我可以在web.config中为maxJsonLength设置无限长度吗？

Question

我正在使用jQuery的自动完成功能.当我尝试检索超过17000条记录的列表(每条记录的长度不超过10条)时,它超出了长度并抛出错误:

异常信息:
异常类型:InvalidOperationException
异常消息:使用JSON JavaScriptSerializer进行序列化或反序列化时出错.字符串的长度超过maxJsonLength属性上设置的值.

我可以设置无限长度maxJsonLength的web.config？如果没有,我可以设置的最大长度是多少？

Answer 1

注意:此答案仅适用于Web服务,如果您从Controller方法返回JSON,请确保您也阅读以下SO答案:https://stackoverflow.com/a/7207539/1246870

所述MaxJsonLength属性不能是无限的,是整数属性默认为102400(10万).

您可以在web.config上设置MaxJsonLength属性:

<configuration> 
   <system.web.extensions>
       <scripting>
           <webServices>
               <jsonSerialization maxJsonLength="50000000"/>
           </webServices>
       </scripting>
   </system.web.extensions>
</configuration> 

Answer 2

如果您使用的是MVC 4,请务必查看此答案.

如果您仍然收到错误:

• 将maxJsonLength属性设置为web.config中的最大值后
• 并且您知道您的数据长度小于此值
• 并且您没有使用Web服务方法进行JavaScript序列化

你的问题很可能是:

MaxJsonLength属性的值仅适用于异步通信层用于调用Web服务方法的内部JavaScriptSerializer实例.(MSDN:ScriptingJsonSerializationSection.MaxJsonLength属性)

基本上,"内部" JavaScriptSerializer尊重maxJsonLength从Web方法调用时的值; 直接使用的一个JavaScriptSerializer(或经由MVC行动的方法/控制器使用)不不尊重maxJsonLength属性,至少没有从systemWebExtensions.scripting.webServices.jsonSerializationweb.config中的部分.

作为解决方法,您可以在Controller中(或任何地方)执行以下操作:

var serializer = new JavaScriptSerializer();

// For simplicity just use Int32's max value.
// You could always read the value from the config section mentioned above.
serializer.MaxJsonLength = Int32.MaxValue;

var resultData = new { Value = "foo", Text = "var" };
var result = new ContentResult{
    Content = serializer.Serialize(resultData),
    ContentType = "application/json"
};
return result;

这个答案是我对这个asp.net论坛答案的解释.

Answer 3

在MVC 4中,您可以:

protected override JsonResult Json(object data, string contentType, System.Text.Encoding contentEncoding, JsonRequestBehavior behavior)
{
    return new JsonResult()
    {
        Data = data,
        ContentType = contentType,
        ContentEncoding = contentEncoding,
        JsonRequestBehavior = behavior,
        MaxJsonLength = Int32.MaxValue
    };
}

在你的控制器中.

加成:

对于任何困惑您需要指定的参数的人来说,调用可能如下所示:

Json(
    new {
        field1 = true,
        field2 = "value"
        },
    "application/json",
    Encoding.UTF8,
    JsonRequestBehavior.AllowGet
);

Answer 4

您可以在web.config文件中配置json请求的最大长度:

<configuration>
    <system.web.extensions>
        <scripting>
            <webServices>
                <jsonSerialization maxJsonLength="....">
                </jsonSerialization>
            </webServices>
        </scripting>
    </system.web.extensions>
</configuration>

maxJsonLength的默认值是102400.有关更多详细信息,请参阅此MSDN页面:http://msdn.microsoft.com/en-us/library/bb763183.aspx

Answer 5

我在ASP.NET Web窗体中遇到了这个问题.它完全忽略了web.config文件设置所以我这样做了:

        JavaScriptSerializer serializer = new JavaScriptSerializer();

        serializer.MaxJsonLength = Int32.MaxValue; 

        return serializer.Serialize(response);

当然总的来说这是一种可怕的做法.如果要在Web服务调用中发送这么多数据,您应该看一下不同的方法.

Answer 6

如果在web.config设置之后仍然出现错误,如下所示:

<configuration> 
   <system.web.extensions>
       <scripting>
           <webServices>
               <jsonSerialization maxJsonLength="50000000"/>
           </webServices>
       </scripting>
   </system.web.extensions>
</configuration> 

我解决了以下问题:

   public ActionResult/JsonResult getData()
   {
      var jsonResult = Json(superlargedata, JsonRequestBehavior.AllowGet);
      jsonResult.MaxJsonLength = int.MaxValue;
      return jsonResult;
    }

我希望这应该有所帮助.

