In-Memory Database with automatic versioning Backups. When starting the server the newest backup is loaded into memory.

csharp/App/Backend/Backend.csproj

@@ -27,6 +27,7 @@
         <PackageReference Include="Swashbuckle.AspNetCore" Version="6.2.3" />
         <PackageReference Include="Swashbuckle.AspNetCore.Filters" Version="7.0.6" />
         <PackageReference Include="Swashbuckle.AspNetCore.Filters.Abstractions" Version="7.0.6" />
+        <PackageReference Include="System.Data.SQLite.Core" Version="1.0.118" />
     </ItemGroup>
 
   

csharp/App/Backend/Controller.cs

@@ -20,7 +20,6 @@ public class Controller : ControllerBase
 
         if (user is null)
         {
-            Console.WriteLine("I have no user");
             throw new Exceptions(400,"Null User Exception", "Must provide a user to log in as.", Request.Path.Value!);
         }
 

csharp/App/Backend/Database/Create.cs

@@ -7,54 +7,61 @@ namespace InnovEnergy.App.Backend.Database;
 
 public static partial class Db 
 {
+    private static Boolean Insert(Object obj)
+    {
+        var success = Connection.Insert(obj) > 0;
+        if(success) BackupDatabase();
+        return success;
+    }
+    
     public static Boolean Create(Installation installation)
     {
         // SQLite wrapper is smart and *modifies* t's Id to the one generated (autoincrement) by the insertion
-        return Connection.Insert(installation) > 0;
+        return Insert(installation);
     }
     
     public static Boolean Create(DeletedInstallation installation)
     {
-        return Connection.Insert(installation) > 0;
+        return Insert(installation);
     }
     
     public static Boolean Create(Folder folder)
     {
-        return Connection.Insert(folder) > 0;
+        return Insert(folder);
     }
     
     public static Boolean Create(DeletedFolder folder)
     {
-        return Connection.Insert(folder) > 0;
+        return Insert(folder);
     }
     
     public static Boolean Create(User user)
     {
-        return Connection.Insert(user) > 0;
+        return Insert(user);
     }
     
     public static Boolean Create(DeletedUser user)
     {
-        return Connection.Insert(user) > 0;
+        return Insert(user);
     }
    
     public static Boolean Create(Session session)
     {
-        return Connection.Insert(session) > 0;
+        return Insert(session);
     }
     
     public static Boolean Create(InstallationAccess installationAccess)
     {
-        return Connection.Insert(installationAccess) > 0;
+        return Insert(installationAccess);
     }
     
     public static Boolean Create(FolderAccess folderAccess)
     {
-        return Connection.Insert(folderAccess) > 0;
+        return Insert(folderAccess);
     }
 
     public static Boolean Create(OrderNumber2Installation o2i)
     {
-        return Connection.Insert(o2i) > 0;
+        return Insert(o2i);
     }
 }

csharp/App/Backend/Database/Db.cs

@@ -1,12 +1,16 @@
+using System.Data.SQLite;
 using System.Reactive.Concurrency;
 using System.Reactive.Linq;
+using System.Runtime.InteropServices;
 using CliWrap;
 using CliWrap.Buffered;
 using InnovEnergy.App.Backend.DataTypes;
 using InnovEnergy.App.Backend.DataTypes.Methods;
 using InnovEnergy.App.Backend.Relations;
 using InnovEnergy.Lib.Utils;
+using Microsoft.Identity.Client;
 using SQLite;
+using SQLiteConnection = SQLite.SQLiteConnection;
 
 
 namespace InnovEnergy.App.Backend.Database;
@@ -16,8 +20,79 @@ public static partial class Db
 {
     internal const String DbPath = "./db.sqlite";
 
-    private static SQLiteConnection Connection { get; } = new SQLiteConnection(DbPath);
+    private static SQLiteConnection Connection { get; } = ((Func<SQLiteConnection>)(() =>
+    {
+        var latestDb = new DirectoryInfo(@"DbBackups").GetFiles()
+            .OrderBy(f => f.LastWriteTime)
+            .First().Name;
 
