create db functions to get/set messages

src/db.rs

@@ -74,4 +74,53 @@ impl DB {
                 .unwrap(),
         }
     }
+
+    pub async fn get_message(&mut self, chatid: i64, messageid: i32) -> Result<Option<Message>, Box<dyn std::error::Error>> {
+        use self::schema::messages::dsl::*;
+        let conn = &mut self.pool.get().await.unwrap();
+
+        let msg = messages
+            .filter(chat_id.eq(chatid))
+            .filter(message_id.eq(messageid as i64))
+            .first::<Message>(conn)
+            .await
+            .optional()?;
+
+        Ok(msg)
+    }
+
+    pub async fn get_message_literal(&mut self, chatid: i64, messageid: i32) -> Result<Option<String>, Box<dyn std::error::Error>> {
+        let msg = self.get_message(chatid, messageid).await?;
+        Ok(msg.map(|m| m.token))
+    }
+
+    pub async fn set_message_literal(&mut self, chatid: i64, messageid: i32, literal: &str) -> Result<(), Box<dyn std::error::Error>> {
+        use self::schema::messages::dsl::*;
+        let conn = &mut self.pool.get().await?;
+        
+        let msg = self.clone().get_message(chatid, messageid).await?;
+
+        match msg {
+            Some(msg) => {
+                diesel::update(messages)
+                    .filter(id.eq(msg.id))
+                    .set(token.eq(literal))
+                    .execute(conn)
+                    .await?;
+            },
+            None => {
+                diesel::insert_into(messages)
+                    .values((
+                        chat_id.eq(chatid),
+                        message_id.eq(messageid as i64),
+                        token.eq(literal)
+                    ))
+                    .execute(conn)
+                    .await?;
+            }
+        };
+
+
+        Ok(())
+    }
 }