Example: I have a countries catalog stored in another DB and I need to use it as a property in some ContentParts. I'm trying to make the connection without interfering much with Orchard wiring.
public class MoviePart : ContentPart<MoviePartRecord>
{
public IEnumerable<CountryRecord> Countries
{
get
{
return Record.Countries.Select(r => r.CountryRecord);
}
}
}
The relation between CountryRecords and MovieParts will be on the Orchard DB, but the CountryRecord data is in another DB. I only need Read access, but I don't get which and how to override the Handler to use the other source.
Do I need to create a ContentHandler and override all methods, and create another StorageFilter that uses the new repository with the external source? And how would I inject the new repo into the handler?
public class CountryPartHandler : ContentHandler
{
public CountryPartHandler(IRepository<CountryPartRecord> repository)
{
Filters.Add(StorageFilter.For(repository));
}
protected override void Loading(LoadContentContext context)
{
base.Loading(context);
}
}
Update:
In this Using External Data with Orchard (around 25th min) video, he seems to be doing what I need with this code:
public ProductPartHandler(IRepository<ProductPartRecord> repository, Work<IProductService> productServiceWork)
{
Filters.Add(StorageFilter.For(repository));
OnActivated<ProductPart>((context, part) => {
part.ProductField.Loader(() => productServiceWork.Value.GetProduct(part.Id));
});
}
But in my code it can't find the "Loader" function, even though I have all the references from the video too, so maybe ProductField is a custom type?
So that is a lazy field on the part, something like this:
public class MyPart : ContentPart {
internal readonly LazyField<CustomData> CustomDataField = new LazyField<CustomData>();
public CustomData CustomData {
get { return CustomDataField.Value; }
}
}
public class CustomData {
...
}
public class MyPartHandler : ContentPartHandler {
private ICustomService _customService;
public MyPartHandler(ICustomService customService){
_customService = customService;
OnActivated<MyPart>(Initialize);
}
private void Initialize(ActivatedContentContext context, MyPart part){
part.CustomDataField.Loader(() => {
return _customService.Get(part.ContentItem.Id);
});
}
}
I don't know how you are loading your external data, whether via rest, wcf etc., but the logic can just be thrown into the custom service
Related
iam trying to map just a long field coming from my url route to create a Query Object from my controller, can i use auto mapper
CreateMap(MemberList.None);
Source :-long id
Destination:-
public class GetPlanQuery : IRequest<PlanDto>
{
public long Id { get; }
public GetPlanQuery(long id)
{
Id = id;
}
internal sealed class GetPlanQueryHandler : IRequestHandler<GetPlanQuery, PlanDto>
{
//Logic will go here
}
}
Map i am using is as below
CreateMap<long, GetPlanQuery>(MemberList.None);
i am getting an exception while executing as
System.ArgumentException:
needs to have a constructor with 0 args or only optional args.'
As Lucian correctly suggested you can achieve this kind of custom mapping by implementing ITypeConverter:
public class LongToGetPlanQueryTypeConverter : ITypeConverter<long, GetPlanQuery>
{
public GetPlanQuery Convert(long source, GetPlanQuery destination, ResolutionContext context)
{
return new GetPlanQuery(source);
}
}
then specify it's usage in AutoMapper configuration:
configuration.CreateMap<long, GetPlanQuery>()
.ConvertUsing<LongToGetPlanQueryTypeConverter>();
EDIT
Alternatively, you can just use a Func:
configuration.CreateMap<long, GetPlanQuery>()
.ConvertUsing(id => new GetPlanQuery(id));
My current implementation for service and business layer is straight forward as below.
public class MyEntity { }
// Business layer
public interface IBusiness { IList<MyEntity> GetEntities(); }
public class MyBusinessOne : IBusiness
{
public IList<MyEntity> GetEntities()
{
return new List<MyEntity>();
}
}
//factory
public static class Factory
{
public static T Create<T>() where T : class
{
return new MyBusinessOne() as T; // returns instance based on T
}
}
//Service layer
public class MyService
{
public IList<MyEntity> GetEntities()
{
return Factory.Create<IBusiness>().GetEntities();
}
}
We needed some changes in current implementation. Reason being data grew over the time and service & client cannot handle the volume of data. we needed to implement pagination to the current service. We also expect some more features (like return fault when data is more that threshold, apply filters etc), so the design needs to be updated.
