|
namespace System.Web.ModelBinding {
using System;
using System.Collections.Generic;
using System.ComponentModel;
using System.Globalization;
using System.Linq;
// This class provides a good implementation of ModelMetadataProvider for people who will be
// using traditional classes with properties. It uses the buddy class support from
// DataAnnotations, and consolidates the three operations down to a single override
// for reading the attribute values and creating the metadata class.
public abstract class AssociatedMetadataProvider : ModelMetadataProvider {
private static void ApplyMetadataAwareAttributes(IEnumerable<Attribute> attributes, ModelMetadata result) {
foreach (IMetadataAware awareAttribute in attributes.OfType<IMetadataAware>()) {
awareAttribute.OnMetadataCreated(result);
}
}
protected abstract ModelMetadata CreateMetadata(IEnumerable<Attribute> attributes, Type containerType, Func<object> modelAccessor, Type modelType, string propertyName);
protected virtual IEnumerable<Attribute> FilterAttributes(Type containerType, PropertyDescriptor propertyDescriptor, IEnumerable<Attribute> attributes) {
return attributes;
}
public override IEnumerable<ModelMetadata> GetMetadataForProperties(object container, Type containerType) {
if (containerType == null) {
throw new ArgumentNullException("containerType");
}
return GetMetadataForPropertiesImpl(container, containerType);
}
private IEnumerable<ModelMetadata> GetMetadataForPropertiesImpl(object container, Type containerType) {
foreach (PropertyDescriptor property in GetTypeDescriptor(containerType).GetProperties()) {
Func<object> modelAccessor = container == null ? null : GetPropertyValueAccessor(container, property);
yield return GetMetadataForProperty(modelAccessor, containerType, property);
}
}
public override ModelMetadata GetMetadataForProperty(Func<object> modelAccessor, Type containerType, string propertyName) {
if (containerType == null) {
throw new ArgumentNullException("containerType");
}
if (String.IsNullOrEmpty(propertyName)) {
throw new ArgumentException(SR.GetString(SR.Common_NullOrEmpty), "propertyName");
}
ICustomTypeDescriptor typeDescriptor = GetTypeDescriptor(containerType);
PropertyDescriptor property = typeDescriptor.GetProperties().Find(propertyName, true);
if (property == null) {
throw new ArgumentException(
String.Format(
CultureInfo.CurrentCulture,
SR.GetString(SR.Common_PropertyNotFound),
containerType.FullName, propertyName));
}
return GetMetadataForProperty(modelAccessor, containerType, property);
}
protected virtual ModelMetadata GetMetadataForProperty(Func<object> modelAccessor, Type containerType, PropertyDescriptor propertyDescriptor) {
IEnumerable<Attribute> attributes = FilterAttributes(containerType, propertyDescriptor, propertyDescriptor.Attributes.Cast<Attribute>());
ModelMetadata result = CreateMetadata(attributes, containerType, modelAccessor, propertyDescriptor.PropertyType, propertyDescriptor.Name);
ApplyMetadataAwareAttributes(attributes, result);
return result;
}
public override ModelMetadata GetMetadataForType(Func<object> modelAccessor, Type modelType) {
if (modelType == null) {
throw new ArgumentNullException("modelType");
}
IEnumerable<Attribute> attributes = GetTypeDescriptor(modelType).GetAttributes().Cast<Attribute>();
ModelMetadata result = CreateMetadata(attributes, null /* containerType */, modelAccessor, modelType, null /* propertyName */);
ApplyMetadataAwareAttributes(attributes, result);
return result;
}
private static Func<object> GetPropertyValueAccessor(object container, PropertyDescriptor property) {
return () => property.GetValue(container);
}
protected virtual ICustomTypeDescriptor GetTypeDescriptor(Type type) {
return TypeDescriptorHelper.Get(type);
}
}
}
|