Fix memory issue with WriteToStringAsync (graphql-dotnet#909)

* Fix memory issue with WriteToStringAsync
* Remove global.json with choco install in appveyor.yml
* Throw errors on invalid arguments

Author: joemcbride

appveyor.yml

@@ -1,10 +1,12 @@
-version: 2.3.0.{build}
+version: 2.4.0.{build}
 pull_requests:
   do_not_increment_build_number: true
 skip_tags: true
-skip_branch_with_pr: true
+skip_branch_with_pr: false
 test: off
 
+os: Visual Studio 2017
+
 environment:
   CI: true
 
@@ -15,6 +17,7 @@ nuget:
 
 install:
   - ps: Install-Product node LTS
+  - ps: choco install dotnetcore-sdk --no-progress --confirm --version 2.1.403
   - node --version
   - npm --version
   - dotnet --version
@@ -38,4 +41,3 @@ deploy:
     branch:
       - master
       - dev
-      - instance

global.json

@@ -1,6 +1,6 @@
 {
   "name": "graphql-dotnet",
-  "version": "2.3.0",
+  "version": "2.4.0",
   "description": "GraphQL for .NET",
   "main": "index.js",
   "scripts": {

package.json

@@ -2,7 +2,7 @@
 
   <PropertyGroup>
     <Description>GraphQL for .NET</Description>
-    <VersionPrefix>2.3.0</VersionPrefix>
+    <VersionPrefix>2.4.0</VersionPrefix>
     <Authors>Joe McBride</Authors>
     <TargetFrameworks>netstandard2.0;netstandard1.3;net45</TargetFrameworks>
     <AssemblyName>GraphQL</AssemblyName>

src/GraphQL/GraphQL.csproj

@@ -13,7 +13,7 @@ public interface IDocumentWriter
 
         Task<IByteResult> WriteAsync<T>(T value);
 
-        [Obsolete("This method is obsolete and will be removed in the next major version.  Use WriteAsync instead.")]
+        [Obsolete("This method is obsolete and will be removed in the next major version.  Use WriteAsync<T>(Stream, T) instead.")]
         string Write(object value);
     }
 
@@ -23,7 +23,7 @@ public class DocumentWriter : IDocumentWriter
         private readonly JsonArrayPool _jsonArrayPool = new JsonArrayPool(ArrayPool<char>.Shared);
         private readonly int _maxArrayLength = 1048576;
         private readonly JsonSerializer _serializer;
-        private static readonly Encoding Utf8Encoding = new UTF8Encoding(false);
+        internal static readonly Encoding Utf8Encoding = new UTF8Encoding(false);
 
         public DocumentWriter()
             : this(indent: false)
@@ -77,6 +77,13 @@ public async Task<IByteResult> WriteAsync<T>(T value)
 
         public string Write(object value)
         {
+            if (value == null) throw new ArgumentNullException(nameof(value));
+
+            if (!(value is ExecutionResult))
+            {
+                throw new ArgumentOutOfRangeException($"Expected {nameof(value)} to be a GraphQL.ExecutionResult, got {value.GetType().FullName}");
+            }
+
             return this.WriteToStringAsync((ExecutionResult) value).GetAwaiter().GetResult();
         }
     }
@@ -88,19 +95,19 @@ public static class DocumentWriterExtensions
         /// </summary>
         /// <param name="writer"></param>
         /// <param name="value"></param>
-        /// <param name="encoding"></param>
         /// <returns></returns>
-        public static async Task<string> WriteToStringAsync(this IDocumentWriter writer,
-            ExecutionResult value,
-            Encoding encoding = null)
+        public static async Task<string> WriteToStringAsync(
+            this IDocumentWriter writer,
+            ExecutionResult value)
         {
-            var resolvedEncoding = encoding ?? Encoding.UTF8;
-            using (var buffer = await writer.WriteAsync(value).ConfigureAwait(false))
+            using(var stream = new MemoryStream())
             {
-                return buffer.Result.Array != null
-                    ? resolvedEncoding.GetString(buffer.Result.Array, buffer.Result.Offset,
-                        buffer.Result.Count)
-                    : null;
+                await writer.WriteAsync(stream, value);
+                stream.Position = 0;
+                using (var reader = new StreamReader(stream, DocumentWriter.Utf8Encoding))
+                {
+                    return await reader.ReadToEndAsync();
+                }
             }
         }
     }

src/GraphQL/Http/DocumentWriter.cs

@@ -60,7 +60,7 @@ public HttpResponseStreamWriter(
             }
             if (!_stream.CanWrite)
             {
-                throw new ArgumentException("Stream is now writable", nameof(stream));
+                throw new ArgumentException("Stream is not writable", nameof(stream));
             }
 
             _charBufferSize = bufferSize;