Following is my new proposal.
public interface IBusiness
{
IList<MyEntity> GetEntities();
}
public interface IBehavior
{
IEnumerable<T> Apply<T>(IEnumerable<T> data);
}
public abstract class MyBusiness
{
protected List<IBehavior> Behaviors = new List<IBehavior>();
public void AddBehavior(IBehavior behavior)
{
Behaviors.Add(behavior);
}
}
public class PaginationBehavior : IBehavior
{
public int PageSize = 10;
public int PageNumber = 2;
public IEnumerable<T> Apply<T>(IEnumerable<T> data)
{
//apply behavior here
return data
.Skip(PageNumber * PageSize)
.Take(PageSize);
}
}
public class MyEntity { }
public class MyBusinessOne : MyBusiness, IBusiness
{
public IList<MyEntity> GetEntities()
{
IEnumerable<MyEntity> result = new List<MyEntity>();
this.Behaviors.ForEach(rs =>
{
result = rs.Apply<MyEntity>(result);
});
return result.ToList();
}
}
public static class Factory
{
public static T Create<T>(List<IBehavior> behaviors) where T : class
{
// returns instance based on T
var instance = new MyBusinessOne();
behaviors.ForEach(rs => instance.AddBehavior(rs));
return instance as T;
}
}
public class MyService
{
public IList<MyEntity> GetEntities(int currentPage)
{
List<IBehavior> behaviors = new List<IBehavior>() {
new PaginationBehavior() { PageNumber = currentPage, }
};
return Factory.Create<IBusiness>(behaviors).GetEntities();
}
}
Experts please suggest me if my implementation is correct or I am over killing it. If it correct what design pattern it is - Decorator or Visitor.
Also my service returns JSON string. How can I use this behavior collections to serialize only selected properties rather than entire entity. List of properties comes from user as request. (Kind of column picker)
Looks like I don't have enough points to comment on your question. So, I am gonna make some assumption as I am not a C# expert.
Assumption 1: Looks like you are getting the data first and then applying the pagination using behavior object. If so, this is a wrong approach. Lets say there are 500 records and you are showing 50 records per fetch. Instead of simply fetching 50 records from DB, you are fetching 500 records for 10 times and on top of it you are adding a costly filter. DB is better equipped to do this job that C# or Java.
I would not consider pagination as a behavior with respect to the service. Its the behavior of the presentation layer. Your service should only worry about 'Data Granularity'. Looks like one of your customer wants all the data in one go and others might want a subset of that data.
Option 1: In DAO layer, have two methods: one for pagination and other for regular fetch. Based on the incoming params decide which method to call.
Option 2: Create two methods at service level. One for a small subset of data and the other for the whole set of data. Since you said JSON, this should be Restful service. Then based on the incoming URL, properly call the correct method. If you use Jersey, this should be easy.
In a service, new behaviors can be added by simply exposing new methods or adding new params to existing methods/functionalities (just make sure those changes are backward compatible). We really don't need Decorator or Visitor pattern. The only concern is no existing user should be affected.
I've been dealing with this issue for a while, and still can't seem to find a solution. I have several repositories which wrap an EF 4 ObjectContext. An example is below:
public class HGGameRepository : IGameRepository, IDisposable
{
private readonly HGEntities _context;
public HGGameRepository(HGEntities context)
{
this._context = context;
}
// methods
public void SaveGame(Game game)
{
if (game.GameID > 0)
{
_context.ObjectStateManager.ChangeObjectState(game, System.Data.EntityState.Modified);
}
else
{
_context.Games.AddObject(game);
}
_context.SaveChanges();
}
public void Dispose()
{
if (this._context != null)
{
this._context.Dispose();
}
}
}
And I have the following NinjectModule:
public class DIModule : NinjectModule
{
public override void Load()
{
this.Bind<HGEntities>().ToSelf();
this.Bind<IArticleRepository>().To<HGArticleRepository>();
this.Bind<IGameRepository>().To<HGGameRepository>();
this.Bind<INewsRepository>().To<HGNewsRepository>();
this.Bind<ErrorController>().ToSelf();
}
}
Since I'm using the MVC 2 extension, these bindings default to InRequestScope().
