Refactored the whole code to a better structure

project/src/db_connection.rs

@@ -0,0 +1,15 @@
+use diesel::r2d2::{ConnectionManager, Pool, PoolError, PooledConnection};
+use diesel::MysqlConnection;
+
+pub type DbPool = r2d2::Pool<ConnectionManager<MysqlConnection>>;
+pub type MyPooledConnection = PooledConnection<ConnectionManager<MysqlConnection>>;
+
+fn init_pool(database_url: &str) -> Result<DbPool, PoolError> {
+    let manager = ConnectionManager::<MysqlConnection>::new(database_url);
+    Pool::builder().build(manager)
+}
+
+pub fn get_pool() -> DbPool {
+    let connspec = std::env::var("DATABASE_URL").expect("DATABASE_URL");
+    init_pool(&connspec).expect("Failed to create DB pool")
+}