add viewmodel for article

internal/model/Article.go

@@ -0,0 +1,33 @@
+package model
+
+import (
+    "time"
+    "crypto/sha256"
+    "encoding/hex"
+)
+
+// TODO docstring
+type Article struct {
+    SourceUrl   string
+    PublishDate time.Time
+    FetchDate   time.Time
+    Title       string
+    Content     string
+    Author      string
+}
+
+
+// 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[:])
+}
+
+
+// --- implement IIdentifiable interface ---
+
+// Using the Identifier attribute as the Id.
+func (article *Article) Id() string {
+    return article.Hash()
+}