refac: add additional trait for migration names

migra-cli/src/commands/downgrade.rs

@@ -1,6 +1,6 @@
 use crate::config::Config;
 use crate::database::PostgresConnection;
-use crate::migration::{DatabaseMigrationManager, MigrationManager};
+use crate::migration::{DatabaseMigrationManager, MigrationManager, MigrationNames};
 use crate::StdResult;
 use std::convert::TryFrom;
 

migra-cli/src/commands/list.rs

@@ -3,6 +3,7 @@ use crate::database::{DatabaseConnection, PostgresConnection};
 use crate::error::{ErrorKind, StdResult};
 use crate::migration::{
     filter_pending_migrations, DatabaseMigrationManager, Migration, MigrationManager,
+    MigrationNames,
 };
 
 const EM_DASH: char = '—';

migra-cli/src/commands/upgrade.rs

@@ -1,6 +1,8 @@
-use crate::database::{DatabaseConnection, PostgresConnection};
-use crate::migration::Migration;
-use crate::migration::{filter_pending_migrations, DatabaseMigrationManager, MigrationManager};
+use crate::database::PostgresConnection;
+use crate::migration::{
+    filter_pending_migrations, DatabaseMigrationManager, Migration, MigrationManager,
+    MigrationNames,
+};
 use crate::Config;
 use crate::StdResult;
 use std::convert::TryFrom;
@@ -25,13 +27,12 @@ fn is_up_to_date_migrations(migrations: &[Migration], applied_migration_names: &
     migrations.is_empty() || migrations.last().map(|m| m.name()) == applied_migration_names.first()
 }
 
-fn upgrade_all_pending_migrations<Conn, ManagerT>(
+fn upgrade_all_pending_migrations<ManagerT>(
     mut manager: ManagerT,
     pending_migrations: &[Migration],
 ) -> StdResult<()>
 where
-    Conn: DatabaseConnection,
-    ManagerT: Sized + DatabaseMigrationManager<Conn>,
+    ManagerT: Sized + DatabaseMigrationManager,
 {
     for migration in pending_migrations.iter() {
         println!("upgrade {}...", migration.name());

migra-cli/src/database.rs

@@ -17,6 +17,13 @@ pub trait TryFromSql<QueryResultRow>: Sized {
     fn try_from_sql(row: QueryResultRow) -> StdResult<Self>;
 }
 
+impl TryFromSql<postgres::Row> for String {
+    fn try_from_sql(row: postgres::Row) -> StdResult<Self> {
+        let res: String = row.get(0);
+        Ok(res)
+    }
+}
+
 pub trait DatabaseConnection: Sized {
     type QueryResultRow;
     type QueryResult;

migra-cli/src/migration.rs

@@ -1,4 +1,3 @@
-use crate::database::TryFromSql;
 use crate::database::{DatabaseConnection, PostgresConnection};
 use crate::path::PathBuilder;
 use crate::StdResult;
@@ -67,14 +66,7 @@ pub fn is_migrations_table_not_found<D: std::fmt::Display>(error: D) -> bool {
         .contains(r#"relation "migrations" does not exist"#)
 }
 
-impl TryFromSql<postgres::Row> for String {
-    fn try_from_sql(row: postgres::Row) -> StdResult<Self> {
-        let res: String = row.get(0);
-        Ok(res)
-    }
-}
-
-pub trait DatabaseMigrationManager<Conn: DatabaseConnection> {
+pub trait DatabaseMigrationManager {
     const CREATE_MIGRATIONS_STMT: &'static str = r#"
         CREATE TABLE IF NOT EXISTS migrations (
             id      serial      PRIMARY KEY,
@@ -88,8 +80,6 @@ pub trait DatabaseMigrationManager<Conn: DatabaseConnection> {
 
     fn apply_sql(&mut self, sql_content: &str) -> StdResult<()>;
 
-    fn applied_migration_names(&mut self) -> StdResult<Vec<String>>;
-
     fn create_migrations_table(&mut self) -> StdResult<()>;
 
     fn insert_migration_info(&mut self, name: &str) -> StdResult<u64>;
@@ -116,26 +106,14 @@ pub trait DatabaseMigrationManager<Conn: DatabaseConnection> {
     }
 }
 
-impl DatabaseMigrationManager<PostgresConnection> for MigrationManager<PostgresConnection> {
+impl<Conn> DatabaseMigrationManager for MigrationManager<Conn>
+where
+    Conn: DatabaseConnection,
+{
     fn apply_sql(&mut self, sql_content: &str) -> StdResult<()> {
         self.conn.batch_execute(sql_content)
     }
 
-    fn applied_migration_names(&mut self) -> StdResult<Vec<String>> {
-        let res = self
-            .conn
-            .query("SELECT name FROM migrations ORDER BY id DESC", &[])
-            .or_else(|e| {
-                if is_migrations_table_not_found(&e) {
-                    Ok(Vec::new())
-                } else {
-                    Err(e)
-                }
-            })?;
-
-        Ok(res.into_iter().collect())
-    }
-
     fn create_migrations_table(&mut self) -> StdResult<()> {
         self.conn.batch_execute(Self::CREATE_MIGRATIONS_STMT)
     }
@@ -149,6 +127,29 @@ impl DatabaseMigrationManager<PostgresConnection> for MigrationManager<PostgresC
     }
 }
 
+pub trait MigrationNames {
+    const APPLIED_MIGRATIONS_STMT: &'static str = "SELECT name FROM migrations ORDER BY id DESC";
+
+    fn applied_migration_names(&mut self) -> StdResult<Vec<String>>;
+}
+
+impl MigrationNames for MigrationManager<PostgresConnection> {
+    fn applied_migration_names(&mut self) -> StdResult<Vec<String>> {
+        let res = self
+            .conn
+            .query(Self::APPLIED_MIGRATIONS_STMT, &[])
+            .or_else(|e| {
+                if is_migrations_table_not_found(&e) {
+                    Ok(Vec::new())
+                } else {
+                    Err(e)
+                }
+            })?;
+
+        Ok(res.into_iter().collect())
+    }
+}
+
 pub fn filter_pending_migrations(
     migrations: Vec<Migration>,
     applied_migration_names: &[String],