Migrate to session storage

Author: andrewtelnov

DomainModels/DataStorage.cs

@@ -1,4 +1,5 @@
-using SurveyJSAsFormLibrary.Attributes;
+using Microsoft.AspNetCore.Http;
+using SurveyJSAsFormLibrary.Attributes;
 using System;
 using System.Collections.Generic;
 using System.ComponentModel.DataAnnotations;
@@ -9,18 +10,75 @@
 
 namespace SurveyJSAsFormLibrary.DomainModels
 {
+    public static class DatabaseEmulatorHttpContext
+    {
+        static IServiceProvider services = null;
+
+        public static IServiceProvider Services
+        {
+            get { return services; }
+            set
+            {
+                if (services != null)
+                {
+                    throw new Exception("Can't set once a value has already been set.");
+                }
+                services = value;
+            }
+        }
+        public static HttpContext Current
+        {
+            get
+            {
+                IHttpContextAccessor httpContextAccessor = services.GetService(typeof(IHttpContextAccessor)) as IHttpContextAccessor;
+                return httpContextAccessor?.HttpContext;
+            }
+        }
+
+    }
     public class DataStorage
     {
-        private static Dictionary<string, string> databaseEmulator = new Dictionary<string, string>();
+        const string idsName = "ids";
+        private static ISession currentSession {
+            get { return DatabaseEmulatorHttpContext.Current.Session; }
+        }
+        private static string GetDataFromDatabaseEmulator(string key)
+        {
+            return currentSession.GetString(key);
+        }
+        private static void SetDataFromDatabaseEmulator(string key, string data)
+        {
+            currentSession.SetString(key, data);
+            string ids = currentSession.GetString(idsName);
+            if (string.IsNullOrEmpty(ids)) ids = string.Empty;
+            key += ";";
+            if(!ids.Contains(key))
+            {
+                currentSession.SetString(idsName, ids + key);
+            }
+        }
+        public static IList<string> GetAllIdsByPrefixFromDatabaseEmulator(string keyPrefix)
+        {
+            var res = new List<string>();
+            string ids = currentSession.GetString(idsName);
+            if (string.IsNullOrEmpty(ids)) return res;
+            string[] allKeys = ids.Split(';');
+            foreach (string key in allKeys)
+            {
+                if (!string.IsNullOrEmpty(key) && key.StartsWith(keyPrefix))
+                {
+                    res.Add(GetDataFromDatabaseEmulator(key));
+                }
+            }
+            return res;
+        }
         public static string GetForm(Type type)
         {
-            string data;
-            DataStorage.databaseEmulator.TryGetValue(DataStorage.formId(type), out data);
-            return data;
+            return GetDataFromDatabaseEmulator(DataStorage.formId(type));
         }
         public static void SaveForm(Type type, string data)
         {
-            DataStorage.databaseEmulator[DataStorage.formId(type)] = data;
+            SetDataFromDatabaseEmulator(DataStorage.formId(type), data);
         }
         public static string GenerateId()
         {
@@ -31,8 +89,7 @@ public static string GenerateId()
         }
         public static string GetData(Type type, string id)
         {
-            string data;
-            DataStorage.databaseEmulator.TryGetValue(DataStorage.absoluteId(type, id), out data);
+            string data = GetDataFromDatabaseEmulator(DataStorage.absoluteId(type, id));
             if (string.IsNullOrEmpty(data))
             {
                 data = getJSONWithId(id);
@@ -42,19 +99,11 @@ public static string GetData(Type type, string id)
         public static void SaveData(Type type, string id, string data)
         {
             string key = DataStorage.absoluteId(type, id);
-            DataStorage.databaseEmulator[key] = data;
+            SetDataFromDatabaseEmulator(key, data);
         }
         public static IList<string> GetAllDataByType(Type type)
         {
-            var res = new List<string>();
-            foreach(KeyValuePair<string, string> item in databaseEmulator)
-            {
-                if(item.Key.StartsWith(type.Name + "-"))
-                {
-                    res.Add(item.Value);
-                }
-            }
-            return res;
+            return GetAllIdsByPrefixFromDatabaseEmulator(type.Name + "-");
         }
         private static string absoluteId(Type type, string id)
         {

Startup.cs

@@ -1,9 +1,11 @@
 using Microsoft.AspNetCore.Builder;
 using Microsoft.AspNetCore.Hosting;
+using Microsoft.AspNetCore.Http;
 using Microsoft.AspNetCore.HttpsPolicy;
 using Microsoft.Extensions.Configuration;
 using Microsoft.Extensions.DependencyInjection;
 using Microsoft.Extensions.Hosting;
+using SurveyJSAsFormLibrary.DomainModels;
 using System;
 using System.Collections.Generic;
 using System.Linq;
@@ -24,6 +26,9 @@ public Startup(IConfiguration configuration)
         public void ConfigureServices(IServiceCollection services)
         {
             services.AddControllersWithViews();
+            //We need these two lines to emulate database by storing data in user session
+            services.AddSession();
+            services.AddSingleton<IHttpContextAccessor, HttpContextAccessor>();
         }
 
         // This method gets called by the runtime. Use this method to configure the HTTP request pipeline.
@@ -41,8 +46,10 @@ public void Configure(IApplicationBuilder app, IWebHostEnvironment env)
             }
             app.UseHttpsRedirection();
             app.UseStaticFiles();
-
             app.UseRouting();
+            //We need these two lines to emulate database by storing data in user session
+            app.UseSession();
+            DatabaseEmulatorHttpContext.Services = app.ApplicationServices;
 
             app.UseAuthorization();