+        var fileConnection = new SQLiteConnection("DbBackups/"+latestDb);
+        
+        var memoryConnection = new SQLiteConnection(":memory:");
+        
+        // fileConnection.Backup(memoryConnection.DatabasePath);
+        
+        memoryConnection.CreateTable<User>();
+        memoryConnection.CreateTable<DeletedUser>();
+        memoryConnection.CreateTable<Installation>();
+        memoryConnection.CreateTable<DeletedInstallation>();
+        memoryConnection.CreateTable<DeletedFolder>();
+        memoryConnection.CreateTable<Folder>();
+        memoryConnection.CreateTable<FolderAccess>();
+        memoryConnection.CreateTable<InstallationAccess>();
+        memoryConnection.CreateTable<Session>();
+        memoryConnection.CreateTable<OrderNumber2Installation>();
+        
+        foreach (var obj in fileConnection.Table<Session>())
+        {
+            memoryConnection.Insert(obj);
+        }
+        foreach (var obj in fileConnection.Table<Folder>())
+        {
+            memoryConnection.Insert(obj);
+        }
+        foreach (var obj in fileConnection.Table<Installation>())
+        {
+            memoryConnection.Insert(obj);
+        }
+        foreach (var obj in fileConnection.Table<User>())
+        {
+            memoryConnection.Insert(obj);
+        }
+        foreach (var obj in fileConnection.Table<FolderAccess>())
+        {
+            memoryConnection.Insert(obj);
+        }
+        foreach (var obj in fileConnection.Table<InstallationAccess>())
+        {
+            memoryConnection.Insert(obj);
+        }
+        foreach (var obj in fileConnection.Table<OrderNumber2Installation>())
+        {
+            memoryConnection.Insert(obj);
+        }
+        foreach (var obj in fileConnection.Table<DeletedInstallation>())
+        {
+            memoryConnection.Insert(obj);
+        }
+        foreach (var obj in fileConnection.Table<DeletedUser>())
+        {
+            memoryConnection.Insert(obj);
+        }
+        foreach (var obj in fileConnection.Table<DeletedFolder>())
+        {
+            memoryConnection.Insert(obj);
+        }
+        
+        return memoryConnection;
+    }))();
+    
+    public static void BackupDatabase()
+    {
+        var filename = "db-" + DateTimeOffset.UtcNow.ToUnixTimeSeconds() + ".sqlite";
+        Connection.Backup("DbBackups/"+filename);
+    }
+    
     public static TableQuery<Session>                   Sessions                 => Connection.Table<Session>();
     public static TableQuery<Folder>                    Folders                  => Connection.Table<Folder>();
     public static TableQuery<Installation>              Installations            => Connection.Table<Installation>();

csharp/App/Backend/Database/Delete.cs

@@ -22,9 +22,10 @@ public static partial class Db
         Boolean DeleteDescendantFolderAndItsDependencies(Folder f)
         {
             FolderAccess  .Delete(r => r.FolderId == f.Id);
-            Installations.Delete(r => r.ParentId == f.Id); 
-            
-            return Folders.Delete(r => r.Id == f.Id) > 0;
+            Installations.Delete(r => r.ParentId == f.Id);
+            var delete = Folders.Delete(r => r.Id == f.Id);
+            BackupDatabase();
+            return delete > 0;
         }
     }
 
@@ -35,7 +36,9 @@ public static partial class Db
         Boolean DeleteInstallationAndItsDependencies()
         {
             InstallationAccess.Delete(i => i.InstallationId == installation.Id);
-            return Installations.Delete(i => i.Id == installation.Id) > 0;
+            var delete = Installations.Delete(i => i.Id == installation.Id);
+            BackupDatabase();
+            return delete > 0;
         }
     }
 
@@ -48,7 +51,9 @@ public static partial class Db
             FolderAccess      .Delete(u => u.UserId == user.Id);
             InstallationAccess.Delete(u => u.UserId == user.Id);
 
-            return Users.Delete(u => u.Id == user.Id) > 0;
+            var delete = Users.Delete(u => u.Id == user.Id);
+            BackupDatabase();
+            return delete > 0;
         }
     }
     
@@ -58,6 +63,8 @@ public static partial class Db
     // private!!
     private static Boolean Delete(Session session)
     {
-        return Sessions.Delete(s => s.Id == session.Id) > 0;
+        var delete = Sessions.Delete(s => s.Id == session.Id) > 0;
+        BackupDatabase();
+        return delete;
     }
 }

csharp/App/Backend/Database/Update.cs

@@ -5,14 +5,21 @@ namespace InnovEnergy.App.Backend.Database;
 
 public static partial class Db 
 {
+    private static Boolean Update(Object obj)
+    {
+        var success = Connection.Update(obj) > 0;
+        if(success) BackupDatabase();
+        return success;
+    }
+    
     public static Boolean Update(Folder folder)
     {
-        return Connection.Update(folder) > 0;
+        return Update(obj: folder);
     }
 
     public static Boolean Update(Installation installation)
     {
-        return Connection.Update(installation) > 0;
+        return Update(obj: installation);
     }
     
     public static Boolean Update(User user)
@@ -24,7 +31,7 @@ public static partial class Db
         user.ParentId = originalUser.ParentId;   
         user.Name = originalUser.Name;
             
-        return Connection.Update(user) > 0;
+        return Update(obj: user);
     }