Create Notification model struct.

src/model/mod.rs

-pub mod subscriber;
+pub mod subscriber;
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+pub mod notification;
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src/model/notification.rs

+use std::fmt::{Display, Formatter, Result};
+
+use rocket::serde::{Deserialize, Serialize};
+
+#[derive(Debug, Clone, Deserialize, Serialize)]
+#[serde(crate = "rocket::serde")]
+pub struct Notification {
+    pub product_title: String,
+    pub product_url: String,
+    pub product_type: String,
+    pub subscriber_name: String,
+    pub status: String
+}
+
+impl Display for Notification {
+    fn fmt(&self, f: &mut Formatter<'_>) -> Result {
+        if self.status.to_uppercase().eq("CREATED") {
+            write!(f,
+                "Hello {}, let's try our new {} product: {}, only in BambangShop! Check it out: {}",
+                self.subscriber_name, self.product_type.to_lowercase(), self.product_title, self.product_url)
+        } else if self.status.to_uppercase().eq("DELETED") {
+            write!(f,
+                "Hello {}, we informed that our {} product called {} already sold out...",
+                self.subscriber_name, self.product_type.to_lowercase(), self.product_title)
+        } else {
+            write!(f,
+                "Hello {}, let's try our {} product: {}, grab it out before the stock ran out! Check it out: {}",
+                self.subscriber_name, self.product_type.to_lowercase(), self.product_title, self.product_url)
+        }
+    }
+}
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