Merge rust-lang#898

898: Port `bin/delete-version` to use Diesel r=carols10cents

The changes here were broadly similar to those in `delete-crate`. The
child row deletions are no longer needed here, as they cascade in the
database. (Arguably neither of these binaries are really needed anymore
since it can just be done in the database)

Author: bors-voyager[bot]

src/bin/delete-version.rs

@@ -8,28 +8,29 @@
 #![deny(warnings)]
 
 extern crate cargo_registry;
-extern crate postgres;
+extern crate diesel;
 extern crate time;
 extern crate semver;
 
+use diesel::prelude::*;
+use diesel::pg::PgConnection;
 use std::env;
 use std::io;
 use std::io::prelude::*;
 
 use cargo_registry::{Crate, Version};
+use cargo_registry::schema::versions;
 
 #[allow(dead_code)]
 fn main() {
-    let conn = cargo_registry::db::connect_now_old();
-    {
-        let tx = conn.transaction().unwrap();
-        delete(&tx);
-        tx.set_commit();
-        tx.finish().unwrap();
-    }
+    let conn = cargo_registry::db::connect_now().unwrap();
+    conn.transaction::<_, diesel::result::Error, _>(|| {
+        delete(&conn);
+        Ok(())
+    }).unwrap()
 }
 
-fn delete(tx: &postgres::transaction::Transaction) {
+fn delete(conn: &PgConnection) {
     let name = match env::args().nth(1) {
         None => {
             println!("needs a crate-name argument");
@@ -44,11 +45,11 @@ fn delete(tx: &postgres::transaction::Transaction) {
         }
         Some(s) => s,
     };
-    let version = semver::Version::parse(&version).unwrap();
 
-    let krate = Crate::find_by_name(tx, &name).unwrap();
-    let v = Version::find_by_num(tx, krate.id, &version)
-        .unwrap()
+    let krate = Crate::by_name(&name).first::<Crate>(conn).unwrap();
+    let v = Version::belonging_to(&krate)
+        .filter(versions::num.eq(&version))
+        .first::<Version>(conn)
         .unwrap();
     print!(
         "Are you sure you want to delete {}#{} ({}) [y/N]: ",
@@ -64,20 +65,8 @@ fn delete(tx: &postgres::transaction::Transaction) {
     }
 
     println!("deleting version {} ({})", v.num, v.id);
-    let n = tx.execute(
-        "DELETE FROM version_downloads WHERE version_id = $1",
-        &[&v.id],
-    ).unwrap();
-    println!("  {} download records deleted", n);
-    let n = tx.execute(
-        "DELETE FROM version_authors WHERE version_id = $1",
-        &[&v.id],
-    ).unwrap();
-    println!("  {} author records deleted", n);
-    let n = tx.execute("DELETE FROM dependencies WHERE version_id = $1", &[&v.id])
-        .unwrap();
-    println!("  {} dependencies deleted", n);
-    tx.execute("DELETE FROM versions WHERE id = $1", &[&v.id])
+    diesel::delete(versions::table.find(&v.id))
+        .execute(conn)
         .unwrap();
 
     print!("commit? [y/N]: ");