[英]JsonMaxLength exception on deserializing large json objects
Intro: 介绍:
Web application, ASP.NET MVC 3, a controller action that accepts an instance of POCO model class with (potentially) large field. Web应用程序,ASP.NET MVC 3,一种控制器操作,它接受具有(可能)大字段的POCO模型类的实例。
Model class: 型号类:
public class View
{
[Required]
[RegularExpression(...)]
public object name { get; set; }
public object details { get; set; }
public object content { get; set; } // the problem field
}
Controller action: 控制器动作:
[ActionName(...)]
[Authorize(...)]
[HttpPost]
public ActionResult CreateView(View view)
{
if (!ModelState.IsValid) { return /*some ActionResult here*/;}
... //do other stuff, create object in db etc. return valid result
}
Problem: 问题:
An action should be able to accept large JSON objects (at least up to hundred megabytes in a single request and that's no joke). 一个动作应该能够接受大型JSON对象(在单个请求中至少高达100兆字节,这不是一个笑话)。 By default I met with several restrictions like
httpRuntime maxRequestLength
etc. - all solved except MaxJsonLengh - meaning that default ValueProviderFactory for JSON is not capable of handling such objects. 默认情况下,我遇到了一些限制,如
httpRuntime maxRequestLength
等。除了MaxJsonLengh之外,所有限制都解决了 - 这意味着JSON的默认ValueProviderFactory无法处理这些对象。
Tried: 尝试:
Setting 设置
<system.web.extensions>
<scripting>
<webServices>
<jsonSerialization maxJsonLength="2147483647"/>
</webServices>
</scripting>
</system.web.extensions>
Creating my own custom ValueProviderFactory as described in @Darin's answer here: 按照@ Darin的答案中的描述创建我自己的自定义ValueProviderFactory:
JsonValueProviderFactory throws "request too large" JsonValueProviderFactory抛出“请求太大”
Dictionary<String,Object>
here, but that's not what I want - I want to deserialize it to my lovely POCO objects and use them as input parameters for actions. Dictionary<String,Object>
,但这不是我想要的 - 我想将它反序列化为我可爱的POCO对象并将它们用作动作的输入参数。 So, the questions: 所以,问题:
Anyone can suggest a good solution? 有谁能建议一个好的解决方案?
The built-in JsonValueProviderFactory ignores the <jsonSerialization maxJsonLength="50000000"/>
setting. 内置的JsonValueProviderFactory忽略
<jsonSerialization maxJsonLength="50000000"/>
设置。 So you could write a custom factory by using the built-in implementation: 因此,您可以使用内置实现编写自定义工厂:
public sealed class MyJsonValueProviderFactory : ValueProviderFactory
{
private static void AddToBackingStore(Dictionary<string, object> backingStore, string prefix, object value)
{
IDictionary<string, object> d = value as IDictionary<string, object>;
if (d != null)
{
foreach (KeyValuePair<string, object> entry in d)
{
AddToBackingStore(backingStore, MakePropertyKey(prefix, entry.Key), entry.Value);
}
return;
}
IList l = value as IList;
if (l != null)
{
for (int i = 0; i < l.Count; i++)
{
AddToBackingStore(backingStore, MakeArrayKey(prefix, i), l[i]);
}
return;
}
// primitive
backingStore[prefix] = value;
}
private static object GetDeserializedObject(ControllerContext controllerContext)
{
if (!controllerContext.HttpContext.Request.ContentType.StartsWith("application/json", StringComparison.OrdinalIgnoreCase))
{
// not JSON request
return null;
}
StreamReader reader = new StreamReader(controllerContext.HttpContext.Request.InputStream);
string bodyText = reader.ReadToEnd();
if (String.IsNullOrEmpty(bodyText))
{
// no JSON data
return null;
}
JavaScriptSerializer serializer = new JavaScriptSerializer();
serializer.MaxJsonLength = 2147483647;
object jsonData = serializer.DeserializeObject(bodyText);
return jsonData;
}
public override IValueProvider GetValueProvider(ControllerContext controllerContext)
{
if (controllerContext == null)
{
throw new ArgumentNullException("controllerContext");
}
object jsonData = GetDeserializedObject(controllerContext);
if (jsonData == null)
{
return null;
}
Dictionary<string, object> backingStore = new Dictionary<string, object>(StringComparer.OrdinalIgnoreCase);
AddToBackingStore(backingStore, String.Empty, jsonData);
return new DictionaryValueProvider<object>(backingStore, CultureInfo.CurrentCulture);
}
private static string MakeArrayKey(string prefix, int index)
{
return prefix + "[" + index.ToString(CultureInfo.InvariantCulture) + "]";
}
private static string MakePropertyKey(string prefix, string propertyName)
{
return (String.IsNullOrEmpty(prefix)) ? propertyName : prefix + "." + propertyName;
}
}
The only modification I did compared to the default factory is adding the following line: 与默认工厂相比,我做的唯一修改是添加以下行:
serializer.MaxJsonLength = 2147483647;
Unfortunately this factory is not extensible at all, sealed stuff so I had to recreate it. 不幸的是,这个工厂根本不可扩展,密封的东西,所以我不得不重新创建它。
and in your Application_Start
: 并在您的
Application_Start
:
ValueProviderFactories.Factories.Remove(ValueProviderFactories.Factories.OfType<System.Web.Mvc.JsonValueProviderFactory>().FirstOrDefault());
ValueProviderFactories.Factories.Add(new MyJsonValueProviderFactory());
I found that the maxRequestLength did not solve the problem however. 我发现maxRequestLength并没有解决问题。 I resolved my issue with the below setting.
我用以下设置解决了我的问题。 It is cleaner than having to implement a custom ValueProviderFactory
它比必须实现自定义ValueProviderFactory更清晰
<appSettings>
<add key="aspnet:MaxJsonDeserializerMembers" value="150000" />
</appSettings>
Credit goes to the following questions: 信用可归结为以下问题:
JsonValueProviderFactory throws "request too large" JsonValueProviderFactory抛出“请求太大”
Getting "The JSON request was too large to be deserialized" 获取“JSON请求太大而无法反序列化”
This setting obviously relates to a highly complex json model and not the actual size. 此设置显然与高度复杂的json模型有关,而与实际大小无关。
The solution of Darin Dimitrov works for me but i need reset the position of the stream of the request before read it, adding this line: Darin Dimitrov的解决方案对我有用,但我需要在读取之前重置请求流的位置,添加以下行:
controllerContext.HttpContext.Request.InputStream.Position = 0;
So now, the method GetDeserializedObject looks like this: 所以现在,方法GetDeserializedObject如下所示:
private static object GetDeserializedObject(ControllerContext controllerContext)
{
if (!controllerContext.HttpContext.Request.ContentType.StartsWith("application/json", StringComparison.OrdinalIgnoreCase))
{
// not JSON request
return null;
}
controllerContext.HttpContext.Request.InputStream.Position = 0;
StreamReader reader = new StreamReader(controllerContext.HttpContext.Request.InputStream);
string bodyText = reader.ReadToEnd();
if (String.IsNullOrEmpty(bodyText))
{
// no JSON data
return null;
}
JavaScriptSerializer serializer = new JavaScriptSerializer();
serializer.MaxJsonLength = 2147483647;
object jsonData = serializer.DeserializeObject(bodyText);
return jsonData;
}
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