Merge pull request #4 from KowalskiPiotr98/initial-migrations-handling

Fix initial migration handling

Author: KowalskiPiotr98

README.md

@@ -21,7 +21,7 @@ You can execute migrations by calling the `Migrate` method in the `migrations` p
 
 There are a couple of important things to remember:
 1. You should store your migrations in a file with `.sql` extension. These files should be contained in a folder called `sql`. The files should have names consisting of a single number, starting at 0 and going **SEQUENTIALLY** up (as in `0.sql`, `1.sql`, `2.sql`...). If you need to remove a migration after a next number has been used, leave the file empty instead of removing it.
-2. Your database model must, from the very beginning, include a migrations table (it **MUST** be created in your `0.sql` migration file). By default, it should contain a single integer column called `id` as a primary key. Note that this behaviour can be modified or adjusted to a different DBMS by overwriting the `MigrationCreator` and `LatestMigrationSelectorSql` variables of the `migrations` package.
+2. Your database model must, from the very beginning, include a migrations table (it **MUST** be created in your `0.sql` migration file). By default, it should contain a single integer column called `id` as a primary key. Note that this behaviour can be modified or adjusted to a different DBMS by overwriting the `MigrationCreator`, `IsInitialMigrationError` and `LatestMigrationSelectorSql` variables of the `migrations` package.
 3. The interface for providing database migrations files must be implemented, as there's no default implementation. You can, however, use the `embed.FS` struct, as it fulfills the conditions of this interface. See below for more details.
 
 #### Usage of `embed.FS` as migration provider

migrations/runner.go

@@ -3,6 +3,7 @@ package migrations
 import (
 	"fmt"
 	database "github.com/KowalskiPiotr98/gotabase"
+	"strings"
 )
 
 var (
@@ -15,12 +16,18 @@ var (
 			currentMigration)
 	}
 	LatestMigrationSelectorSql = "select id from migrations order by id desc limit 1"
+	IsInitialMigrationError    = func(err error) bool {
+		return strings.HasPrefix(err.Error(), "pq: relation") && strings.HasSuffix(err.Error(), "does not exist")
+	}
 )
 
 func Migrate(connector database.Connector, fileProvider MigrationFileProvider) error {
 	latestApplied, err := getLatestAppliedMigration(connector)
 	if err != nil {
-		return err
+		if !IsInitialMigrationError(err) {
+			return err
+		}
+		latestApplied = -1
 	}
 
 	latestAvailable, err := getLatestAvailableMigration(fileProvider)