I'm trying to map a value object collection where these contain other value objects but am getting the below exception.
nHibernate Exception:
----> NHibernate.PropertyNotFoundException : Could not find a getter for property '_timeAtAddress' in class 'CustomerAddress'
Domain:
public class CustomerAddress
{
private TimePeriod _timeAtAddress;
protected CustomerAddress() { }
public CustomerAddress(TimePeriod timeAtAddress)
{
_timeAtAddress = timeAtAddress;
}
public TimePeriod TimeAtAddress { get { return _timeAtAddress; } }
}
public class TimePeriod
{
private readonly int _months;
private readonly int _years;
protected TimePeriod() { }
public TimePeriod(int months, int years)
{
_months = months;
_years = years;
}
public int Months { get { return _months; } }
public int Years { get { return _years; } }
}
nHibernate Mapping:
contact.HasMany<CustomerAddress>(Reveal.Member<Contact>("_customerAddresses"))
.Schema(...)
.Table(...)
.KeyColumn(...)
.AsBag()
.Not.LazyLoad()
.Component(address =>
{
.
.
.
address.Component(Reveal.Member<CustomerAddress, TimePeriod>("_timeAtAddress"), timeAtAddress =>
{
timeAtAddress.Map(Reveal.Member<TimePeriod>("_years")).Column("TIME_YEARS");
timeAtAddress.Map(Reveal.Member<TimePeriod>("_months")).Column("TIME_MONTHS");
});
});
Had a quick look at Access but can't seem to figure out where to set that up for components. Can you help?
Rather than configuring FluentNHibernate to set the private field, shouldn't you be telling it to use the constructor argument?
My gut feeling is that the mistake is here:
address.Component(Reveal.Member<CustomerAddress, TimePeriod>("_timeAtAddress")
Where you're telling it to use the field _timeAtAddress.
The only way I managed to move forward (using the private field) was to set a global Access.Field convention.
.Mappings(m => m.FluentMappings.AddFromAssemblyOf<Customer>()
.Conventions.Add(DefaultAccess.Field()))
Related
I have a class with a collection that needs validation. The generic on the collection takes an interface and different types can be added to the collection.
What is the cleanest path forward to creating a FluentValidation validator that supports polymorphism?
public interface IWizardStep {}
public class WizardOne : IWizardStep
{
public string Model { get; set; }
}
public class WizardTwo : IWizardStep
{
public string FirstName { get; set; }
}
public class Wizard
{
public Wizard()
{
var w1 = new WizardOne();
var w2 = new WizardTwo();
Steps = new List<IWizardStep>
{
w1,
w2
};
}
public IList<IWizardStep> Steps { get; set; }
}
public class WizardValidator : AbstractValidator<Wizard>
{
public WizardValidator()
{
RuleFor(x => x.Steps)
// Steps First where is WizardOne
// Model.NotEmpty()
// Steps First where is WizardTwo
// FirstName.NotEmpty()
}
FluentValidation doesn't support polymorphism for child collections like this out of the box, but you can add this behaviour by using a custom property validator, or by using OfType in your rule definitions.
I've written about both approaches before here:
Step 1: Create a validator for each implementor
Start by creating a validator for WizardOne and WizardTwo:
public class WizardOneValidator : AbstractValidator<WizardOne> {
public WizardOneValidator() {
RuleFor(x => x.Model).NotEmpty();
}
}
public class WizardTwoValidator : AbstractValidator<WizardTwo> {
public WizardTwoValidator() {
RuleFor(x => x.FirstName).NotEmpty();
}
}
Step 2: Create the parent validator
You have two options for defining the parent validator. The simplest approach is to use OfType, but this is less performant. The more complex option is to use a custom property validator.
Option 1: Using OfType
public WizardValidator : AbstractValidator<Wizard> {
public WizardValidator() {
RuleForEach(x => x.Steps.OfType<WizardOne>()).SetValidator(new WizardOneValidator());
RuleForEach(x => x.Steps.OfType<WizardTwo>()).SetValidator(new WizardTwoValidator());
}
}
This is the simplest approach, but calling OfType inside the call RuleFor will end up bypassing FluentValidation's expression cache, which is a potential performance hit. It also iterates the collection multiple. This may or may not be an issue for you - you'll need to decide if this has any real-world impact on your application.
Option 2: Using a custom PropertyValidator.
