internal async Task <ModelBindingResult> TryBindStrongModel <TModel>(
ModelBindingContext parentBindingContext,
string propertyName)
{
var propertyModelMetadata =
parentBindingContext.OperationBindingContext.MetadataProvider.GetMetadataForType(typeof(TModel));
var propertyModelName =
ModelNames.CreatePropertyModelName(parentBindingContext.ModelName, propertyName);
var propertyBindingContext = ModelBindingContext.CreateChildBindingContext(
parentBindingContext,
propertyModelMetadata,
propertyName,
propertyModelName,
model: null);
var result = await propertyBindingContext.OperationBindingContext.ModelBinder.BindModelAsync(
propertyBindingContext);
if (result.IsModelSet)
{
return(result);
}
else
{
return(ModelBindingResult.Failed(propertyModelName));
}
}
// Returned dictionary contains entries corresponding to properties against which binding was attempted. If
// binding failed, the entry's value will have IsModelSet == false. Binding is attempted for all elements of
// propertyMetadatas.
private async Task <IDictionary <ModelMetadata, ModelBindingResult> > BindPropertiesAsync(
ModelBindingContext bindingContext,
IEnumerable <ModelMetadata> propertyMetadatas)
{
var results = new Dictionary <ModelMetadata, ModelBindingResult>();
foreach (var propertyMetadata in propertyMetadatas)
{
// ModelBindingContext.Model property values may be non-null when invoked via TryUpdateModel(). Pass
// complex (including collection) values down so that binding system does not unnecessarily recreate
// instances or overwrite inner properties that are not bound. No need for this with simple values
// because they will be overwritten if binding succeeds. Arrays are never reused because they cannot
// be resized.
object model = null;
if (propertyMetadata.PropertyGetter != null &&
propertyMetadata.IsComplexType &&
!propertyMetadata.ModelType.IsArray)
{
model = propertyMetadata.PropertyGetter(bindingContext.Model);
}
var fieldName = propertyMetadata.BinderModelName ?? propertyMetadata.PropertyName;
var modelName = ModelNames.CreatePropertyModelName(bindingContext.ModelName, fieldName);
var propertyContext = ModelBindingContext.CreateChildBindingContext(
bindingContext,
propertyMetadata,
fieldName: fieldName,
modelName: modelName,
model: model);
var result = await bindingContext.OperationBindingContext.ModelBinder.BindModelAsync(propertyContext);
if (result == ModelBindingResult.NoResult)
{
// Could not bind. Let ProcessResult() know explicitly.
result = ModelBindingResult.Failed(propertyContext.ModelName);
}
results[propertyMetadata] = result;
}
return(results);
}
// Used when the ValueProvider contains the collection to be bound as a single element, e.g. the raw value
// is [ "1", "2" ] and needs to be converted to an int[].
// Internal for testing.
internal async Task <CollectionResult> BindSimpleCollection(
ModelBindingContext bindingContext,
ValueProviderResult values)
{
var boundCollection = new List <TElement>();
var metadataProvider = bindingContext.OperationBindingContext.MetadataProvider;
var elementMetadata = metadataProvider.GetMetadataForType(typeof(TElement));
var innerBindingContext = ModelBindingContext.CreateChildBindingContext(
bindingContext,
elementMetadata,
fieldName: bindingContext.FieldName,
modelName: bindingContext.ModelName,
model: null);
foreach (var value in values)
{
innerBindingContext.ValueProvider = new CompositeValueProvider
{
// our temporary provider goes at the front of the list
new ElementalValueProvider(bindingContext.ModelName, value, values.Culture),
bindingContext.ValueProvider
};
object boundValue = null;
var result =
await bindingContext.OperationBindingContext.ModelBinder.BindModelAsync(innerBindingContext);
if (result != null && result.IsModelSet)
{
boundValue = result.Model;
boundCollection.Add(ModelBindingHelper.CastOrDefault <TElement>(boundValue));
}
}
return(new CollectionResult
{
Model = boundCollection
});
}
private bool CanValueBindAnyModelProperties(MutableObjectBinderContext context)
{
// If there are no properties on the model, there is nothing to bind. We are here means this is not a top
// level object. So we return false.
if (context.PropertyMetadata == null || context.PropertyMetadata.Count == 0)
{
return(false);
}
// We want to check to see if any of the properties of the model can be bound using the value providers,
// because that's all that MutableObjectModelBinder can handle.
//
// However, because a property might specify a custom binding source ([FromForm]), it's not correct
// for us to just try bindingContext.ValueProvider.ContainsPrefixAsync(bindingContext.ModelName),
// because that may include ALL value providers - that would lead us to mistakenly create the model
// when the data is coming from a source we should use (ex: value found in query string, but the
// model has [FromForm]).
//
// To do this we need to enumerate the properties, and see which of them provide a binding source
// through metadata, then we decide what to do.
//
// If a property has a binding source, and it's a greedy source, then it's not
// allowed to come from a value provider, so we skip it.
//
// If a property has a binding source, and it's a non-greedy source, then we'll filter the
// the value providers to just that source, and see if we can find a matching prefix
// (see CanBindValue).
//
// If a property does not have a binding source, then it's fair game for any value provider.
//
// If any property meets the above conditions and has a value from valueproviders, then we'll
// create the model and try to bind it. OR if ALL properties of the model have a greedy source,
// then we go ahead and create it.
