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rynowakrynowak
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Refactor content negotiation code into a service (#6998)
* Refactor content negotiation code into a service This is a refactor in anticipation of using this logic in some other places
1 parent 41efa40 commit 861d78f

21 files changed

+866
-799
lines changed

‎src/Microsoft.AspNetCore.Mvc.Core/DependencyInjection/MvcCoreServiceCollectionExtensions.cs

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@@ -250,6 +250,7 @@ internal static void AddMvcCoreServices(IServiceCollection services)
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services.TryAddSingleton<IHttpResponseStreamWriterFactory, MemoryPoolHttpResponseStreamWriterFactory>();
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services.TryAddSingleton(ArrayPool<byte>.Shared);
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services.TryAddSingleton(ArrayPool<char>.Shared);
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services.TryAddSingleton<OutputFormatterSelector, DefaultOutputFormatterSelector>();
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services.TryAddSingleton<IActionResultExecutor<ObjectResult>, ObjectResultExecutor>();
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services.TryAddSingleton<IActionResultExecutor<PhysicalFileResult>, PhysicalFileResultExecutor>();
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services.TryAddSingleton<IActionResultExecutor<VirtualFileResult>, VirtualFileResultExecutor>();

‎src/Microsoft.AspNetCore.Mvc.Core/Infrastructure/DefaultOutputFormatterSelector.cs

