refactor(db): Establish Post->Thread association

This makes it possible to query posts by thread via Diesel.

migrations/2018-04-08-161017_joinable_posts/down.sql

@@ -0,0 +1 @@
+ALTER TABLE posts RENAME COLUMN thread_id TO thread;

migrations/2018-04-08-161017_joinable_posts/up.sql

@@ -0,0 +1 @@
+ALTER TABLE posts RENAME COLUMN thread TO thread_id;

src/db.rs

@@ -47,11 +47,15 @@ impl Handler<GetThread> for DbExecutor {
 
     fn handle(&mut self, msg: GetThread, _: &mut Self::Context) -> Self::Result {
         use schema::threads::dsl::*;
+
         let conn = self.0.get().unwrap();
-        let result: Thread = threads
+        let thread_result: Thread = threads
             .find(msg.0).first(&conn)
             .expect("Error loading thread");
 
-        Ok((result, vec![]))
+        let post_list = Post::belonging_to(&thread_result)
+            .load::<Post>(&conn).expect("Error loading posts for thread");
+
+        Ok((thread_result, post_list))
     }
 }

src/models.rs

@@ -1,6 +1,7 @@
 use chrono::prelude::{DateTime, Utc};
+use schema::{threads, posts};
 
-#[derive(Queryable, Serialize)]
+#[derive(Identifiable, Queryable, Serialize)]
 pub struct Thread {
     pub id: i32,
     pub title: String,
@@ -8,10 +9,11 @@ pub struct Thread {
     pub posted: DateTime<Utc>,
 }
 
-#[derive(Queryable, Serialize)]
+#[derive(Identifiable, Queryable, Serialize, Associations)]
+#[belongs_to(Thread)]
 pub struct Post {
     pub id: i32,
-    pub thread: i32,
+    pub thread_id: i32,
     pub body: String,
     pub posted: DateTime<Utc>,
 }

src/schema.rs

@@ -1,7 +1,7 @@
 table! {
     posts (id) {
         id -> Int4,
-        thread -> Int4,
+        thread_id -> Int4,
         body -> Text,
         posted -> Timestamptz,
     }
@@ -16,7 +16,7 @@ table! {
     }
 }
 
-joinable!(posts -> threads (thread));
+joinable!(posts -> threads (thread_id));
 
 allow_tables_to_appear_in_same_query!(
     posts,