This uses a custom custom validator which can differentiate the underlying type at runtime:
public WizardValidator : AbstractValidator<Wizard> {
public WizardValidator() {
RuleForEach(x => x.Steps).SetValidator(new PolymorphicValidator<Wizard, IWizardStep>()
.Add<WizardOne>(new WizardOneValidator())
.Add<WizardTwo>(new WizardTwoValidator())
);
}
}
Syntactically, this isn't quite as nice, but doesn't bypass the expression cache and doesn't iterate the collection multiple times. This is the code for the PolymorphicValidator:
public class PolymorphicValidator<T, TInterface> : ChildValidatorAdaptor<T, TInterface> {
readonly Dictionary<Type, IValidator> _derivedValidators = new Dictionary<Type, IValidator>();
// Need the base constructor call, even though we're just passing null.
public PolymorphicValidator() : base((IValidator<TInterface>)null, typeof(IValidator<TInterface>)) {
}
public PolymorphicValidator<T, TInterface> Add<TDerived>(IValidator<TDerived> derivedValidator) where TDerived : TInterface {
_derivedValidators[typeof(TDerived)] = derivedValidator;
return this;
}
public override IValidator<TInterface> GetValidator(PropertyValidatorContext context) {
// bail out if the current item is null
if (context.PropertyValue == null) return null;
if (_derivedValidators.TryGetValue(context.PropertyValue.GetType(), out var derivedValidator)) {
return new ValidatorWrapper(derivedValidator);
}
return null;
}
private class ValidatorWrapper : AbstractValidator<TInterface> {
private IValidator _innerValidator;
public ValidatorWrapper(IValidator innerValidator) {
_innerValidator = innerValidator;
}
public override ValidationResult Validate(ValidationContext<TInterface> context) {
return _innerValidator.Validate(context);
}
public override Task<ValidationResult> ValidateAsync(ValidationContext<TInterface> context, CancellationToken cancellation = new CancellationToken()) {
return _innerValidator.ValidateAsync(context, cancellation);
}
public override IValidatorDescriptor CreateDescriptor() {
return _innerValidator.CreateDescriptor();
}
}
}
This will probably be implemented in the library as a first class feature at some point in the future - you can track its development here if you're interested.
I'm trying to map (by code) a protected collection to a bag but I'm struggling. e.g.
public class MyClass
{
....
protected virtual ICollection<Items> MyItems { get; set; }
....
}
public class MyClassMapping : ClassMapping<MyClass>
{
...
Bag(x => x.MyItems, map =>
{
....
}
...
}
It throws a mapping exception with the inner exception being "ArgumentNullException: Value cannot be null. Parameter name: localMember". It works fine if the "MyItems" collection is public.
I followed this article (https://groups.google.com/forum/#!topic/nhusers/wiH1DPGOhgU) which recommends using the method overload that takes a string. e.g.
public class MyClassMapping : ClassMapping<MyClass>
{
...
Bag("MyItems", map =>
{
....
}
...
}
But this gives a compilation error "The type arguments for method .... cannot be inferred from the usage. Try specifying the type arguments explicitly".
Is it possible to map to a protected collection (I'm using NH 3.3)? Can someone give me an example?
Thanks,
Chet
As we can see the overloaded method here: PropertyContainerCustomizer.cs
public void Bag<TElement>(string notVisiblePropertyOrFieldName
, Action<IBagPropertiesMapper<TEntity, TElement>> collectionMapping
, Action<ICollectionElementRelation<TElement>> mapping)
{ ... }
What we have to pass as the generic template is the TElement, the one used as ICollection<TElement>.
And because the defintion is:
// TElement is Items
protected virtual ICollection<Items> MyItems { get; set; }
SOLUTION: What we have to do is declare the mapping like this
// the TElement must be expressed explicitly as Items
Bag<Items>("MyItems", map =>
{
....
}
With the following:
public class AClass
{
public ADependent Dependent { get; set; }
}
public class ADependent
{
public ADependent(AClass ownerValue) {}
}
with the following registrations...
builder.RegisterType<AClass>().PropertiesAutowired().InstancePerDependency();
builder.RegisterType<ADependent>().PropertiesAutowired().InstancePerDependency();
When I resolve an AClass, how do I make sure that 'ownerValue' is the instance of AClass being resolved, and not another instance? Thx
FOLLOW ON
The example above doesn't really catch the problem properly, which is how to wire up ADependent when registering when scanning... for example
public class AClass : IAClass
{
public IADependent Dependent { get; set; }
}
public class ADependent : IADependent
{
public ADependent(IAClass ownerValue) {}
}
// registrations...
builder.RegisterAssemblyTypes(assemblies)
.AssignableTo<IAClass>()
.As<IAClass>()
.InstancePerDependency()
.PropertiesAutowired();
builder.RegisterAssemblyTypes(assemblies)
.AssignableTo<IADependent>()
.As<IADependent>()
.InstancePerDependency()
.PropertiesAutowired();
The function I am looking for really is another relationship type like
public class ADependent : IADependent
{
public ADependent(OwnedBy<IAClass> ownerValue) {}
}
The OwnedBy indicates that ownerValue is the instance that caused ADependent to created. Does something like this make sense? It would certainly make wiring up UI components a breeze.
