMapper before but what I saw I really liked so I set out to test it out in a demo app and to be honest I am a bit ashamed that I have been unable to achieve a working solution after hours of tinkering and Googling. Here is a breakdown of the project:
WCF Service Application template based project (.svc file w/code behind).
Using Unity 3.x for my IoC container and thus creating my own ServiceHostFactory inheriting from UnityServiceHostFactory.
Using current AutoMapper nuget package.
DTO's and DAL are in two separate libraries as expected, both of which are referenced by the service app project.
My goal is simple (I think): Wire up and create all of my maps in my composition root and inject the necessary objects (using my DI container) into the class that has domain knowledge of the DTO's and a reference to my DAL library. Anyone that needs a transformation would therefore only need to reference the transformation library.
The problem: Well, there are a couple of them...
1) I cannot find a working example of AutoMapper in Unity anywhere. The code snippet that is referenced many times across the web for registering AutoMapper in Unity (see below) references a Configuration class that doesn't seem to exist anymore and I cannot find any documentation on its deprecation:
container.RegisterType<AutoMapper.Configuration, AutoMapper.Configuration>(new PerThreadLifetimeManager(), new InjectionConstructor(typeof(ITypeMapFactory),
AutoMapper.Mappers.MapperRegistry.AllMappers())).RegisterType<ITypeMapFactory,
TypeMapFactoy>().RegisterType<IConfiguration, AutoMapper.Configuration>().RegisterType<IConfigurationProvider,
AutoMapper.Configuration>().RegisterType<IMappingEngine, MappingEngine>();
2) Where to create the maps themselves... I would assuming that I could perform this operation right in my ServiceHostFactory but is that the correct place? There is a Bootstrapper project out there but I have not gone down that road (yet) and would like to avoid it if possible.
3) Other than the obviously necessary reference to AutoMapper in the DTO lib, what would I be injecting into the instantition, the configuration object (assuming IConfiguration or IConfigurationProvider) and which class I am injecting into the constructor of the WCF service to gain access to the necessary object.
I know #3 is a little vague but since I cannot get AutoMapper bound in my Unity container, I cannot test/trial/error to figure out the other issues.
Any pointers would be greatly appreciated.
UPDATE
So I now have a working solution that is testing correctly but would still like to get confirmation that I am following any established best practices.
First off, the Unity container registration for AutoMapper (as of 11/13/2013) v3.x looks like this:
container
.RegisterType<ConfigurationStore, ConfigurationStore>
(
new ContainerControlledLifetimeManager()
, new InjectionConstructor(typeof(ITypeMapFactory)
, MapperRegistry.AllMappers())
)
.RegisterType<IConfigurationProvider, ConfigurationStore>()
.RegisterType<IConfiguration, ConfigurationStore>()
.RegisterType<IMappingEngine, MappingEngine>()
.RegisterType<ITypeMapFactory, TypeMapFactory>();
Right after all of my container registrations, I created and am calling a RegisterMaps() method inside of ConfigureContainer(). I created a test mapping that does both an auto mapping for like named properties as well as a custom mapping. I did this in my demo app for two reasons primarily:
I don't yet know AutoMapper in a WCF app hosted in IIS and injected with Unity well enough to fully understand its behavior. I do not seem to have to inject any kind of configuration object into my library that does the transformations and I am still reading through the source to understand its implementation.
As I understand it, there is a caching mechanism at play here and that if a mapping is not found in cache that it will create it on the fly. While this is great in theory, the only way I could then test my mappings that were occurring in my composition root was to do some sort of custom mapping and then call Mapper.Map in the library that performs mapping and returns the DTO.
All of that blathering aside, here is what I was able to accomplish.
WCF Service App (composition root) injects all of the necessary objects including my DtoConversionMapper instance.
The project is made up of the WCF Service App (comp root), DtoLib, DalLib, ContractsLib (interfaces).
In my ServiceFactoryHost I am able to create mappings, including custom mappings (i.e. map unlike named properties between my DTO and EF 6 entity).
The DtoConversionMapper class lives in the DtoLib library and looks like this: IExampleDto GetExampleDto(ExampleEntity entity);
Any library with a reference to the DtoLib can convert back and forth, including the Service App where the vast majority of these calls will take place.
Any guiding advice would be greatly appreciated but I do have a working demo now that I can test things out with while I work through this large refactoring.
Final Update
I changed the demo project just a little by adding another library (MappingLib) and moved all of my DTO conversions and mappings to it in a static method. While I still call the static method in my composition root after the Unity container is initialized, this gives me the added flexibility of being able to call that same map creation method in my NUnit unit test libraries, effectively eliminating any duplication of code surrounding auto mapper and makes it very testable.
I am currently experiencing a problem in my RCP application and wanted to ask, if someone stumbled over the same problem and can give me some valuable hints:
My RCP application allows plugins to provide implementations of a specific abstract class of my model (singleton) to extend my model during runtime via the update manager. I instantiate these classes via
extensionPointImplementation.createExecutableExtension(..)
after parsing the Eclipse registry. I can serialize the created instances using the default Java serialization API.
Now to the problem: The plugin trying to deserialize the objects cannot find the class implementations of the model extensions due to the fact, that there is no plugin dependency between the plugins. Nevertheless, it is not possible for me to create such a dependency which would make the idea of extending the model during runtime obsolete.
Is it possible to solve this problem by using the default Java serialization API or do I have to implement my own serialization (which parses the Eclipse registry and creates the instances via the line shown above if all necessary plugins are available, otherwise throw an exception) which might be based on the default Java serialization API (if possible I do not want to create the serialization completely by myself)?
Thanks.
You need to define a so called buddy policy.
In the bundle trying to instantiate the class add
Eclipse-BuddyPolicy: registered
to the manifest.mf.
In the bundle providing the class add
Eclipse-RegisterBuddy: <symbolic name of the bundle instantiating the class>
to the manifest.mf.