fix Nullable Warnings

Author: nogic1008

src/MicroBatchFramework.WebHosting/BatchEngineHostingExtensions.cs

@@ -39,9 +39,10 @@ public static Task RunBatchEngineWebHosting(this IWebHostBuilder builder, string
                 {
                     if (swaggerOptions == null)
                     {
-                        var entryAsm = Assembly.GetEntryAssembly();
+                        // GetEntryAssembly() never returns null when called from managed code.
+                        var entryAsm = Assembly.GetEntryAssembly()!;
                         var xmlName = entryAsm.GetName().Name + ".xml";
-                        var xmlPath = Path.Combine(Path.GetDirectoryName(Assembly.GetEntryAssembly().Location), xmlName);
+                        var xmlPath = Path.Combine(Path.GetDirectoryName(entryAsm.Location) ?? "", xmlName);
                         swaggerOptions = new SwaggerOptions(entryAsm.GetName().Name, "", "/") { XmlDocumentPath = xmlPath };
                     }
                     services.AddSingleton<SwaggerOptions>(swaggerOptions);
@@ -101,7 +102,8 @@ static List<Type> CollectBatchTypes()
 
             foreach (var asm in AppDomain.CurrentDomain.GetAssemblies())
             {
-                if (asm.FullName.StartsWith("System") || asm.FullName.StartsWith("Microsoft.Extensions")) continue;
+                if (!(asm.FullName is null)
+                    && (asm.FullName.StartsWith("System") || asm.FullName.StartsWith("Microsoft.Extensions"))) continue;
 
                 Type[] types;
                 try
@@ -110,9 +112,11 @@ static List<Type> CollectBatchTypes()
                 }
                 catch (ReflectionTypeLoadException ex)
                 {
+                    // If Reflection cannot load a class, Types will be null.
                     types = ex.Types;
                 }
 
+                if (types is null) continue;
                 foreach (var item in types)
                 {
                     if (typeof(BatchBase).IsAssignableFrom(item) && item != typeof(BatchBase))

src/MicroBatchFramework.WebHosting/BatchEngineMiddleware.cs

@@ -123,7 +123,8 @@ public async Task Invoke(HttpContext httpContext)
                     args = new string[(httpContext.Request.Form.Count * 2) + 1];
                     {
                         var i = 0;
-                        args[i++] = methodInfo.DeclaringType.Name + "." + methodInfo.Name;
+                        // MemberInfo.DeclaringType is null only if it is a member of a VB Module.
+                        args[i++] = methodInfo.DeclaringType!.Name + "." + methodInfo.Name;
                         foreach (var item in httpContext.Request.Form)
                         {
                             args[i++] = "-" + item.Key;
@@ -135,7 +136,8 @@ public async Task Invoke(HttpContext httpContext)
                 }
                 else
                 {
-                    args = new[] { methodInfo.DeclaringType.Name + "." + methodInfo.Name };
+                    // MemberInfo.DeclaringType is null only if it is a member of a VB Module.
+                    args = new[] { methodInfo.DeclaringType!.Name + "." + methodInfo.Name };
                 }
             }
             catch (Exception ex)

src/MicroBatchFramework.WebHosting/Swagger/SwaggerDefinitionBuilder.cs

@@ -58,7 +58,8 @@ public byte[] BuildSwaggerJson()
                     : null;
 
                 doc.tags = handlers
-                    .Select(x => x.DeclaringType.Name)
+                    // MemberInfo.DeclaringType is null only if it is a member of a VB Module.
+                    .Select(x => x.DeclaringType!.Name)
                     .Distinct()
                     .Select(x =>
                     {
@@ -77,16 +78,19 @@ public byte[] BuildSwaggerJson()
 
                 foreach (var item in handlers)
                 {
+                    // MemberInfo.DeclaringType is null only if it is a member of a VB Module.
+                    string declaringTypeName = item.DeclaringType!.Name;
                     XmlCommentStructure xmlComment = null;
                     if (xDocLookup != null)
                     {
-                        xmlComment = xDocLookup[Tuple.Create(item.DeclaringType.Name, item.Name)].FirstOrDefault();
+                        // ParameterInfo.Name will be null only it is ReturnParameter.
+                        xmlComment = xDocLookup[Tuple.Create(declaringTypeName, item.Name!)].FirstOrDefault();
                     }
 
                     var parameters = BuildParameters(doc.definitions, xmlComment, item);
                     var operation = new Operation
                     {
-                        tags = new[] { item.DeclaringType.Name },
+                        tags = new[] { declaringTypeName },
                         summary = (xmlComment != null) ? xmlComment.Summary : "",
                         description = (xmlComment != null) ? xmlComment.Remarks : "",
                         parameters = parameters,
@@ -96,7 +100,7 @@ public byte[] BuildSwaggerJson()
                         }
                     };
 
-                    doc.paths.Add("/" + item.DeclaringType.Name + "/" + item.Name, new PathItem { post = operation }); // everything post.
+                    doc.paths.Add("/" + declaringTypeName + "/" + item.Name, new PathItem { post = operation }); // everything post.
                 }
 
                 using (var ms = new MemoryStream())
@@ -128,7 +132,7 @@ Schemas.Parameter[] BuildParameters(IDictionary<string, Schema> definitions, Xml
                     var parameterXmlComment = UnwrapTypeName(x.ParameterType);
                     if (xmlComment != null)
                     {
-                        xmlComment.Parameters.TryGetValue(x.Name, out parameterXmlComment);
+                        xmlComment.Parameters.TryGetValue(x.Name, out parameterXmlComment!);
                         parameterXmlComment = UnwrapTypeName(x.ParameterType) + " " + parameterXmlComment;
                     }
 
@@ -147,7 +151,8 @@ Schemas.Parameter[] BuildParameters(IDictionary<string, Schema> definitions, Xml
                     object[] enums = null;
                     if (x.ParameterType.GetTypeInfo().IsEnum || (collectionType != null && collectionType.GetTypeInfo().IsEnum))
                     {
-                        var enumType = (x.ParameterType.GetTypeInfo().IsEnum) ? x.ParameterType : collectionType;
+                        // Compiler cannot understand collectionType is not null.
+                        var enumType = (x.ParameterType.GetTypeInfo().IsEnum) ? x.ParameterType : collectionType!;
 
                         var enumValues = Enum.GetNames(enumType);
 
@@ -374,7 +379,8 @@ static string ToSwaggerDataType(Type type)
 
             if (type.IsNullable())
             {
-                type = Nullable.GetUnderlyingType(type);
+                // if type is Nullable<T>, it has UnderlyingType T.
+                type = Nullable.GetUnderlyingType(type)!;
             }
 
             if (type.GetTypeInfo().IsEnum || type == typeof(DateTime) || type == typeof(DateTimeOffset))
@@ -462,13 +468,13 @@ protected override JsonProperty CreateProperty(MemberInfo member, MemberSerializ
                             enumerable = instance
                                 .GetType()
                                 .GetProperty(member.Name)
-                                .GetValue(instance, null) as IEnumerable;
+                                ?.GetValue(instance, null) as IEnumerable;
                             break;
                         case MemberTypes.Field:
                             enumerable = instance
                                 .GetType()
                                 .GetField(member.Name)
-                                .GetValue(instance) as IEnumerable;
+                                ?.GetValue(instance) as IEnumerable;
                             break;
                         default:
                             break;