To extend Steven's approach, you can even Resolve() the second class, passing the first instance as a parameter:
builder.RegisterType<ADependent>();
builder.Register<AClass>(c =>
{
var a = new AClass();
a.Dependent = c.Resolve<ADependent>(TypedParameter.From(a));
return a;
});
You can register a lambda to do the trick:
builder.Register<AClass>(_ =>
{
var a = new AClass();
a.Dependent = new ADependent(a);
return a;
});
All of my entities and value objects implement marker interfaces IEntity and IValueObject. I have set them up to be treated as components like so:
public override bool IsComponent(Type type)
{
return typeof(IValueObject).IsAssignableFrom(type);
}
public override bool ShouldMap(Type type)
{
return typeof(IEntity).IsAssignableFrom(type) || typeof(IValueObject).IsAssignableFrom(type);
}
Unfortunately, this does not seem to allow entities that have collections of value objects to be automapped as component collections. For example:
public class MyEntity : IEntity
{
public IList<MyValueObject> Objects { get; set; }
}
public class MyValueObject : IValueObject
{
public string Name { get; set; }
public string Value { get; set; }
}
Is there any way to define a convention such that, any time an IEntity has an IList of a type that implements IValueObject, it gets mapped as if I had specified:
HasMany(x => x.Objects)
.Component(x => {
x.Map(m => m.Name);
x.Map(m => m.Value);
});
What I don't want to do is have to manually do these overrides for every class and write out each property for the value object again and again.
Create a new class that inherits from HasManyStep (FluentNHibernate.Automapping.Steps).
Override the ShouldMap() method with something like :
return base.ShouldMap(member) && IsCollectionOfComponents(member)
Add your logic to :
public void Map(ClassMappingBase classMap, Member member)
{ ... }
Replace the default step with your new one :
public class MyMappingConfiguration : DefaultAutomappingConfiguration
{
public override IEnumerable<IAutomappingStep> GetMappingSteps(AutoMapper mapper, IConventionFinder conventionFinder)
{
var steps = base.GetMappingSteps(mapper, conventionFinder);
var finalSteps = steps.Where(c => c.GetType() != typeof(FluentNHibernate.Automapping.Steps.HasManyToManyStep)).ToList();
var idx = finalSteps.IndexOf(steps.Where(c => c.GetType() == typeof(PropertyStep)).First());
finalSteps.Insert(idx + 1, new MyCustomHasManyStep(this));
return finalSteps;
}
}
Note : You could also get the original source code of HasManyStep.cs and copy it to your project to introduce your custom logic.
I found this article on Context Variables in an earlier version of Ninject. My question is two-fold. First, how can I get this behavior with Ninject 2? Secondly, do context variables carry through down the request chain? For example, let's say I wanted to replace these calls:
var a = new A(new B(new C())));
var specialA = new A(new B(new SpecialC()));
... with this:
var a = kernel.Get<A>();
var specialA = kernel.Get<A>(With.Parameters.ContextVariable("special", "true"));
Is it possible to set up a binding like this, where the context remembers that it is in a "special" context when it comes time to construct a C?
Here's some stuff that I use against V2, with ~0 effort to clean it up for you - let me know if you can't disentagle it.
As you surmised, there doesn't seem to be a really explicit API that surfaces the "context parameter, even for nested resolutions" stuff in v2 as-is (it's presence is buried as the 3rd parameter on an overload of the Parameter ctor).
public static class ContextParameter
{
public static Parameter Create<T>( T value )
{
return new Parameter( value.GetType().FullName, value, true );
}
}
public static class ContextParameterFacts
{
public class ProductId
{
public ProductId( string productId2 )
{
Value = productId2;
}
public string Value { get; set; }
}
public class Repository
{
public Repository( ProductId productId )
{
ProductId = productId;
}
public ProductId ProductId { get; set; }
}
public class Outer
{
public Outer( Repository repository )
{
Repository = repository;
}
public Repository Repository { get; set; }
}
public class Module : NinjectModule
{
public override void Load()
{
Bind<ProductId>().ToContextParameter();
}
}
//[ Fact ]
public static void TwoDeepShouldResolve()
{
var k = new StandardKernel( new Module() );
var o = k.Get<Outer>( ContextParameter.Create( new ProductId( "a" ) ) );
Debug.Assert( "a" == o.Repository.ProductId.Value );
}
}
And here's some code [that'll confuse the matter] which demonstrates how I apply it in my context:-
public class ServicesNinjectModule : NinjectModule
{
public override void Load()
{
Bind<ProductId>().ToContextParameter();
Bind<Func<ProductId, ResourceAllocator>>().ToConstant( ( productId ) => Kernel.Get<ResourceAllocator>(
ContextParameter.Create( productId ) ) );
}
}
public static class NinjectContextParameterExtensions
{
public static IBindingWhenInNamedWithOrOnSyntax<T> ToContextParameter<T>( this IBindingToSyntax<T> bindingToSyntax )
{
return bindingToSyntax.ToMethod( context => (T)context.Parameters.Single( parameter => parameter.Name == typeof( T ).FullName ).GetValue( context ) );
}
}
As usual, you should go look a the source and the tests - they'll provide you with a far more detailed and relevant answer than I can.