Initial commit

errors.go

@@ -0,0 +1,8 @@
+package sqliteutil
+
+import "github.com/mattn/go-sqlite3"
+
+func ErrIsConstraint(err error) bool {
+	e, ok := err.(sqlite3.Error)
+	return ok && e.Code == 19
+}

migrate.go

@@ -0,0 +1,82 @@
+package sqliteutil
+
+import (
+	"database/sql"
+	"embed"
+	"errors"
+	"fmt"
+	"path/filepath"
+	"sort"
+)
+
+const initMigrationTableQuery = `
+CREATE TABLE IF NOT EXISTS migrations(filename TEXT NOT NULL PRIMARY KEY);`
+
+const insertMigrationQuery = `INSERT INTO migrations(filename) VALUES($1)`
+
+const checkMigrationAppliedQuery = `SELECT EXISTS(SELECT 1 FROM migrations WHERE filename=$1)`
+
+func Migrate(db *sql.DB, migrationFS embed.FS) error {
+	return WithTx(db, func(tx *sql.Tx) error {
+		if _, err := tx.Exec(initMigrationTableQuery); err != nil {
+			return err
+		}
+
+		dirs, err := migrationFS.ReadDir(".")
+		if err != nil {
+			return err
+		}
+		if len(dirs) != 1 {
+			return errors.New("expected a single migrations directory")
+		}
+
+		if !dirs[0].IsDir() {
+			return fmt.Errorf("unexpected non-directory in migration FS: %s", dirs[0].Name())
+		}
+
+		dirName := dirs[0].Name()
+		files, err := migrationFS.ReadDir(dirName)
+		if err != nil {
+			return err
+		}
+
+		// Sort sql files by name.
+		sort.Slice(files, func(i, j int) bool {
+			return files[i].Name() < files[j].Name()
+		})
+
+		for _, dirEnt := range files {
+			if !dirEnt.Type().IsRegular() {
+				return fmt.Errorf("unexpected non-regular file in migration fs: %s", dirEnt.Name())
+			}
+
+			var (
+				name   = dirEnt.Name()
+				exists bool
+			)
+
+			err := tx.QueryRow(checkMigrationAppliedQuery, name).Scan(&exists)
+			if err != nil {
+				return err
+			}
+
+			if exists {
+				continue
+			}
+
+			migration, err := migrationFS.ReadFile(filepath.Join(dirName, name))
+			if err != nil {
+				return err
+			}
+
+			if _, err := tx.Exec(string(migration)); err != nil {
+				return fmt.Errorf("migration %s failed: %v", name, err)
+			}
+
+			if _, err := tx.Exec(insertMigrationQuery, name); err != nil {
+				return err
+			}
+		}
+		return nil
+	})
+}

migrate_test.go

@@ -0,0 +1,44 @@
+package sqliteutil
+
+import (
+	"database/sql"
+	"embed"
+	"testing"
+)
+
+//go:embed test-migrations
+var testMigrationFS embed.FS
+
+func TestMigrate(t *testing.T) {
+	db, err := sql.Open("sqlite3", ":memory:")
+	if err != nil {
+		t.Fatal(err)
+	}
+
+	if err := Migrate(db, testMigrationFS); err != nil {
+		t.Fatal(err)
+	}
+
+	// Shouldn't have any effect.
+	if err := Migrate(db, testMigrationFS); err != nil {
+		t.Fatal(err)
+	}
+
+	query := `SELECT EXISTS(SELECT 1 FROM users WHERE UserID=$1)`
+	var exists bool
+
+	if err = db.QueryRow(query, 1).Scan(&exists); err != nil {
+		t.Fatal(err)
+	}
+	if exists {
+		t.Fatal("1 shouldn't exist")
+	}
+
+	if err = db.QueryRow(query, 2).Scan(&exists); err != nil {
+		t.Fatal(err)
+	}
+	if !exists {
+		t.Fatal("2 should exist")
+	}
+
+}

test-migrations/000.sql

@@ -0,0 +1,9 @@
+CREATE TABLE users(
+       UserID BIGINT NOT NULL PRIMARY KEY,
+       Email  TEXT   NOT NULL UNIQUE);
+
+CREATE TABLE user_notes(
+       UserID BIGINT NOT NULL REFERENCES users(UserID),
+       NoteID BIGINT NOT NULL,
+       Note   Text   NOT NULL,
+       PRIMARY KEY(UserID,NoteID));

test-migrations/001.sql

@@ -0,0 +1 @@
+INSERT INTO users(UserID, Email) VALUES (1, 'a@b.com'), (2, 'c@d.com');

test-migrations/002.sql

@@ -0,0 +1 @@
+DELETE FROM users WHERE UserID=1;

tx.go

@@ -0,0 +1,28 @@
+package sqliteutil
+
+import (
+	"database/sql"
+
+	_ "github.com/mattn/go-sqlite3"
+)
+
+// This is a convenience function to run a function within a transaction.
+func WithTx(db *sql.DB, fn func(*sql.Tx) error) error {
+	// Start a transaction.
+	tx, err := db.Begin()
+	if err != nil {
+		return err
+	}
+
+	err = fn(tx)
+
+	if err == nil {
+		err = tx.Commit()
+	}
+
+	if err != nil {
+		_ = tx.Rollback()
+	}
+
+	return err
+}