My problem is that the ObjectContext isn't being handled properly. I get what's described here: https://stackoverflow.com/a/5275849/399584 Specifically, I get an InvalidOperationException that states:
The relationship between the two objects cannot be defined because they are attached to different ObjectContext objects.
This happens every time I try to update an Entity.
If I set my repos to bind InSingletonScope() it works, but seems like a bad idea.
What am I doing wrong?
EDIT: For clarity, I have just one ObjectContext that I want to share with all my repos per request.
You have to specify InRequestScope() in your module. Based on this article the default to transient, which is why you are getting more than one context.
public class DIModule : NinjectModule
{
public override void Load()
{
this.Bind<HGEntities>().ToSelf().InRequestScope();
this.Bind<IArticleRepository>().To<HGArticleRepository>().InRequestScope();
this.Bind<IGameRepository>().To<HGGameRepository>().InRequestScope();
this.Bind<INewsRepository>().To<HGNewsRepository>().InRequestScope();
this.Bind<ErrorController>().ToSelf().InRequestScope();
}
}
Also did you add ninject to your project via nuget package manager or the old fashion way?
Consider the following existing classes which uses MEF to compose Consumer.
public interface IProducer
{
void Produce();
}
[Export(typeof(IProducer))]
public class Producer : IProducer
{
public Producer()
{
// perform some initialization
}
public void Produce()
{
// produce something
}
}
public class Consumer
{
[Import]
public IProducer Producer
{
get;
set;
}
[ImportingConstructor]
public Consumer(IProducer producer)
{
Producer = producer;
}
public void DoSomething()
{
// do something
Producer.Produce();
}
}
However, the creation of Producer has become complex enough that it can no longer be done within the constructor and the default behavior no longer suffices.
I'd like to introduce a factory and register it using a custom FactoryAttribute on the producer itself. This is what I have in mind:
[Export(typeof(IProducer))]
[Factory(typeof(ProducerFactory))]
public class Producer : IProducer
{
public Producer()
{
// perform some initialization
}
public void Produce()
{
// produce something
}
}
[Export]
public class ProducerFactory
{
public Producer Create()
{
// Perform complex initialization
return new Producer();
}
}
public class FactoryAttribute : Attribute
{
public Type ObjectType
{
get;
private set;
}
public FactoryAttribute(Type objectType)
{
ObjectType = objectType;
}
}
If I had to write the "new" code myself, it may very well look as follows. It would use the factory attribute, if it exists, to create a part, or default to the MEF to create it.
public object Create(Type partType, CompositionContainer container)
{
var attribute = (FactoryAttribute)partType.GetCustomAttributes(typeof (FactoryAttribute), true).FirstOrDefault();
if (attribute == null)
{
var result = container.GetExports(partType, null, null).First();
return result.Value;
}
else
{
var factoryExport = container.GetExports(attribute.ObjectType, null, null).First();
var factory = factoryExport.Value;
var method = factory.GetType().GetMethod("Create");
var result = method.Invoke(factory, new object[0]);
container.ComposeParts(result);
return result;
}
}
There are a number of articles how to implement a ExportProvider, including:
MEF + Object Factories using Export Provider
Dynamic Instantiation
However, the examples are not ideal when
The application has no dependencies or knowledge of Producer, only IProducer. It would not be able to register the factory when the CompositionContainer is created.
Producer is reused by several applications and a developer may mistakenly forget to register the factory when the CompositionContainer is created.
There are a large number of types that require custom factories and it may pose a maintenance nightmare to remember to register factories when the CompositionContainer is created.
