Add migrate & unmigrate core helpers (#250)

.github/workflows/ci.yml

@@ -102,13 +102,18 @@ jobs:
       run: cd butane_codegen && cargo +stable test --all-features
     - name: Test CLI
       run: cd butane_cli && cargo +stable test --all-features
-    - name: Run example cli tests
-      run: cd example && cargo +stable test --all-features
     - name: Test
       run: cd butane && cargo +stable test --all-features
-    - name: Check example migrations
+    - name: Check example migrations have been updated
       run: |
         set -ex
         make regenerate-example-migrations
         git add -A
         git diff --exit-code
+    - name: Run tests in examples
+      run: |
+        cargo +stable test -p example --all-features
+        cd examples
+        for dir in *; do
+          cargo +stable test -p $dir --all-features
+        done

butane/tests/migration-tests.rs

@@ -1,9 +1,8 @@
-use butane::migrations::{
-    adb::DeferredSqlType, adb::TypeIdentifier, adb::TypeKey, MemMigrations, Migration,
-    MigrationMut, Migrations, MigrationsMut,
-};
-use butane::{db::Connection, prelude::*, SqlType, SqlVal};
 use butane_core::codegen::{butane_type_with_migrations, model_with_migrations};
+use butane_core::db::{BackendConnection, Connection};
+use butane_core::migrations::adb::{DeferredSqlType, TypeIdentifier, TypeKey};
+use butane_core::migrations::{MemMigrations, Migration, MigrationMut, Migrations, MigrationsMut};
+use butane_core::{SqlType, SqlVal};
 #[cfg(feature = "pg")]
 use butane_test_helper::pg_connection;
 #[cfg(feature = "sqlite")]
@@ -343,18 +342,21 @@ fn test_migrate(
         .create_migration(&backends, "v2", ms.latest().as_ref())
         .unwrap());
 
-    let mut to_apply = ms.unapplied_migrations(conn).unwrap();
+    let to_apply = ms.unapplied_migrations(conn).unwrap();
     assert_eq!(to_apply.len(), 2);
-    for m in &to_apply {
-        m.apply(conn).unwrap();
-    }
+
+    ms.migrate(conn).unwrap();
+
+    let to_apply = ms.unapplied_migrations(conn).unwrap();
+    assert_eq!(to_apply.len(), 0);
+
     verify_sql(conn, &ms, expected_up_sql, expected_down_sql);
 
     // Now downgrade, just to make sure we can
-    to_apply.reverse();
-    for m in to_apply {
-        m.downgrade(conn).unwrap();
-    }
+    ms.unmigrate(conn).unwrap();
+
+    let to_apply = ms.unapplied_migrations(conn).unwrap();
+    assert_eq!(to_apply.len(), 2);
 }
 
 fn verify_sql(
@@ -559,16 +561,19 @@ fn migration_delete_table(conn: &mut Connection, expected_up_sql: &str, expected
         .create_migration(&backends, "v2", ms.latest().as_ref())
         .unwrap());
 
-    let mut to_apply = ms.unapplied_migrations(conn).unwrap();
+    let to_apply = ms.unapplied_migrations(conn).unwrap();
     assert_eq!(to_apply.len(), 2);
-    for m in &to_apply {
-        m.apply(conn).unwrap();
-    }
+
+    ms.migrate(conn).unwrap();
+
+    let to_apply = ms.unapplied_migrations(conn).unwrap();
+    assert_eq!(to_apply.len(), 0);
+
     verify_sql(conn, &ms, expected_up_sql, expected_down_sql);
 
     // Now downgrade, just to make sure we can
-    to_apply.reverse();
-    for m in to_apply {
-        m.downgrade(conn).unwrap();
-    }
+    ms.unmigrate(conn).unwrap();
+
+    let to_apply = ms.unapplied_migrations(conn).unwrap();
+    assert_eq!(to_apply.len(), 2);
 }

butane_core/src/migrations/mod.rs

@@ -8,7 +8,7 @@ use std::path::Path;
 use fallible_iterator::FallibleIterator;
 use nonempty::NonEmpty;
 
-use crate::db::BackendRows;
+use crate::db::{BackendConnection, BackendRows};
 use crate::db::{Column, ConnectionMethods};
 use crate::sqlval::{FromSql, SqlValRef, ToSql};
 use crate::{db, query, DataObject, DataResult, Error, PrimaryKeyType, Result, SqlType};
@@ -109,6 +109,34 @@ pub trait Migrations {
         }
         Ok(None)
     }
+
+    /// Migrate connection forward.
+    fn migrate(&self, connection: &mut impl BackendConnection) -> Result<()> {
+        let to_apply = self.unapplied_migrations(connection)?;
+        for migration in &to_apply {
+            crate::info!("Applying migration {}", migration.name());
+            migration.apply(connection)?;
+        }
+        Ok(())
+    }
+
+    /// Remove all applied migrations.
+    fn unmigrate(&self, connection: &mut impl BackendConnection) -> Result<()> {
+        let mut migration = match self.last_applied_migration(connection)? {
+            Some(migration) => migration,
+            None => return Ok(()),
+        };
+        migration.downgrade(connection)?;
+
+        while let Ok(Some(migration_name)) = migration.migration_from() {
+            migration = self
+                .get_migration(&migration_name)
+                .ok_or(Error::MigrationError("Migration not in chain".to_string()))?;
+            crate::info!("Rolling back migration {}", migration.name());
+            migration.downgrade(connection)?;
+        }
+        Ok(())
+    }
 }
 