//
var isAnyPropertyEnabledForValueProviderBasedBinding = false;
foreach (var propertyMetadata in context.PropertyMetadata)
{
// This check will skip properties which are marked explicitly using a non value binder.
var bindingSource = propertyMetadata.BindingSource;
if (bindingSource == null || !bindingSource.IsGreedy)
{
isAnyPropertyEnabledForValueProviderBasedBinding = true;
var fieldName = propertyMetadata.BinderModelName ?? propertyMetadata.PropertyName;
var modelName = ModelNames.CreatePropertyModelName(
context.ModelBindingContext.ModelName,
fieldName);
var propertyModelBindingContext = ModelBindingContext.CreateChildBindingContext(
context.ModelBindingContext,
propertyMetadata,
fieldName: fieldName,
modelName: modelName,
model: null);
// If any property can return a true value.
if (CanBindValue(propertyModelBindingContext))
{
return(true);
}
}
}
if (!isAnyPropertyEnabledForValueProviderBasedBinding)
{
// Either there are no properties or all the properties are marked as
// a non value provider based marker.
// This would be the case when the model has all its properties annotated with
// a IBinderMetadata. We want to be able to create such a model.
return(true);
}
return(false);
}
/// <inheritdoc />
public override async Task <ModelBindingResult> BindModelAsync([NotNull] ModelBindingContext bindingContext)
{
var result = await base.BindModelAsync(bindingContext);
if (!result.IsModelSet)
{
// No match for the prefix at all.
return(result);
}
Debug.Assert(result.Model != null);
var model = (IDictionary <TKey, TValue>)result.Model;
if (model.Count != 0)
{
// ICollection<KeyValuePair<TKey, TValue>> approach was successful.
return(result);
}
var enumerableValueProvider = bindingContext.ValueProvider as IEnumerableValueProvider;
if (enumerableValueProvider == null)
{
// No IEnumerableValueProvider available for the fallback approach. For example the user may have
// replaced the ValueProvider with something other than a CompositeValueProvider.
return(result);
}
// Attempt to bind dictionary from a set of prefix[key]=value entries. Get the short and long keys first.
var keys = enumerableValueProvider.GetKeysFromPrefix(bindingContext.ModelName);
if (!keys.Any())
{
// No entries with the expected keys.
return(result);
}
// Update the existing successful but empty ModelBindingResult.
var metadataProvider = bindingContext.OperationBindingContext.MetadataProvider;
var valueMetadata = metadataProvider.GetMetadataForType(typeof(TValue));
var valueBindingContext = ModelBindingContext.CreateChildBindingContext(
bindingContext,
valueMetadata,
fieldName: bindingContext.FieldName,
modelName: bindingContext.ModelName,
model: null);
var modelBinder = bindingContext.OperationBindingContext.ModelBinder;
var keyMappings = new Dictionary <string, TKey>(StringComparer.Ordinal);
foreach (var kvp in keys)
{
// Use InvariantCulture to convert the key since ExpressionHelper.GetExpressionText() would use
// that culture when rendering a form.
var convertedKey = ModelBindingHelper.ConvertTo <TKey>(kvp.Key, culture: null);
valueBindingContext.ModelName = kvp.Value;
var valueResult = await modelBinder.BindModelAsync(valueBindingContext);
// Always add an entry to the dictionary but validate only if binding was successful.
model[convertedKey] = ModelBindingHelper.CastOrDefault <TValue>(valueResult.Model);
keyMappings.Add(kvp.Key, convertedKey);
}
bindingContext.ValidationState.Add(model, new ValidationStateEntry()
{
Strategy = new ShortFormDictionaryValidationStrategy <TKey, TValue>(keyMappings, valueMetadata),
});
return(result);
}
// Internal for testing.
internal async Task <CollectionResult> BindComplexCollectionFromIndexes(
ModelBindingContext bindingContext,
IEnumerable <string> indexNames)
{
bool indexNamesIsFinite;
if (indexNames != null)
{
indexNamesIsFinite = true;
}
else
{
indexNamesIsFinite = false;
indexNames = Enumerable.Range(0, int.MaxValue)
.Select(i => i.ToString(CultureInfo.InvariantCulture));
}
var metadataProvider = bindingContext.OperationBindingContext.MetadataProvider;
var elementMetadata = metadataProvider.GetMetadataForType(typeof(TElement));
var boundCollection = new List <TElement>();
foreach (var indexName in indexNames)
{
var fullChildName = ModelNames.CreateIndexModelName(bindingContext.ModelName, indexName);
var childBindingContext = ModelBindingContext.CreateChildBindingContext(
bindingContext,
elementMetadata,
fieldName: indexName,
modelName: fullChildName,
model: null);
var didBind = false;
object boundValue = null;
var result =
await bindingContext.OperationBindingContext.ModelBinder.BindModelAsync(childBindingContext);
if (result != null && result.IsModelSet)
{
didBind = true;
boundValue = result.Model;
}
// infinite size collection stops on first bind failure
if (!didBind && !indexNamesIsFinite)
{
break;
}
boundCollection.Add(ModelBindingHelper.CastOrDefault <TElement>(boundValue));
}
return(new CollectionResult
{
Model = boundCollection,
// If we're working with a fixed set of indexes then this is the format like:
//
// ?parameter.index=zero,one,two¶meter[zero]=0&¶meter[one]=1¶meter[two]=2...
//
// We need to provide this data to the validation system so it can 'replay' the keys.
// But we can't just set ValidationState here, because it needs the 'real' model.
ValidationStrategy = indexNamesIsFinite ?
new ExplicitIndexCollectionValidationStrategy(indexNames) :
null,
});
}