This change no longer suppresses validation for IFormFile and
IFormFileCollection model values. This will allow the use of [Required] on an
IFormFile model, or a custom attribute for validating IFormFileCollection.
These types already have ValidateChildren = false, so we don't recurse
into them.
This change separates model binding into IModelBinderProvider (decides
which binder to use) and IModelBinder (does binding). The
IModelBinderFactory is a new services with coordinates the creation of
model binders.
- #3482
- see new tests; many failed without fixes in the product code
- add support for binding `IFormFileCollection` properties
- make `FormFileModelBinder` / `HeaderModelBinder` collection handling consistent w/ `GenericModelBinder`++
- see also dupe bug #4129 which describes some of the prior inconsistencies
- add checks around creating collections and leaving non-top-level collections `null` (not empty)
- move smarts down to `ModelBindingHelper.GetCompatibleCollection<T>()` (was `ConvertValuesToCollectionType<T>()`)
- add `ModelBindingHelper.CanGetCompatibleCollection()`
- add fallback for cases like `public IEnumerable<T> Property { get; set; } = new T[0];`
- #4193
- allow `Exception`s while activating collections to propagate
- part of #4181
- `CollectionModelBinder` no longer creates an instance to check if it can create an instance
- not a complete fix since it still creates unnecessary intermediate lists
nits:
- correct a few existing test names since nothing is not the same as `ModelBindingResult.Failed()`
- remove a couple of unnecessary `return` statements
- correct stale "optimized" comments
- explicit `(string)`
Doug Bunting
Ryan Nowak
N. Taylor Mullen