- #2941
- honor `ModelBindingResult.IsModelSet` and use `ModelBindingResult.ValidationNode`
- enable correct validation of collections or after model binding falls back to the empty prefix
- code previously matched `Controller.TryValidateModel()`; less context available in that case
- #2836
Part 1: Use existing property values when recursing in `MutableObjectModelBinder`
- remove `ComplexModelDTO` because that indirection made fixing this issue more difficult and doesn't add value
- started with an old closed PR (#2241) which did some of this work
- correct `MutableObjectModelBinderTest` tests that exercised behaviour that can't occur
- the old `dto.Results` dictionary was never incomplete; nor could it contain `null` values
Part 2: Change `MutableObjectModelBinder` to pass complex property values into binding system
- model binding no longer trounces nodes in the model tree that aren't bound
- create model instances less often in `TryUpdateModel` scenarios
- refactor `EnsureModel()` to `GetModel()` and use appropriately
- reorder logic in `SetProperty()` and `AddToProperty()` to avoid copying to / from the same collection
- also cleans up some code duplication
nits:
- clean up `MutableObjectModelBinderTest`
- fix odd line wrappings and indentation
- use `nameof()` more
- use `string.Empty` more
- simplify a couple of `Returns()` expressions
- make assertions in `TryUpdateModelIntegrationTest` more readable
- no need to work through `ModelStateDictionary.Keys`
- also use `Length` instead of `Count()`; test code but we don't need Linq at all in that test class
- #2793
- add `ICollectionModelBinder`, allowing `GenericModelBinder` to call `CreateEmptyCollection()`
- adjust `CollectionModelBinder` and `DictionaryModelBinder` to activate model if default types are incompatible
- do not create default (empty) top-level collection in fallback case if Model already non-`null`
- change type checks in `GenericModelBinder` to align with `CollectionModelBinder` capabilities
- add special case for `IEnumerable<T>`
- correct `ModelMetadata` of a few tests that previously did not need that information
The assumption is ModelState should have entries if
1. An error is explicitly added by a model binder.
2. There is validation error reported while validating the model.
3. There is value bound by the model binder.
With this change there should be no extra entry other than for the cases mentioned above.
Also enabling the integration test cases.