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// Copyright (c) Microsoft Corporation. All rights reserved. See License.txt in the project root for license information.
using System.Collections.Generic;
using System.ComponentModel;
using System.Net.Http.Formatting;
using System.Net.Http.Headers;
using System.Threading.Tasks;
namespace System.Net.Http
{
/// <summary>
/// Extension methods to allow strongly typed objects to be read from <see cref="HttpContent"/> instances.
/// </summary>
[EditorBrowsable(EditorBrowsableState.Never)]
public static class HttpContentExtensions
{
/// <summary>
/// Returns a <see cref="Task"/> that will yield an object of the specified <paramref name="type"/>
/// from the <paramref name="content"/> instance.
/// </summary>
/// <remarks>This override use the built-in collection of formatters.</remarks>
/// <param name="content">The <see cref="HttpContent"/> instance from which to read.</param>
/// <param name="type">The type of the object to read.</param>
/// <returns>A <see cref="Task"/> that will yield an object instance of the specified type.</returns>
public static Task<object> ReadAsAsync(this HttpContent content, Type type)
{
return content.ReadAsAsync(type, new MediaTypeFormatterCollection());
}
/// <summary>
/// Returns a <see cref="Task"/> that will yield an object of the specified <paramref name="type"/>
/// from the <paramref name="content"/> instance using one of the provided <paramref name="formatters"/>
/// to deserialize the content.
/// </summary>
/// <param name="content">The <see cref="HttpContent"/> instance from which to read.</param>
/// <param name="type">The type of the object to read.</param>
/// <param name="formatters">The collection of <see cref="MediaTypeFormatter"/> instances to use.</param>
/// <returns>An object instance of the specified type.</returns>
public static Task<object> ReadAsAsync(this HttpContent content, Type type, IEnumerable<MediaTypeFormatter> formatters)
{
return ReadAsAsync<object>(content, type, formatters, null);
}
/// <summary>
/// Returns a <see cref="Task"/> that will yield an object of the specified <paramref name="type"/>
/// from the <paramref name="content"/> instance using one of the provided <paramref name="formatters"/>
/// to deserialize the content.
/// </summary>
/// <param name="content">The <see cref="HttpContent"/> instance from which to read.</param>
/// <param name="type">The type of the object to read.</param>
/// <param name="formatters">The collection of <see cref="MediaTypeFormatter"/> instances to use.</param>
/// <param name="formatterLogger">The <see cref="IFormatterLogger"/> to log events to.</param>
/// <returns>An object instance of the specified type.</returns>
public static Task<object> ReadAsAsync(this HttpContent content, Type type, IEnumerable<MediaTypeFormatter> formatters, IFormatterLogger formatterLogger)
{
return ReadAsAsync<object>(content, type, formatters, formatterLogger);
}
/// <summary>
/// Returns a <see cref="Task"/> that will yield an object of the specified
/// type <typeparamref name="T"/> from the <paramref name="content"/> instance.
/// </summary>
/// <remarks>This override use the built-in collection of formatters.</remarks>
/// <typeparam name="T">The type of the object to read.</typeparam>
/// <param name="content">The <see cref="HttpContent"/> instance from which to read.</param>
/// <returns>An object instance of the specified type.</returns>
public static Task<T> ReadAsAsync<T>(this HttpContent content)
{
return content.ReadAsAsync<T>(new MediaTypeFormatterCollection());
}
/// <summary>
/// Returns a <see cref="Task"/> that will yield an object of the specified
/// type <typeparamref name="T"/> from the <paramref name="content"/> instance.
/// </summary>
/// <typeparam name="T">The type of the object to read.</typeparam>
/// <param name="content">The <see cref="HttpContent"/> instance from which to read.</param>
/// <param name="formatters">The collection of <see cref="MediaTypeFormatter"/> instances to use.</param>
/// <returns>An object instance of the specified type.</returns>
public static Task<T> ReadAsAsync<T>(this HttpContent content, IEnumerable<MediaTypeFormatter> formatters)
{
return ReadAsAsync<T>(content, typeof(T), formatters, null);
}
/// <summary>
/// Returns a <see cref="Task"/> that will yield an object of the specified
/// type <typeparamref name="T"/> from the <paramref name="content"/> instance.
/// </summary>
/// <typeparam name="T">The type of the object to read.</typeparam>
/// <param name="content">The <see cref="HttpContent"/> instance from which to read.</param>
/// <param name="formatters">The collection of <see cref="MediaTypeFormatter"/> instances to use.</param>
/// <param name="formatterLogger">The <see cref="IFormatterLogger"/> to log events to.</param>
/// <returns>An object instance of the specified type.</returns>
public static Task<T> ReadAsAsync<T>(this HttpContent content, IEnumerable<MediaTypeFormatter> formatters, IFormatterLogger formatterLogger)
{
return ReadAsAsync<T>(content, typeof(T), formatters, formatterLogger);
}
// There are many helper overloads for ReadAs*(). Provide one worker function to ensure the logic is shared.
//
// For loosely typed, T = Object, type = specific class.
// For strongly typed, T == type.GetType()
private static Task<T> ReadAsAsync<T>(HttpContent content, Type type, IEnumerable<MediaTypeFormatter> formatters, IFormatterLogger formatterLogger)
{
if (content == null)
{
throw new ArgumentNullException("content");
}
if (type == null)
{
throw new ArgumentNullException("type");
}
if (formatters == null)
{
throw new ArgumentNullException("formatters");
}
ObjectContent objectContent = content as ObjectContent;
if (objectContent != null && objectContent.Value != null && type.IsAssignableFrom(objectContent.Value.GetType()))
{
return TaskHelpers.FromResult((T)objectContent.Value);
}
MediaTypeFormatter formatter = null;
MediaTypeHeaderValue mediaType = content.Headers.ContentType;
if (mediaType != null)
{
formatter = new MediaTypeFormatterCollection(formatters).FindReader(type, mediaType);
}
if (formatter == null)
{
string mediaTypeAsString = mediaType != null ? mediaType.MediaType : Properties.Resources.UndefinedMediaType;
throw new InvalidOperationException(
RS.Format(Properties.Resources.NoReadSerializerAvailable, type.Name, mediaTypeAsString));
}
return content.ReadAsStreamAsync()
.Then(stream => formatter.ReadFromStreamAsync(type, stream, content.Headers, formatterLogger)
.Then(value => (T)value));
}
}
}
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