I started to create a ExportProvider (assuming this would provide the means to implement construction using factory).
public class FactoryExportProvider : ExportProvider
{
protected override IEnumerable<Export> GetExportsCore(ImportDefinition definition,
AtomicComposition atomicComposition)
{
// What to do here?
}
}
However, I'm having trouble understanding how to tell MEF to use the factory objects defined in the FactoryAttribute, and use the default creation mechanism if no such attribute exists.
What is the correct manner to implement this? I'm using MEF 2 Preview 5 and .NET 4.
You can make use of a property export:
public class ProducerExporter
{
[Export]
public IProducer MyProducer
{
get
{
var producer = new Producer();
// complex initialization here
return producer;
}
}
}
Note that the term factory isn't really appropriate for your example, I would reserve that term for the case where the importer wants to create instances at will, possibly by providing one or more parameters. That could be done with a method export:
public class ProducerFactory
{
[Export(typeof(Func<Type1,Type2,IProducer>)]
public IProducer CreateProducer(Type1 arg1, Type2 arg2)
{
return new Producer(arg1, arg2);
}
}
On the import side, you would then import a Func<Type1,Type2,IProducer> that you can invoke at will to create new instances.
Given this class:
class Foo
{
readonly ILog log;
public Foo(ILog log)
{
this.log = log;
}
...
}
I'd like to configure Unity to inject ILog. That's easy:
container.RegisterInstance<ILog>(LogManager.GetLogger(typeof(XYZ)));
But I'd like to make Unity call LogManager.GetLogger with the type of the parent type being resolved.
This is close:
container.RegisterType<ILog>(new InjectionFactory((c, t, s) => LogManager.GetLogger(t)));
But t in this case is the type being resolved (ILog), not the type that the object is being resolved for (Foo).
I know I can do this:
container.RegisterType<Foo>(new InjectionFactory(c => new Foo(LogManager.GetLogger(typeof(Foo)));
But I don't want to have to add that crazy declaration every time I register an object.
I know this can be done in Autofac, and I know the Real Answer is not to use Unity in the first place, but can this be done? :)
Unity might not give you all the goodies some of the other containers offer but I have yet to find a feature you can't easily add.
var container = new UnityContainer();
container.AddNewExtension<TrackingExtension>();
container.RegisterType<ILog>(
new InjectionFactory((ctr, type, name) =>
{
var tracker = ctr.Resolve<ITracker>();
var parentType = tracker.CurrentBuildNode.Parent.BuildKey.Type;
return LogManager.GetLogger(parentType);
}));
var sut = container.Resolve<UsesLog>();
Assert.AreEqual(typeof(UsesLog), sut.Log.Type);
You can find the source code for the TrackingExtension here. Its located in the TecX.Unity project folder.
If you want a DI container to return you a logger based on the class’ type information, then put the type information into the public interface so the DI container can see it. It removes the need for any container specific override features and then it won’t matter if you are using Unity or AutoFac.
Someone that knows the log4net object model well might be able to give you a more efficient implementation, but try something like this:
using System;
using Microsoft.Practices.Unity;
using Microsoft.VisualStudio.TestTools.UnitTesting;
namespace UnityLoging
{
public interface ILog<T> : log4net.ILog
{ }
public class MyLogger<T> : log4net.Core.LogImpl, ILog<T>
{
public MyLogger() : base(log4net.LogManager.GetLogger(typeof(T).Name).Logger)
{ }
}
public class ClassToLog
{
private readonly log4net.ILog log;
public ClassToLog(ILog<ClassToLog> log)
{
this.log = log;
}
public void LogMe()
{
log.Debug("Got here");
}
}
[TestClass]
public class TestClass
{
[TestMethod]
public void GenericLogRegistrationTest()
{
log4net.Config.XmlConfigurator.Configure();
IUnityContainer container = new UnityContainer();
container.RegisterType(typeof(ILog<>), typeof(MyLogger<>));
ClassToLog c = container.Resolve<ClassToLog>();
c.LogMe();
log4net.LogManager.Shutdown();
}
}
}
This seems like a very clean approach: https://github.com/roblevine/UnityLoggingExtensions