begin implementing database. Down migrate doesnt work yet

src-tauri/Cargo.toml

@@ -23,3 +23,7 @@ tauri-plugin-opener = "2"
 serde = { version = "1", features = ["derive"] }
 serde_json = "1"
 
+# SQLx und Tokio für asynchrone DB-Zugriffe
+sqlx = { version = "0.7", features = ["runtime-tokio-rustls", "sqlite", "macros", "migrate"] }
+tokio = { version = "1", features = ["full"] }
+

src-tauri/migrations/0001_path_node_table.sql

@@ -0,0 +1,8 @@
+-- migrate:up
+CREATE TABLE PathNode (
+    id integer primary key,
+    title text,
+    description text
+)
+
+-- migrate:down

src-tauri/migrations/0002_node_exercise.sql

@@ -0,0 +1,8 @@
+-- migrate:up
+create table NodeExercise (
+    id integer primary key,
+    ex_type text,
+    content text
+)
+
+-- migrate:down

src-tauri/src/lib.rs

@@ -1,14 +1,50 @@
 // Learn more about Tauri commands at https://tauri.app/develop/calling-rust/
+use sqlx::sqlite::{self, SqlitePool};
+
 #[tauri::command]
 fn greet(name: &str) -> String {
     format!("Hello, {}! You've been greeted from Rust!", name)
 }
 
+// Beispiel: SQLite-Version abfragen
+#[tauri::command]
+async fn db_version(app_handle: tauri::AppHandle) -> Result<String, String> {
+    use tauri::Manager;
+    let base_dir = app_handle.path().app_data_dir().map_err(|e| format!("Konnte AppData-Verzeichnis nicht bestimmen: {}", e))?;
+
+    let db_path = base_dir.join("paths.sqlite");
+    println!("{:?}", db_path.to_str());
+
+    if let Some(parent) = db_path.parent() {
+        std::fs::create_dir_all(parent).map_err(|e| format!("Konnte Datenbankverzeichnis nicht erstellen: {}", e))?;
+    }
+
+    let db_opts = sqlite::SqliteConnectOptions::new()
+        .filename(&db_path)
+        .create_if_missing(true);
+
+    let pool = SqlitePool::connect_with(db_opts)
+        .await
+        .map_err(|e| e.to_string())?;
+
+    sqlx::migrate!("./migrations").run(&pool).await.map_err(|e| e.to_string())?;
+
+    let row: (String,) = sqlx::query_as("SELECT sqlite_version()")
+        .fetch_one(&pool)
+        .await
+        .map_err(|e| e.to_string())?;
+    Ok(row.0)
+}
+
 #[cfg_attr(mobile, tauri::mobile_entry_point)]
 pub fn run() {
     tauri::Builder::default()
         .plugin(tauri_plugin_opener::init())
-        .invoke_handler(tauri::generate_handler![greet])
+        .invoke_handler(tauri::generate_handler![greet, db_version])
         .run(tauri::generate_context!())
         .expect("error while running tauri application");
 }
+
+// Hinweis: Für produktive Nutzung sollte der Pool als State eingebunden werden,
+// damit er nicht bei jedem Aufruf neu erstellt wird. Siehe Tauri-Doku:
+// https://tauri.app/v1/guides/features/state/