namespace Umbraco.Core.Models.PublishedContent
{
///
/// Provides a fallback strategy for getting values.
///
public interface IPublishedValueFallback
{
///
/// Tries to get a fallback value for a property.
///
/// The property.
/// The requested culture.
/// The requested segment.
/// A fallback strategy.
/// An optional default value.
/// The fallback value.
/// A value indicating whether a fallback value could be provided.
///
/// This method is called whenever property.Value(culture, segment, defaultValue) is called, and
/// property.HasValue(culture, segment) is false.
/// It can only fallback at property level (no recurse).
/// At property level, property.GetValue() does *not* implement fallback, and one has to
/// get property.Value() or property.Value{T}() to trigger fallback.
/// Note that and may not be contextualized,
/// so the variant context should be used to contextualize them (see our default implementation in
/// the web project.
///
bool TryGetValue(IPublishedProperty property, string culture, string segment, Fallback fallback, object defaultValue, out object value);
///
/// Tries to get a fallback value for a property.
///
/// The type of the value.
/// The property.
/// The requested culture.
/// The requested segment.
/// A fallback strategy.
/// An optional default value.
/// The fallback value.
/// A value indicating whether a fallback value could be provided.
///
/// This method is called whenever property.Value{T}(culture, segment, defaultValue) is called, and
/// property.HasValue(culture, segment) is false.
/// It can only fallback at property level (no recurse).
/// At property level, property.GetValue() does *not* implement fallback, and one has to
/// get property.Value() or property.Value{T}() to trigger fallback.
///
bool TryGetValue(IPublishedProperty property, string culture, string segment, Fallback fallback, T defaultValue, out T value);
///
/// Tries to get a fallback value for a published element property.
///
/// The published element.
/// The property alias.
/// The requested culture.
/// The requested segment.
/// A fallback strategy.
/// An optional default value.
/// The fallback value.
/// A value indicating whether a fallback value could be provided.
///
/// This method is called whenever getting the property value for the specified alias, culture and
/// segment, either returned no property at all, or a property with HasValue(culture, segment) being false.
/// It can only fallback at element level (no recurse).
///
bool TryGetValue(IPublishedElement content, string alias, string culture, string segment, Fallback fallback, object defaultValue, out object value);
///
/// Tries to get a fallback value for a published element property.
///
/// The type of the value.
/// The published element.
/// The property alias.
/// The requested culture.
/// The requested segment.
/// A fallback strategy.
/// An optional default value.
/// The fallback value.
/// A value indicating whether a fallback value could be provided.
///
/// This method is called whenever getting the property value for the specified alias, culture and
/// segment, either returned no property at all, or a property with HasValue(culture, segment) being false.
/// It can only fallback at element level (no recurse).
///
bool TryGetValue(IPublishedElement content, string alias, string culture, string segment, Fallback fallback, T defaultValue, out T value);
///
/// Tries to get a fallback value for a published content property.
///
/// The published element.
/// The property alias.
/// The requested culture.
/// The requested segment.
/// A fallback strategy.
/// An optional default value.
/// The fallback value.
/// The property that does not have a value.
/// A value indicating whether a fallback value could be provided.
///
/// This method is called whenever getting the property value for the specified alias, culture and
/// segment, either returned no property at all, or a property with HasValue(culture, segment) being false.
/// In an , because walking up the tree is possible, the content itself may not even
/// have a property with the specified alias, but such a property may exist up in the tree. The
/// parameter is used to return a property with no value. That can then be used to invoke a converter and get the
/// converter's interpretation of "no value".
///
bool TryGetValue(IPublishedContent content, string alias, string culture, string segment, Fallback fallback, object defaultValue, out object value, out IPublishedProperty noValueProperty);
///
/// Tries to get a fallback value for a published content property.
///
/// The type of the value.
/// The published element.
/// The property alias.
/// The requested culture.
/// The requested segment.
/// A fallback strategy.
/// An optional default value.
/// The fallback value.
/// The property that does not have a value.
/// A value indicating whether a fallback value could be provided.
///
/// This method is called whenever getting the property value for the specified alias, culture and
/// segment, either returned no property at all, or a property with HasValue(culture, segment) being false.
/// In an , because walking up the tree is possible, the content itself may not even
/// have a property with the specified alias, but such a property may exist up in the tree. The
/// parameter is used to return a property with no value. That can then be used to invoke a converter and get the
/// converter's interpretation of "no value".
///
bool TryGetValue(IPublishedContent content, string alias, string culture, string segment, Fallback fallback, T defaultValue, out T value, out IPublishedProperty noValueProperty);
}
}