Merge pull request diesel-rs#991 from diesel-rs/sg-default-migrations

Don't magically set up timestamp helpers, create a migration file

Author: sgrif

CHANGELOG.md

@@ -61,6 +61,9 @@ for Rust libraries in [RFC #1105](https://github.com/rust-lang/rfcs/blob/master/
 * Trait bounds along the lines of `T: LoadDsl<Conn>, U: Queryable<T::SqlType,
   Conn::Backend>` should be changed to `T: LoadQuery<Conn, U>`.
 
+* Diesel now uses a migration to set up its timestamp helpers. To generate this
+  migration for your project, run `diesel database setup`.
+
 ### Removed
 
 * `#[has_many]` has been removed. Its functionality is now provided by

diesel/src/connection/mod.rs

@@ -148,5 +148,4 @@ pub trait Connection: SimpleConnection + Sized + Send {
 
     #[doc(hidden)] fn silence_notices<F: FnOnce() -> T, T>(&self, f: F) -> T;
     #[doc(hidden)] fn transaction_manager(&self) -> &Self::TransactionManager;
-    #[doc(hidden)] fn setup_helper_functions(&self);
 }

diesel/src/migrations/mod.rs

@@ -203,7 +203,6 @@ fn migration_with_version(migrations_dir: &Path, ver: &str) -> Result<Box<Migrat
 
 #[doc(hidden)]
 pub fn setup_database<Conn: Connection>(conn: &Conn) -> QueryResult<usize> {
-    conn.setup_helper_functions();
     create_schema_migrations_table_if_needed(conn)
 }
 

diesel/src/mysql/connection/mod.rs

@@ -97,11 +97,6 @@ impl Connection for MysqlConnection {
     fn transaction_manager(&self) -> &Self::TransactionManager {
         &self.transaction_manager
     }
-
-    #[doc(hidden)]
-    fn setup_helper_functions(&self) {
-        // FIXME: We can implement this pretty easily
-    }
 }
 
 impl MysqlConnection {

diesel/src/pg/connection/mod.rs

@@ -95,13 +95,6 @@ impl Connection for PgConnection {
     fn transaction_manager(&self) -> &Self::TransactionManager {
         &self.transaction_manager
     }
-
-    #[doc(hidden)]
-    fn setup_helper_functions(&self) {
-        self.batch_execute(
-            include_str!("setup/timestamp_helpers.sql")
-        ).expect("Error creating timestamp helper functions for Pg");
-    }
 }
 
 impl PgConnection {

diesel/src/pg/connection/setup/timestamp_helpers.sql

@@ -92,11 +92,6 @@ impl Connection for SqliteConnection {
     fn transaction_manager(&self) -> &Self::TransactionManager {
         &self.transaction_manager
     }
-
-    #[doc(hidden)]
-    fn setup_helper_functions(&self) {
-        // this will be implemented at least when timestamps are supported in SQLite
-    }
 }
 
 impl SqliteConnection {

diesel/src/sqlite/connection/mod.rs

@@ -18,6 +18,10 @@ use std::error::Error;
 use std::env;
 use std::io::stdout;
 use std::path::Path;
+#[cfg(feature="postgres")]
+use std::fs::{self, File};
+#[cfg(feature="postgres")]
+use std::io::Write;
 
 enum Backend {
     #[cfg(feature="postgres")]
@@ -116,8 +120,10 @@ pub fn reset_database(args: &ArgMatches, migrations_dir: &Path) -> DatabaseResul
 pub fn setup_database(args: &ArgMatches, migrations_dir: &Path) -> DatabaseResult<()> {
     let database_url = database_url(args);
 
-    try!(create_database_if_needed(&database_url));
-    create_schema_table_and_run_migrations_if_needed(&database_url, migrations_dir)
+    create_database_if_needed(&database_url)?;
+    create_default_migration_if_needed(&database_url, migrations_dir)?;
+    create_schema_table_and_run_migrations_if_needed(&database_url, migrations_dir)?;
+    Ok(())
 }
 
 pub fn drop_database_command(args: &ArgMatches) -> DatabaseResult<()> {
@@ -158,6 +164,31 @@ fn create_database_if_needed(database_url: &str) -> DatabaseResult<()> {
     Ok(())
 }
 
+fn create_default_migration_if_needed(database_url: &str, migrations_dir: &Path)
+    -> DatabaseResult<()>
+{
+    let initial_migration_path = migrations_dir.join("00000000000000_diesel_initial_setup");
+    if initial_migration_path.exists() {
+        return Ok(())
+    }
+
+    #[allow(unreachable_patterns)]
+    #[cfg_attr(feature="clippy", allow(single_match))]
+    match Backend::for_url(database_url) {
+        #[cfg(feature="postgres")]
+        Backend::Pg => {
+            fs::create_dir_all(&initial_migration_path)?;
+            let mut up_sql = File::create(initial_migration_path.join("up.sql"))?;
+            up_sql.write_all(include_bytes!("setup_sql/postgres/initial_setup/up.sql"))?;
+            let mut down_sql = File::create(initial_migration_path.join("down.sql"))?;
+            down_sql.write_all(include_bytes!("setup_sql/postgres/initial_setup/down.sql"))?;
+        }
+        _ => {} // No default migration for this backend
+    }
+
+    Ok(())
+}
+
 /// Creates the `__diesel_schema_migrations` table if it doesn't exist. If the
 /// table didn't exist, it also runs any pending migrations. Returns a
 /// `DatabaseError::ConnectionError` if it can't create the table, and exits

diesel_cli/src/database.rs

@@ -0,0 +1,2 @@
+DROP FUNCTION IF EXISTS diesel_manage_updated_at(_tbl regclass);
+DROP FUNCTION IF EXISTS diesel_set_updated_at();

diesel_cli/src/setup_sql/postgres/initial_setup/down.sql

@@ -0,0 +1,36 @@
+-- This file was automatically created by Diesel to setup helper functions
+-- and other internal bookkeeping. This file is safe to edit, any future
+-- changes will be added to existing projects as new migrations.
+
+
+
+
+-- Sets up a trigger for the given table to automatically set a column called
+-- `updated_at` whenever the row is modified (unless `updated_at` was included
+-- in the modified columns)
+--
+-- # Example
+--
+-- ```sql
+-- CREATE TABLE users (id SERIAL PRIMARY KEY, updated_at TIMESTAMP NOT NULL DEFAULT NOW());
+--
+-- SELECT diesel_manage_updated_at('users');
+-- ```
+CREATE OR REPLACE FUNCTION diesel_manage_updated_at(_tbl regclass) RETURNS VOID AS $$
+BEGIN
+    EXECUTE format('CREATE TRIGGER set_updated_at BEFORE UPDATE ON %s
+                    FOR EACH ROW EXECUTE PROCEDURE diesel_set_updated_at()', _tbl);
+END;
+$$ LANGUAGE plpgsql;
+
+CREATE OR REPLACE FUNCTION diesel_set_updated_at() RETURNS trigger AS $$
+BEGIN
+    IF (
+        NEW IS DISTINCT FROM OLD AND
+        NEW.updated_at IS NOT DISTINCT FROM OLD.updated_at
+    ) THEN
+        NEW.updated_at := current_timestamp;
+    END IF;
+    RETURN NEW;
+END;
+$$ LANGUAGE plpgsql;