/// <summary>
/// Gets the value of a content's property identified by its alias, converted to a specified type.
/// </summary>
/// <typeparam name="T">The target property type.</typeparam>
/// <param name="content">The content.</param>
/// <param name="publishedValueFallback">The published value fallback implementation.</param>
/// <param name="alias">The property alias.</param>
/// <param name="culture">The variation language.</param>
/// <param name="segment">The variation segment.</param>
/// <param name="fallback">Optional fallback strategy.</param>
/// <param name="defaultValue">The default value.</param>
/// <returns>The value of the content's property identified by the alias, converted to the specified type.</returns>
/// <remarks>
/// <para>
/// The value comes from <c>IPublishedProperty</c> field <c>Value</c> ie it is suitable for use when rendering
/// content.
/// </para>
/// <para>
/// If no property with the specified alias exists, or if the property has no value, or if it could not be
/// converted, returns <c>default(T)</c>.
/// </para>
/// <para>
/// If eg a numeric property wants to default to 0 when value source is empty, this has to be done in the
/// converter.
/// </para>
/// <para>The alias is case-insensitive.</para>
/// </remarks>
public static T?Value <T>(
this IPublishedElement content,
IPublishedValueFallback publishedValueFallback,
string alias,
string?culture = null,
string?segment = null,
Fallback fallback = default,
T?defaultValue = default)
{
IPublishedProperty?property = content.GetProperty(alias);
// if we have a property, and it has a value, return that value
if (property != null && property.HasValue(culture, segment))
{
return(property.Value <T>(publishedValueFallback, culture, segment));
}
// else let fallback try to get a value
if (publishedValueFallback.TryGetValue(content, alias, culture, segment, fallback, defaultValue, out T? value))
{
return(value);
}
// else... if we have a property, at least let the converter return its own
// vision of 'no value' (could be an empty enumerable) - otherwise, default
return(property == null ? default : property.Value <T>(publishedValueFallback, culture, segment));
}
public static object?Value(this IPublishedProperty property, IPublishedValueFallback publishedValueFallback, string?culture = null, string?segment = null, Fallback fallback = default, object?defaultValue = default)
{
if (property.HasValue(culture, segment))
{
return(property.GetValue(culture, segment));
}
return(publishedValueFallback.TryGetValue(property, culture, segment, fallback, defaultValue, out var value)
? value
: property.GetValue(culture, segment)); // give converter a chance to return it's own vision of "no value"
}