WithCollectionProperty Icollection about epplus.dataextractor

[ipvalverde]

Hi @xavave, thanks for noticing that one.
Unfortunately, the SimpleCollectionColumnDataExtractor creates a new instance of the collection type inside of it. So in this case, it would try to create an insurance of ICollection<TCollectionItem>, that is why you see that error.

I'm not on my computer at the moment, I'll try to give a look into it tomorrow on how else this can be done. If you have any suggestions, feel free to share as well.

[xavave]

I've added a constructor with ObservableCollection, it should fit my requirements

[xavave]

Awesome ! Thank you !
I will take a look at your code to understand how you have made it

[ipvalverde]

You're welcome! Just released version 2.1.0 on Nuget with this feature

[xavave]

Hi Israel,
Can I use an observable Collection with this new implementation ?
I get an error :
public virtual ObservableCollection<Ingredient> FormulaIngredients { get => formulaIngredients; set => Set(ref formulaIngredients, value); }
error :
'Expression of type 'System.Collections.ObjectModel.Collection1[Formula.DAL.Model.Ingredient]' cannot be used for assignment to type 'System.Collections.ObjectModel.ObservableCollection1[Formula.DAL.Model.Ingredient]''

and
.WithCollectionProperty(p => p.FormulaIngredients,
1, "F", cfg => cfg
.WithProperty(ing => ing.TempImportId, "RM ID")
.WithProperty(ing => ing.MainTypeId, "RM type", FnConvertMainTypeName)
.WithProperty(ing => ing.Weight, "RM poids", fnParseDouble)
)

[ipvalverde]

Could you check if your formulaIngredients is null?

If it is null, since ObservableCollection inherits from Collection, the overload used in the WithCollectionProperty is the Collection one and then the code tries to create a new instance of Collection and assign it to your property...

[ipvalverde]

Nevermind, I was able to reproduce the issue, it is not related to the property being initialized or not. I should publish a fix by tomorrow.

[ipvalverde]

Thanks for noticing that error @xavave. Unfortunately, in order to provide a proper fix, I introduced a breaking change on version 2.2.0.

TL;DR
For your case, of an initialized collection property that is not a List<T>, HashSet<T> or Collection<T>, you can use the new method: WithInitializedCollectionProperty instead of WithCollectionProperty.

Full story
If you are using the method WithCollectionProperty for a collection property that is not a List<T>, HashSet<T> or a Collection<T>, an exception will be thrown at runtime. In your case, since your property is of type ObservableCollection<T>, the overload that accepts a Collection<T> is picked and this generates an error.
What should happen in this case, is that the overload with ICollection<T>, for initialized collection properties, should be picked instead. To prevent the necessity of specifying generic types when calling the method, now the WithCollectionProperty overloads that accept ICollection<T> are obsolete, new methods were created specifically for the ICollection<T>: WithInitializedCollectionProperty

[xavave]

thank you, it works with WithInitializedCollectionProperty