Simplify ManualImportModule null check

Signed-off-by: Robin Dadswell <robin@dadswell.email>

src/Readarr.Api.V1/ManualImport/ManualImportModule.cs

@@ -47,15 +47,11 @@ namespace Readarr.Api.V1.ManualImport
             var downloadId = (string)Request.Query.downloadId;
             NzbDrone.Core.Books.Author author = null;
 
-            var authorIdQuery = Request.Query.authorId;
-            if (authorIdQuery.HasValue)
-            {
-                var authorId = Convert.ToInt32(authorIdQuery.Value);
+            var authorIdQuery = Request.GetNullableIntegerQueryParameter("authorId", null);
 
-                if (authorId > 0)
-                {
-                    author = _authorService.GetAuthor(authorId);
-                }
+            if (authorIdQuery.HasValue && authorIdQuery.Value > 0)
+            {
+                author = _authorService.GetAuthor(Convert.ToInt32(authorIdQuery.Value));
             }
 
             var filter = Request.GetBooleanQueryParameter("filterExistingFiles", true) ? FilterFilesType.Matched : FilterFilesType.None;

src/Readarr.Http/Extensions/RequestExtensions.cs

@@ -66,5 +66,29 @@ namespace Readarr.Http.Extensions
 
             return defaultValue;
         }
+
+        public static Guid GetGuidQueryParameter(this Request request, string parameter, Guid defaultValue = default)
+        {
+            var parameterValue = request.Query[parameter];
+
+            if (parameterValue.HasValue)
+            {
+                return Guid.Parse(parameterValue.Value);
+            }
+
+            return defaultValue;
+        }
+
+        public static int? GetNullableIntegerQueryParameter(this Request request, string parameter, int? defaultValue = null)
+        {
+            var parameterValue = request.Query[parameter];
+
+            if (parameterValue.HasValue)
+            {
+                return int.Parse(parameterValue.Value);
+            }
+
+            return defaultValue;
+        }
     }
 }