Answer 7

我修好了它.

//your Json data here
string json_object="........";
JavaScriptSerializer jsJson = new JavaScriptSerializer();
jsJson.MaxJsonLength = 2147483644;
MyClass obj = jsJson.Deserialize<MyClass>(json_object);

它工作得很好.

Answer 8

我遵循了vestigal的回答并得到了这个解决方案:

当我需要将一个大的json发布到控制器中的一个动作时,我会在使用JSON JavaScriptSerializer进行反序列化时得到着名的"错误."字符串的长度超过了maxJsonLength属性上设置的值.\ r \nParameter name:input价值提供者".

我做的是创建一个新的ValueProviderFactory,LargeJsonValueProviderFactory,并在GetDeserializedObject方法中设置MaxJsonLength = Int32.MaxValue

public sealed class LargeJsonValueProviderFactory : ValueProviderFactory
{
private static void AddToBackingStore(LargeJsonValueProviderFactory.EntryLimitedDictionary backingStore, string prefix, object value)
{
    IDictionary<string, object> dictionary = value as IDictionary<string, object>;
    if (dictionary != null)
    {
        foreach (KeyValuePair<string, object> keyValuePair in (IEnumerable<KeyValuePair<string, object>>) dictionary)
            LargeJsonValueProviderFactory.AddToBackingStore(backingStore, LargeJsonValueProviderFactory.MakePropertyKey(prefix, keyValuePair.Key), keyValuePair.Value);
    }
    else
    {
        IList list = value as IList;
        if (list != null)
        {
            for (int index = 0; index < list.Count; ++index)
                LargeJsonValueProviderFactory.AddToBackingStore(backingStore, LargeJsonValueProviderFactory.MakeArrayKey(prefix, index), list[index]);
        }
        else
            backingStore.Add(prefix, value);
    }
}

private static object GetDeserializedObject(ControllerContext controllerContext)
{
    if (!controllerContext.HttpContext.Request.ContentType.StartsWith("application/json", StringComparison.OrdinalIgnoreCase))
        return (object) null;
    string end = new StreamReader(controllerContext.HttpContext.Request.InputStream).ReadToEnd();
    if (string.IsNullOrEmpty(end))
        return (object) null;

    var serializer = new JavaScriptSerializer {MaxJsonLength = Int32.MaxValue};

    return serializer.DeserializeObject(end);
}

/// <summary>Returns a JSON value-provider object for the specified controller context.</summary>
/// <returns>A JSON value-provider object for the specified controller context.</returns>
/// <param name="controllerContext">The controller context.</param>
public override IValueProvider GetValueProvider(ControllerContext controllerContext)
{
    if (controllerContext == null)
        throw new ArgumentNullException("controllerContext");
    object deserializedObject = LargeJsonValueProviderFactory.GetDeserializedObject(controllerContext);
    if (deserializedObject == null)
        return (IValueProvider) null;
    Dictionary<string, object> dictionary = new Dictionary<string, object>((IEqualityComparer<string>) StringComparer.OrdinalIgnoreCase);
    LargeJsonValueProviderFactory.AddToBackingStore(new LargeJsonValueProviderFactory.EntryLimitedDictionary((IDictionary<string, object>) dictionary), string.Empty, deserializedObject);
    return (IValueProvider) new DictionaryValueProvider<object>((IDictionary<string, object>) dictionary, CultureInfo.CurrentCulture);
}

private static string MakeArrayKey(string prefix, int index)
{
    return prefix + "[" + index.ToString((IFormatProvider) CultureInfo.InvariantCulture) + "]";
}

private static string MakePropertyKey(string prefix, string propertyName)
{
    if (!string.IsNullOrEmpty(prefix))
        return prefix + "." + propertyName;
    return propertyName;
}

private class EntryLimitedDictionary
{
    private static int _maximumDepth = LargeJsonValueProviderFactory.EntryLimitedDictionary.GetMaximumDepth();
    private readonly IDictionary<string, object> _innerDictionary;
    private int _itemCount;

    public EntryLimitedDictionary(IDictionary<string, object> innerDictionary)
    {
        this._innerDictionary = innerDictionary;
    }

    public void Add(string key, object value)
    {
        if (++this._itemCount > LargeJsonValueProviderFactory.EntryLimitedDictionary._maximumDepth)
            throw new InvalidOperationException("JsonValueProviderFactory_RequestTooLarge");
        this._innerDictionary.Add(key, value);
    }

    private static int GetMaximumDepth()
    {
        NameValueCollection appSettings = ConfigurationManager.AppSettings;
        if (appSettings != null)
        {
            string[] values = appSettings.GetValues("aspnet:MaxJsonDeserializerMembers");
            int result;
            if (values != null && values.Length > 0 && int.TryParse(values[0], out result))
                return result;
        }
        return 1000;
    }
}

}

然后,在Global.asax.cs的Application_Start方法中,将ValueProviderFactory替换为新的:

protected void Application_Start()
{
    ...

