Add IsCollection function to all base objects

activity.go

@@ -821,6 +821,11 @@ func (i IntransitiveActivity) IsObject() bool {
 	return true
 }
 
+// IsCollection returns false for IntransitiveActivity objects
+func (i IntransitiveActivity) IsCollection() bool {
+	return false
+}
+
 // GetType returns the ActivityVocabulary type of the current Activity
 func (a Activity) GetType() ActivityVocabularyType {
 	return a.Type
@@ -846,6 +851,11 @@ func (a Activity) IsObject() bool {
 	return true
 }
 
+// IsCollection returns false for Activity objects
+func (a Activity) IsCollection() bool {
+	return false
+}
+
 // GetID returns the ObjectID corresponding to the Like object
 func (l Like) GetID() *ObjectID {
 	return Activity(l).GetID()
@@ -1316,6 +1326,11 @@ func (q Question) IsObject() bool {
 	return true
 }
 
+// IsCollection returns false for Question objects
+func (q Question) IsCollection() bool {
+	return false
+}
+
 // IsLink returns false for Question objects
 func (q Question) IsLink() bool {
 	return false

collections.go

@@ -5,7 +5,10 @@ import (
 	"github.com/buger/jsonparser"
 )
 
+const CollectionOfItems ActivityVocabularyType = "ItemCollection"
+
 var CollectionTypes = ActivityVocabularyTypes{
+	CollectionOfItems,
 	CollectionType,
 	OrderedCollectionType,
 	CollectionPageType,
@@ -14,7 +17,7 @@ var CollectionTypes = ActivityVocabularyTypes{
 
 type CollectionInterface interface {
 	ObjectOrLink
-	Collection() CollectionInterface
+	Collection() ItemCollection
 	Append(ob Item) error
 	Count() uint
 	Contains(IRI) bool
@@ -299,25 +302,44 @@ func (o *OrderedCollection) MarshalJSON() ([]byte, error) {
 */
 
 // Collection returns the underlying Collection type
-func (c *Collection) Collection() CollectionInterface {
-	return c
+func (c *Collection) Collection() ItemCollection {
+	return c.Items
+}
+
+// IsCollection returns true for Collection objects
+func (c Collection) IsCollection() bool {
+	return true
 }
 
 // Collection returns the underlying Collection type
-func (o *OrderedCollection) Collection() CollectionInterface {
-	return o
+func (o *OrderedCollection) Collection() ItemCollection {
+	return o.OrderedItems
+}
+
+// IsCollection returns true for OrderedCollection objects
+func (o OrderedCollection) IsCollection() bool {
+	return true
 }
 
 // Collection returns the underlying Collection type
-func (c *CollectionPage) Collection() CollectionInterface {
-	return c
+func (c *CollectionPage) Collection() ItemCollection {
+	return c.Items
+}
+
+// IsCollection returns true for CollectionPage objects
+func (c CollectionPage) IsCollection() bool {
+	return true
 }
 
 // Collection returns the underlying Collection type
-func (o *OrderedCollectionPage) Collection() CollectionInterface {
-	return o
+func (o *OrderedCollectionPage) Collection() ItemCollection {
+	return o.OrderedItems
 }
 
+// IsCollection returns true for OrderedCollectionPage objects
+func (o OrderedCollectionPage) IsCollection() bool {
+	return true
+}
 // FlattenItemCollection flattens the Collection's properties from Object type to IRI
 func FlattenItemCollection(c ItemCollection) ItemCollection {
 	if c != nil && len(c) > 0 {
@@ -328,6 +350,17 @@ func FlattenItemCollection(c ItemCollection) ItemCollection {
 	return c
 }
 
+// ToItemCollection
+func ToItemCollection(it Item) (*ItemCollection, error) {
+	switch i := it.(type) {
+	case *ItemCollection:
+		return i, nil
+	case ItemCollection:
+		return &i, nil
+	}
+	return nil, errors.New("unable to convert to item collection")
+}
+
 // ToCollection
 func ToCollection(it Item) (*Collection, error) {
 	switch i := it.(type) {

collections_test.go

@@ -115,8 +115,8 @@ func TestCollection_Collection(t *testing.T) {
 
 	c := CollectionNew(id)
 
-	if c.Collection() != c {
-		t.Errorf("Collection should return itself %q", *c.GetID())
+	if !reflect.DeepEqual(c.Collection(), c.Items) {
+		t.Errorf("Collection items should be equal %v %v", c.Collection(), c.Items)
 	}
 }
 
@@ -299,10 +299,10 @@ func TestOrderedCollection_Append(t *testing.T) {
 func TestOrderedCollection_Collection(t *testing.T) {
 	id := ObjectID("test")
 
