fix:#34 added transaction for main fetch datasource

backend/service/fetch/v2/fetcher.go

@@ -17,9 +17,12 @@
 package v2
 
 import (
+	"database/sql"
 	"fmt"
 	"github.com/google/uuid"
+	"github.com/pocketbase/dbx"
 	"github.com/pocketbase/pocketbase"
+	"github.com/pocketbase/pocketbase/daos"
 	"golang.org/x/net/html"
 	"htwkalender/model"
 	"htwkalender/service/db"
@@ -89,21 +92,50 @@ func fetchAndSaveAllEventsForSemester(
 	var savedRecords []model.Event
 	url := stubUrl[0] + semester + stubUrl[1]
 	events, err := parseEventForOneSemester(url)
+
 	if err != nil {
 		return nil, fmt.Errorf("failed to parse events for "+semester+": %w", err)
 	}
-	err = db.DeleteAllEventsBySemesterWithoutCourse(app, "Sport", semester)
-	if err != nil {
-		return nil, fmt.Errorf("failed to delete all events for "+semester+": %w", err)
-	}
-	savedEvents, dbError := db.SaveEvents(events, app)
-	if dbError != nil {
-		return nil, fmt.Errorf("failed to save events for "+semester+": %w", dbError)
-	}
-	savedRecords = append(savedRecords, savedEvents...)
+
+	err = updateDatabase(app, events, "Sport", semester)
+
 	return savedRecords, err
 }
 
+func updateDatabase(app *pocketbase.PocketBase, eventsToBeAdded []model.Event, course string, semester string) error {
+
+	var addedEvents []model.Event
+	var err error
+
+	// to in transaction the events will be added and deleted
+	err = app.Dao().RunInTransaction(func(txDao *daos.Dao) error {
+		var execute sql.Result
+		execute, err = txDao.DB().Delete("events",
+			dbx.NewExp("course != {:course} AND semester = {:semester}",
+				dbx.Params{"course": course, "semester": semester})).Execute()
+		if err != nil {
+			return err
+		}
+		var rows int64
+		rows, err = execute.RowsAffected()
+		slog.Info("Deleted events: ", "events", rows)
+
+		addedEvents, err = db.SaveEventsTxDao(eventsToBeAdded, txDao)
+		if err != nil {
+			return err
+		}
+
+		return nil
+	})
+	if err != nil {
+		return err
+	}
+
+	slog.Info("Added events: ", "events", len(addedEvents))
+
+	return nil
+}
+
 func parseEventForOneSemester(url string) ([]model.Event, error) {
 	// Fetch Webpage from URL
 	webpage, err := fetch.GetHTML(url)