Add relation between posts and authors

migrations/2018-04-23-142746_create_post_authors/down.sql

@@ -0,0 +1,2 @@
+-- This file should undo anything in `up.sql`
+DROP TABLE post_authors;

migrations/2018-04-23-142746_create_post_authors/up.sql

@@ -0,0 +1,6 @@
+-- Your SQL goes here
+CREATE TABLE post_authors (
+    id SERIAL PRIMARY KEY,
+    post_id INTEGER REFERENCES posts(id) ON DELETE CASCADE NOT NULL,
+    author_id INTEGER REFERENCES users(id) ON DELETE CASCADE NOT NULL
+)

src/models/mod.rs

@@ -1,5 +1,6 @@
 pub mod blog_authors;
 pub mod blogs;
 pub mod instance;
+pub mod post_authors;
 pub mod post;
 pub mod user;

src/models/post_authors.rs

@@ -0,0 +1,34 @@
+use diesel;
+use diesel::{PgConnection, QueryDsl, RunQueryDsl, ExpressionMethods};
+use schema::post_authors;
+
+#[derive(Queryable, Identifiable)]
+pub struct PostAuthor {
+    pub id: i32,
+    pub post_id: i32,
+    pub author_id: i32
+}
+
+#[derive(Insertable)]
+#[table_name = "post_authors"]
+pub struct NewPostAuthor {
+    pub post_id: i32,
+    pub author_id: i32
+}
+
+impl PostAuthor {
+    pub fn insert (conn: &PgConnection, new: NewPostAuthor) -> PostAuthor {
+        diesel::insert_into(post_authors::table)
+            .values(new)
+            .get_result(conn)
+            .expect("Error saving new blog author")
+    }
+
+    pub fn get(conn: &PgConnection, id: i32) -> Option<PostAuthor> {
+        post_authors::table.filter(post_authors::id.eq(id))
+            .limit(1)
+            .load::<PostAuthor>(conn)
+            .expect("Error loading blog author by id")
+            .into_iter().nth(0)
+    }
+}

src/schema.rs

@@ -30,6 +30,14 @@ table! {
     }
 }
 
+table! {
+    post_authors (id) {
+        id -> Int4,
+        post_id -> Int4,
+        author_id -> Int4,
+    }
+}
+
 table! {
     posts (id) {
         id -> Int4,
@@ -60,6 +68,8 @@ table! {
 joinable!(blog_authors -> blogs (blog_id));
 joinable!(blog_authors -> users (author_id));
 joinable!(blogs -> instances (instance_id));
+joinable!(post_authors -> posts (post_id));
+joinable!(post_authors -> users (author_id));
 joinable!(posts -> blogs (blog_id));
 joinable!(users -> instances (instance_id));
 
@@ -67,6 +77,7 @@ allow_tables_to_appear_in_same_query!(
     blog_authors,
     blogs,
     instances,
+    post_authors,
     posts,
     users,
 );