-	c := OrderedCollectionNew(id)
+	o := OrderedCollectionNew(id)
 
-	if c.Collection() != c {
-		t.Errorf("Collection should return itself %q", *c.GetID())
+	if !reflect.DeepEqual(o.Collection(), o.OrderedItems) {
+		t.Errorf("Collection items should be equal %v %v", o.Collection(), o.OrderedItems)
 	}
 }
 
@@ -488,8 +488,8 @@ func TestOrderedCollectionPage_Collection(t *testing.T) {
 	c := OrderedCollectionNew(id)
 	p := OrderedCollectionPageNew(c)
 
-	if p.Collection() != p {
-		t.Errorf("Collection should return itself %q", *p.GetID())
+	if !reflect.DeepEqual(p.Collection(), p.OrderedItems) {
+		t.Errorf("Collection items should be equal %v %v", p.Collection(), p.OrderedItems)
 	}
 }
 
@@ -499,8 +499,8 @@ func TestCollectionPage_Collection(t *testing.T) {
 	c := CollectionNew(id)
 	p := CollectionPageNew(c)
 
-	if p.Collection() != p {
-		t.Errorf("Collection should return itself %q", *p.GetID())
+	if !reflect.DeepEqual(p.Collection(), p.Items) {
+		t.Errorf("Collection items should be equal %v %v", p.Collection(), p.Items)
 	}
 }
 

iri.go

@@ -56,6 +56,11 @@ func (i IRI) IsObject() bool {
 	return false
 }
 
+// IsCollection returns false for IRI objects
+func (i IRI) IsCollection() bool {
+	return false
+}
+
 // FlattenToIRI checks if Item can be flatten to an IRI and returns it if so
 func FlattenToIRI(it Item) Item {
 	if it != nil && it.IsObject() && len(it.GetLink()) > 0 {

item.go

@@ -18,7 +18,7 @@ func (i ItemCollection) GetLink() IRI {
 
 // GetType returns the ItemCollection's type
 func (i ItemCollection) GetType() ActivityVocabularyType {
-	return i.First().GetType()
+	return CollectionOfItems
 }
 
 // IsLink returns false for an ItemCollection object
@@ -58,12 +58,17 @@ func (i ItemCollection) First() Item {
 }
 
 // Collection returns the current object as collection interface
-func (i *ItemCollection) Collection() CollectionInterface {
-	return i
+func (i *ItemCollection) Collection() ItemCollection {
+	return *i
+}
+
+// IsCollection returns true for ItemCollection arrays
+func (i ItemCollection) IsCollection() bool {
+	return true
 }
 
 // Contains verifies if IRIs array contains the received one
-func(i ItemCollection) Contains(r IRI) bool {
+func (i ItemCollection) Contains(r IRI) bool {
 	if len(i) == 0 {
 		return false
 	}

link.go

@@ -74,6 +74,11 @@ func (l Link) IsObject() bool {
 	return l.Type == ObjectType || ObjectTypes.Contains(l.Type)
 }
 
+// IsCollection returns false for Link objects
+func (l Link) IsCollection() bool {
+	return false
+}
+
 // GetID returns the ObjectID corresponding to the Link object
 func (l Link) GetID() *ObjectID {
 	return &l.ID
@@ -99,6 +104,11 @@ func (m Mention) IsObject() bool {
 	return m.Type == ObjectType || ObjectTypes.Contains(m.Type)
 }
 
+// IsCollection returns false for Mention objects
+func (m Mention) IsCollection() bool {
+	return false
+}
+
 // GetID returns the ObjectID corresponding to the Mention object
 func (m Mention) GetID() *ObjectID {
 	return Link(m).GetID()

object.go

@@ -111,11 +111,12 @@ type (
 		LinkOrURI
 		// GetType returns the ActivityStreams type
 		GetType() ActivityVocabularyType
-		// IsLink shows if current object represents a link object or an IRI
+		// IsLink shows if current item represents a Link object or an IRI
 		IsLink() bool
-		// IsObject shows if current object represents an ActivityStrems object
+		// IsObject shows if current item represents an ActivityStreams object
 		IsObject() bool
-		//UnmarshalJSON([]byte) error
+		// IsCollection shows if the current item represents an ItemCollection
+		IsCollection()bool
 	}
 	// Mapper interface allows external objects to implement their own mechanism for loading information
 	// from an ActivityStreams vocabulary object
@@ -193,6 +194,11 @@ func (o Object) IsObject() bool {
 	return true
 }
 
+// IsCollection returns false for Object objects
+func (o Object) IsCollection() bool {
+	return false
+}
+
 // MarshalJSON serializes the NaturalLanguageValues into JSON
 func (n NaturalLanguageValues) MarshalJSON() ([]byte, error) {
 	if len(n) == 0 {