/// <summary>
/// Retrieves the changes between <paramref name="oldVersion"/> and <paramref name="newVersion"/>.
/// <paramref name="hasChanged"/> will be true if the return value has any entries, false otherwise.
/// </summary>
/// <param name="newVersion">The properties associated with the new version of the object.</param>
/// <param name="oldVersion">The properties associated with the old version of the object.</param>
/// <param name="hasChanged">Whether there are any changes.</param>
/// <param name="includePropertiesThatHaveNotChanged">If false, the returned collection will have unchanged items removed.</param>
/// <returns>The changes.</returns>
public static IEnumerable <PropertyValueChange> GetChanges
(
this PropertyValues newVersion,
PropertyValues oldVersion,
out bool hasChanged,
bool includePropertiesThatHaveNotChanged = false
)
{
// Sanity.
newVersion = newVersion ?? new PropertyValues();
oldVersion = oldVersion ?? new PropertyValues();
// Will contain all properties, not just changes.
var allProps = new List <PropertyValueChange>();
// Loop over new properties and find new or changed values.
foreach (PropertyValue newPropVal in newVersion)
{
allProps.Add
(
new PropertyValueChange
(
oldVersion?.GetProperty(newPropVal.PropertyDef),
newPropVal
)
);
}
// Loop over old properties to find removed values.
if (oldVersion != null)
{
foreach (PropertyValue oldPropVal in oldVersion)
{
if (!newVersion.Exists(oldPropVal.PropertyDef))
{
allProps.Add(new PropertyValueChange(oldPropVal, null));
}
}
}
// Ignore anything that has not changed.
var changedProperties = allProps.Where(p => p.ChangeType != PropertyValueChangeType.None);
// Set the out variable.
hasChanged = changedProperties.Any();
// Return the changes.
return(includePropertiesThatHaveNotChanged
? allProps
: changedProperties);
}