Pg to bun (#148)

* start moving to bun

* changing more stuff

* more

* and yet more

* tests passing

* seems stable now

* more big changes

* small fix

* little fixes

internal/db/bundb/util.go

@@ -0,0 +1,78 @@
+/*
+   GoToSocial
+   Copyright (C) 2021 GoToSocial Authors admin@gotosocial.org
+
+   This program is free software: you can redistribute it and/or modify
+   it under the terms of the GNU Affero General Public License as published by
+   the Free Software Foundation, either version 3 of the License, or
+   (at your option) any later version.
+
+   This program is distributed in the hope that it will be useful,
+   but WITHOUT ANY WARRANTY; without even the implied warranty of
+   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+   GNU Affero General Public License for more details.
+
+   You should have received a copy of the GNU Affero General Public License
+   along with this program.  If not, see <http://www.gnu.org/licenses/>.
+*/
+
+package bundb
+
+import (
+	"context"
+	"strings"
+
+	"database/sql"
+
+	"github.com/superseriousbusiness/gotosocial/internal/db"
+	"github.com/uptrace/bun"
+)
+
+// processErrorResponse parses the given error and returns an appropriate DBError.
+func processErrorResponse(err error) db.Error {
+	switch err {
+	case nil:
+		return nil
+	case sql.ErrNoRows:
+		return db.ErrNoEntries
+	default:
+		if strings.Contains(err.Error(), "duplicate key value violates unique constraint") {
+			return db.ErrAlreadyExists
+		}
+		return err
+	}
+}
+
+func exists(ctx context.Context, q *bun.SelectQuery) (bool, db.Error) {
+	count, err := q.Count(ctx)
+
+	exists := count != 0
+
+	err = processErrorResponse(err)
+
+	if err != nil {
+		if err == db.ErrNoEntries {
+			return false, nil
+		}
+		return false, err
+	}
+
+	return exists, nil
+}
+
+func notExists(ctx context.Context, q *bun.SelectQuery) (bool, db.Error) {
+	count, err := q.Count(ctx)
+
+	notExists := count == 0
+
+	err = processErrorResponse(err)
+
+	if err != nil {
+		if err == db.ErrNoEntries {
+			return true, nil
+		}
+		return false, err
+	}
+
+	return notExists, nil
+}