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// Copyright (c) .NET Foundation. All rights reserved.
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// Licensed under the Apache License, Version 2.0. See License.txt in the project root for license information.
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using System;
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using System.Collections.Generic;
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using System.Collections.ObjectModel;
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using Microsoft.AspNetCore.Http;
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using Microsoft.AspNetCore.Mvc.Core;
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using Microsoft.AspNetCore.Mvc.Formatters;
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using Microsoft.AspNetCore.Mvc.Formatters.Internal;
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using Microsoft.AspNetCore.Mvc.Internal;
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using Microsoft.Extensions.Logging;
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using Microsoft.Extensions.Options;
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using Microsoft.Extensions.Primitives;
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using Microsoft.Net.Http.Headers;
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namespace Microsoft.AspNetCore.Mvc.Infrastructure
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{
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public class DefaultOutputFormatterSelector : OutputFormatterSelector
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{
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private static readonly Comparison<MediaTypeSegmentWithQuality> _sortFunction = (left, right) =>
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{
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return left.Quality > right.Quality ? -1 : (left.Quality == right.Quality ? 0 : 1);
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};
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private readonly ILogger _logger;
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private readonly IList<IOutputFormatter> _formatters;
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private readonly bool _respectBrowserAcceptHeader;
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private readonly bool _returnHttpNotAcceptable;
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public DefaultOutputFormatterSelector(IOptions<MvcOptions> options, ILoggerFactory loggerFactory)
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{
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if (options == null)
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{
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throw new ArgumentNullException(nameof(options));
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}
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if (loggerFactory == null)
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{
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throw new ArgumentNullException(nameof(loggerFactory));
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}
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_logger = loggerFactory.CreateLogger<DefaultOutputFormatterSelector>();
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_formatters = new ReadOnlyCollection<IOutputFormatter>(options.Value.OutputFormatters);
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_respectBrowserAcceptHeader = options.Value.RespectBrowserAcceptHeader;
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_returnHttpNotAcceptable = options.Value.ReturnHttpNotAcceptable;
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}
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public override IOutputFormatter SelectFormatter(OutputFormatterCanWriteContext context, IList<IOutputFormatter> formatters, MediaTypeCollection contentTypes)
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{
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if (context == null)
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{
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throw new ArgumentNullException(nameof(context));
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}
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if (formatters == null)
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{
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throw new ArgumentNullException(nameof(formatters));
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}
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if (contentTypes == null)
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{
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throw new ArgumentNullException(nameof(contentTypes));
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}
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ValidateContentTypes(contentTypes);
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if (formatters.Count == 0)
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{
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formatters = _formatters;
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if (formatters.Count == 0)
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{
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throw new InvalidOperationException(Resources.FormatOutputFormattersAreRequired(
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typeof(MvcOptions).FullName,
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nameof(MvcOptions.OutputFormatters),
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typeof(IOutputFormatter).FullName));
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}
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}
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var request = context.HttpContext.Request;
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var acceptableMediaTypes = GetAcceptableMediaTypes(request);
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var selectFormatterWithoutRegardingAcceptHeader = false;
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IOutputFormatter selectedFormatter = null;
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if (acceptableMediaTypes.Count == 0)
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{
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// There is either no Accept header value, or it contained */* and we
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// are not currently respecting the 'browser accept header'.
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_logger.NoAcceptForNegotiation();
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selectFormatterWithoutRegardingAcceptHeader = true;
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}
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else
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{
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if (contentTypes.Count == 0)
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{
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// Use whatever formatter can meet the client's request
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selectedFormatter = SelectFormatterUsingSortedAcceptHeaders(
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context,
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formatters,
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acceptableMediaTypes);
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}
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else
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{
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// Verify that a content type from the context is compatible with the client's request
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selectedFormatter = SelectFormatterUsingSortedAcceptHeadersAndContentTypes(
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context,
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formatters,
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acceptableMediaTypes,
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contentTypes);
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}
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if (selectedFormatter == null && !_returnHttpNotAcceptable)
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{
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_logger.NoFormatterFromNegotiation(acceptableMediaTypes);
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selectFormatterWithoutRegardingAcceptHeader = true;
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}
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}
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if (selectFormatterWithoutRegardingAcceptHeader)
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{
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if (contentTypes.Count == 0)
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{
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selectedFormatter = SelectFormatterNotUsingContentType(
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context,
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formatters);
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}
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else
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{
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selectedFormatter = SelectFormatterUsingAnyAcceptableContentType(
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context,
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formatters,
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contentTypes);
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}
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}
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if (selectedFormatter == null)
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{
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// No formatter supports this.
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_logger.NoFormatter(context);
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return null;
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}
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_logger.FormatterSelected(selectedFormatter, context);
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return selectedFormatter;
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}
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private List<MediaTypeSegmentWithQuality> GetAcceptableMediaTypes(HttpRequest request)
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{
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var result = new List<MediaTypeSegmentWithQuality>();
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AcceptHeaderParser.ParseAcceptHeader(request.Headers[HeaderNames.Accept], result);
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for (var i = 0; i < result.Count; i++)
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{
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var mediaType = new MediaType(result[i].MediaType);
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if (!_respectBrowserAcceptHeader && mediaType.MatchesAllSubTypes && mediaType.MatchesAllTypes)
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{
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result.Clear();
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return result;
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}
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}
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result.Sort(_sortFunction);
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return result;
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}
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private IOutputFormatter SelectFormatterNotUsingContentType(
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OutputFormatterCanWriteContext formatterContext,
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IList<IOutputFormatter> formatters)
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{
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if (formatterContext == null)
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{
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throw new ArgumentNullException(nameof(formatterContext));
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}
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if (formatters == null)
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{
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throw new ArgumentNullException(nameof(formatters));
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}
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foreach (var formatter in formatters)
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{
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formatterContext.ContentType = new StringSegment();
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formatterContext.ContentTypeIsServerDefined = false;
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if (formatter.CanWriteResult(formatterContext))
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{
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return formatter;
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}
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}
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return null;
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}
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private IOutputFormatter SelectFormatterUsingSortedAcceptHeaders(
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OutputFormatterCanWriteContext formatterContext,
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IList<IOutputFormatter> formatters,
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IList<MediaTypeSegmentWithQuality> sortedAcceptHeaders)
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{
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if (formatterContext == null)
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{
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throw new ArgumentNullException(nameof(formatterContext));
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}
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if (formatters == null)
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{
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throw new ArgumentNullException(nameof(formatters));
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}
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if (sortedAcceptHeaders == null)
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{
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throw new ArgumentNullException(nameof(sortedAcceptHeaders));
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}
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for (var i = 0; i < sortedAcceptHeaders.Count; i++)
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{
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var mediaType = sortedAcceptHeaders[i];
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formatterContext.ContentType = mediaType.MediaType;
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formatterContext.ContentTypeIsServerDefined = false;
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for (var j = 0; j < formatters.Count; j++)
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{
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var formatter = formatters[j];
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if (formatter.CanWriteResult(formatterContext))
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{
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return formatter;
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}
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}
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}
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return null;
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}
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private IOutputFormatter SelectFormatterUsingAnyAcceptableContentType(
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OutputFormatterCanWriteContext formatterContext,
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IList<IOutputFormatter> formatters,
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MediaTypeCollection acceptableContentTypes)
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{
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if (formatterContext == null)
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{
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throw new ArgumentNullException(nameof(formatterContext));
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}
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if (formatters == null)
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{
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throw new ArgumentNullException(nameof(formatters));
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}
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if (acceptableContentTypes == null)
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{
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throw new ArgumentNullException(nameof(acceptableContentTypes));
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}
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foreach (var formatter in formatters)
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{
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foreach (var contentType in acceptableContentTypes)
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{
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formatterContext.ContentType = new StringSegment(contentType);
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formatterContext.ContentTypeIsServerDefined = true;
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if (formatter.CanWriteResult(formatterContext))
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{
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return formatter;
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}
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}
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}
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return null;
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}
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private IOutputFormatter SelectFormatterUsingSortedAcceptHeadersAndContentTypes(
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OutputFormatterCanWriteContext formatterContext,
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IList<IOutputFormatter> formatters,
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IList<MediaTypeSegmentWithQuality> sortedAcceptableContentTypes,
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MediaTypeCollection possibleOutputContentTypes)
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{
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for (var i = 0; i < sortedAcceptableContentTypes.Count; i++)
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{
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var acceptableContentType = new MediaType(sortedAcceptableContentTypes[i].MediaType);
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for (var j = 0; j < possibleOutputContentTypes.Count; j++)
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{
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var candidateContentType = new MediaType(possibleOutputContentTypes[j]);
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if (candidateContentType.IsSubsetOf(acceptableContentType))
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{
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for (var k = 0; k < formatters.Count; k++)
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{
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var formatter = formatters[k];
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formatterContext.ContentType = new StringSegment(possibleOutputContentTypes[j]);
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formatterContext.ContentTypeIsServerDefined = true;
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if (formatter.CanWriteResult(formatterContext))
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{
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return formatter;
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}
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}
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}
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}
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}
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return null;
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}
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private void ValidateContentTypes(MediaTypeCollection contentTypes)
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{
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for (var i = 0; i < contentTypes.Count; i++)
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{
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var contentType = contentTypes[i];
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var parsedContentType = new MediaType(contentType);
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if (parsedContentType.HasWildcard)
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{
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var message = Resources.FormatObjectResult_MatchAllContentType(
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contentType,
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nameof(ObjectResult.ContentTypes));
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throw new InvalidOperationException(message);
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}
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}
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}
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}
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}

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