change IIdentifiable interface to use a string instead of int

internal/model/article.go

@@ -8,7 +8,6 @@ import (
 
 // TODO docstring
 type Article struct {
-    Identifier  uint
     SourceUrl   string
     PublishDate time.Time
     FetchDate   time.Time
@@ -21,7 +20,6 @@ type Article struct {
 // Generates a hash based on the source url of the article. Can be used to
 // identify the article.
 func (article *Article) Hash() string {
-
     hash := sha256.Sum256([]byte(article.SourceUrl))
     return hex.EncodeToString(hash[:])
 }
@@ -30,6 +28,6 @@ func (article *Article) Hash() string {
 // --- implement IIdentifiable interface ---
 
 // Using the Identifier attribute as the Id.
-func (article *Article) Id() uint {
-    return article.Identifier
+func (article *Article) Id() string {
+    return article.Hash()
 }