Merge pull request #63 from atidev/app_http_context_more_safe_in_non_…

…http_context

Add nullable annotation for AppHttpContext.cs & it can work without http context

ATI.Services.Common/Variables/AppHttpContext.cs

@@ -1,99 +1,94 @@
+#nullable enable
 using System;
 using System.Collections.Generic;
 using System.Linq;
-using ATI.Services.Common.Extensions;
 using ATI.Services.Common.Metrics;
 using Microsoft.AspNetCore.Http;
+using Microsoft.Extensions.DependencyInjection;
 using Microsoft.Extensions.Primitives;
 
-namespace ATI.Services.Common.Variables
+namespace ATI.Services.Common.Variables;
+
+internal static class AppHttpContext
 {
-    internal static class AppHttpContext
-    {
-        private static IServiceProvider _services;
+    private static IServiceProvider? _services;
 
-        /// <summary>
-        /// Provides static access to the framework's services provider
-        /// </summary>
-        public static IServiceProvider Services
+    /// <summary>
+    /// Provides static access to the framework's services provider
+    /// </summary>
+    public static IServiceProvider? Services
+    {
+        get => _services;
+        set
         {
-            get => _services;
-            set
-            {
-                if (_services != null)
-                {
-                    return;
-                }
+            // If _services already initialized -> return
+            if (_services is not null)
+                return;
 
-                _services = value;
-            }
+            _services = value;
         }
+    }
 
-        public static string[] MetricsHeadersValues => GetHeadersValues(MetricsLabelsAndHeaders.UserHeaders);
-        public static Dictionary<string, string> HeadersAndValuesToProxy(List<string> headersToProxy) => GetHeadersAndValues(headersToProxy);
+    public static string[] MetricsHeadersValues => GetHeadersValues(MetricsLabelsAndHeaders.UserHeaders);
+    public static Dictionary<string, string> HeadersAndValuesToProxy(IReadOnlyCollection<string>? headersToProxy) => GetHeadersAndValues(headersToProxy);
 
-        /// <summary>
-        /// Provides static access to the current HttpContext
-        /// </summary>
-        private static HttpContext Current
+    /// <summary>
+    /// Provides static access to the current HttpContext
+    /// </summary>
+    private static HttpContext? Ctx
+    {
+        get
         {
-            get
-            {
-                var httpContextAccessor =
-                    _services.GetService(typeof(IHttpContextAccessor)) as IHttpContextAccessor;
-                return httpContextAccessor?.HttpContext;
-            }
+            ArgumentNullException.ThrowIfNull(Services, "IServiceProvider can't be null. Try do services.AddServiceVariables() in app configuration");
+
+            var httpContextAccessor = Services.GetService<IHttpContextAccessor>();
+            return httpContextAccessor?.HttpContext;
         }
+    }
 
-        private static string[] GetHeadersValues(string[] headersNames)
+    private static string[] GetHeadersValues(IReadOnlyCollection<string>? headersNames)
+    {
+        try
         {
-            if (headersNames == null || headersNames.Length == 0)
-                return headersNames;
+            if (headersNames is null || headersNames.Count == 0)
+                return Array.Empty<string>();
 
-            var context = Current;
-            var headersValues = headersNames.Select(label => GetHeaderValue(context, label)).ToArray();
+            var headersValues = headersNames.Select(label => GetHeaderValue(Ctx, label)).ToArray();
             return headersValues;
         }
-
-        private static string GetHeaderValue(HttpContext context, string headerName)
+        catch (ObjectDisposedException) // when thing happen outside http ctx e.g eventbus event handler
         {
-            if (context == null)
-            {
-                return "This service";
-            }
+            return Array.Empty<string>();
+        }
+    }
 
-            if (context.Request.Headers.TryGetValue(headerName, out var headerValues))
-            {
-                if (!headerValues[0].IsNullOrEmpty())
-                {
-                    return headerValues[0];
-                }
-            }
+    private static string GetHeaderValue(HttpContext? context, string headerName)
+    {
+        if (context is null)
+            return "This service";
 
-            return "Empty";
-        }
+        if (context.Request.Headers.TryGetValue(headerName, out var headerValues) && !StringValues.IsNullOrEmpty(headerValues))
+            return headerValues[0];
 
-        private static Dictionary<string, string> GetHeadersAndValues(IReadOnlyCollection<string> headersNames)
-        {
-            if (headersNames == null || headersNames.Count == 0)
-                return null;
+        return "Empty";
+    }
 
-            var context = Current;
-            if (context == null)
-                return null;
+    private static Dictionary<string, string> GetHeadersAndValues(IReadOnlyCollection<string>? headersNames)
+    {
+        if (headersNames is null || headersNames.Count == 0 || Ctx is null)
+            return new Dictionary<string, string>();
 
-            return headersNames
-                .Select(header => context.Request.Headers.TryGetValue(header, out var headerValues)
-                                  && !StringValues.IsNullOrEmpty(headerValues)
-                    ? new
-                    {
-                        Header = header,
-                        Value = headerValues[0]
-                    }
-                    : null)
-                .Where(headerAndValue => headerAndValue != null)
-                .ToDictionary(headerAndValue => headerAndValue.Header,
-                    headerAndValue => headerAndValue.Value);
-        }
+        return headersNames
+            .Select(header => Ctx.Request.Headers.TryGetValue(header, out var headerValues)
+                              && !StringValues.IsNullOrEmpty(headerValues)
+                ? new
+                {
+                    Header = header,
+                    Value = headerValues[0]
+                }
+                : null)
+            .Where(headerAndValue => headerAndValue != null)
+            .ToDictionary(headerAndValue => headerAndValue!.Header,
+                headerAndValue => headerAndValue!.Value);
     }
 }

ATI.Services.Common/Variables/ServiceVariablesExtensions.cs

@@ -12,8 +12,8 @@ public static void AddServiceVariables(this IServiceCollection services)
         {
             services.ConfigureByName<ServiceVariablesOptions>();
             services.AddTransient<ServiceVariablesInitializer>();
-            
-            services.AddSingleton<IHttpContextAccessor, HttpContextAccessor>();
+
+            services.AddHttpContextAccessor();
             AppHttpContext.Services = services.BuildServiceProvider(new ServiceProviderOptions().ValidateOnBuild);
         }
     }