 /// Extension of [`Migrations`] to modify the series of migrations.

butane_test_helper/src/lib.rs

@@ -209,11 +209,7 @@ pub fn setup_db(backend: Box<dyn Backend>, conn: &mut Connection, migrate: bool)
         "expected to create migration"
     );
     log::info!("created current migration");
-    let to_apply = mem_migrations.unapplied_migrations(conn).unwrap();
-    for m in to_apply {
-        log::info!("Applying migration {}", m.name());
-        m.apply(conn).unwrap();
-    }
+    mem_migrations.migrate(conn).unwrap();
 }
 
 /// Create a sqlite [`Connection`].

docs/getting-started.md

@@ -505,14 +505,11 @@ to use these migrations:
 
 ``` rust
 pub fn establish_connection() -> Connection {
-    use butane::migrations::{Migration, Migrations};
+    use butane::migrations::Migrations;
 
     let mut connection = butane::db::connect(&ConnectionSpec::load(".butane/connection.json").unwrap()).unwrap();
     let migrations = butane_migrations::get_migrations().unwrap();
-    let to_apply = migrations.unapplied_migrations(&connection).unwrap();
-    for migration in to_apply {
-        migration.apply(&mut connection).unwrap();
-    }
+    migrations.migrate(&mut connection).unwrap();
     connection
 }
 ```

examples/getting_started/src/lib.rs

@@ -6,7 +6,7 @@ pub mod butane_migrations;
 pub mod models;
 
 use butane::db::{Connection, ConnectionSpec};
-use butane::migrations::{Migration, Migrations};
+use butane::migrations::Migrations;
 use butane::prelude::*;
 use models::{Blog, Post};
 
@@ -15,10 +15,7 @@ pub fn establish_connection() -> Connection {
     let mut connection =
         butane::db::connect(&ConnectionSpec::load(".butane/connection.json").unwrap()).unwrap();
     let migrations = butane_migrations::get_migrations().unwrap();
-    let to_apply = migrations.unapplied_migrations(&connection).unwrap();
-    for migration in to_apply {
-        migration.apply(&mut connection).unwrap();
-    }
+    migrations.migrate(&mut connection).unwrap();
     connection
 }
 

examples/getting_started/tests/rollback.rs

@@ -1,5 +1,5 @@
 use butane::db::{BackendConnection, Connection};
-use butane::migrations::{Migration, Migrations};
+use butane::migrations::Migrations;
 use butane::DataObject;
 use butane_test_helper::*;
 
@@ -38,22 +38,12 @@ fn migrate_and_rollback(mut connection: Connection) {
     // Migrate forward.
     let base_dir = std::path::PathBuf::from(".butane");
     let migrations = butane_cli::get_migrations(&base_dir).unwrap();
-    let to_apply = migrations.unapplied_migrations(&connection).unwrap();
-    for migration in &to_apply {
-        migration
-            .apply(&mut connection)
-            .unwrap_or_else(|err| panic!("migration {} failed: {err}", migration.name()));
-        eprintln!("Applied {}", migration.name());
-    }
+
+    migrations.migrate(&mut connection).unwrap();
 
     insert_data(&connection);
 
     // Rollback migrations.
-    for migration in to_apply.iter().rev() {
-        migration
-            .downgrade(&mut connection)
-            .unwrap_or_else(|err| panic!("rollback of {} failed: {err}", migration.name()));
-        eprintln!("Rolled back {}", migration.name());
-    }
+    migrations.unmigrate(&mut connection).unwrap();
 }
 testall_no_migrate!(migrate_and_rollback);

examples/newtype/src/lib.rs

@@ -6,7 +6,7 @@ pub mod butane_migrations;
 pub mod models;
 
 use butane::db::{Connection, ConnectionSpec};
-use butane::migrations::{Migration, Migrations};
+use butane::migrations::Migrations;
 use butane::prelude::*;
 use models::{Blog, Post};
 
@@ -15,10 +15,7 @@ pub fn establish_connection() -> Connection {
     let mut connection =
         butane::db::connect(&ConnectionSpec::load(".butane/connection.json").unwrap()).unwrap();
     let migrations = butane_migrations::get_migrations().unwrap();
-    let to_apply = migrations.unapplied_migrations(&connection).unwrap();
-    for migration in to_apply {
-        migration.apply(&mut connection).unwrap();
-    }
+    migrations.migrate(&mut connection).unwrap();
     connection
 }
 

examples/newtype/tests/rollback.rs

@@ -32,12 +32,8 @@ fn migrate_and_rollback(mut connection: Connection) {
     let base_dir = std::path::PathBuf::from(".butane");
     let migrations = butane_cli::get_migrations(&base_dir).unwrap();
     let to_apply = migrations.unapplied_migrations(&connection).unwrap();
-    for migration in &to_apply {
-        migration
-            .apply(&mut connection)
-            .unwrap_or_else(|err| panic!("migration {} failed: {err}", migration.name()));
-        eprintln!("Applied {}", migration.name());
-    }
+
+    migrations.migrate(&mut connection).unwrap();
 
     insert_data(&connection);