    //Add LargeJsonValueProviderFactory
    ValueProviderFactory jsonFactory = null;
    foreach (var factory in ValueProviderFactories.Factories)
    {
        if (factory.GetType().FullName == "System.Web.Mvc.JsonValueProviderFactory")
        {
            jsonFactory = factory;
            break;
        }
    }

    if (jsonFactory != null)
    {
        ValueProviderFactories.Factories.Remove(jsonFactory);
    }

    var largeJsonValueProviderFactory = new LargeJsonValueProviderFactory();
    ValueProviderFactories.Factories.Add(largeJsonValueProviderFactory);
}

Answer 9

如果在您的web.config中实现上述添加后,您会收到"无法识别的配置部分system.web.extensions."错误,然后尝试将此添加到您的web.config中<ConfigSections>:

            <sectionGroup name="system.web.extensions" type="System.Web.Extensions">
              <sectionGroup name="scripting" type="System.Web.Extensions">
                    <sectionGroup name="webServices" type="System.Web.Extensions">
                          <section name="jsonSerialization" type="System.Web.Extensions"/>
                    </sectionGroup>
              </sectionGroup>
        </sectionGroup>

Answer 10

你可以把这一行写入Controller

json.MaxJsonLength = 2147483644;

你也可以把这一行写进去 web.config

<configuration>
  <system.web.extensions>
    <scripting>
        <webServices>
            <jsonSerialization maxJsonLength="2147483647">
            </jsonSerialization>
        </webServices>
    </scripting>
  </system.web.extensions>

`

为了安全起见,请同时使用两者.

Answer 11

如果从MVC中的MiniProfiler收到此错误,则可以通过将属性设置MiniProfiler.Settings.MaxJsonResponseSize为所需的值来增加该值.默认情况下,此工具似乎忽略config中设置的值.

MiniProfiler.Settings.MaxJsonResponseSize = 104857600;

礼貌mvc-mini-profiler.

Answer 12

只需在MVC的Action方法中设置MaxJsonLength proprty即可

JsonResult json= Json(classObject, JsonRequestBehavior.AllowGet);
json.MaxJsonLength = int.MaxValue;
return json;

Answer 13

我建议将其设置为Int32.MaxValue.

JavaScriptSerializer serializer = new JavaScriptSerializer();
serializer.MaxJsonLength = Int32.MaxValue;

Answer 14

一些属性魔法怎么样？

[AttributeUsage(AttributeTargets.Class | AttributeTargets.Method, Inherited = true, AllowMultiple = false)]
public class MaxJsonSizeAttribute : ActionFilterAttribute
{
    // Default: 10 MB worth of one byte chars
    private int maxLength = 10 * 1024 * 1024;

    public int MaxLength
    {
        set
        {
            if (value < 0) throw new ArgumentOutOfRangeException("value", "Value must be at least 0.");

            maxLength = value;
        }
        get { return maxLength; }
    }

    public override void OnActionExecuted(ActionExecutedContext filterContext)
    {
        JsonResult json = filterContext.Result as JsonResult;
        if (json != null)
        {
            if (maxLength == 0)
            {
                json.MaxJsonLength = int.MaxValue;
            }
            else
            {
                json.MaxJsonLength = maxLength;
            }
        }
    }
}

然后,您可以使用全局筛选器配置或控制器/操作方式全局应用它.

Answer 15

问题实际上是您是否真的需要返回17,000条记录？您打算如何处理浏览器中的所有数据？无论如何，用户不会滚动浏览17000行。

更好的方法是仅检索“前几个”记录，并根据需要加载更多记录。

Answer 16

如果您在查看时遇到此类问题，可以使用以下方法来解决。这里我使用了Newtonsoft包。

@using Newtonsoft.Json
<script type="text/javascript">
    var partData = @Html.Raw(JsonConvert.SerializeObject(ViewBag.Part));
</script>

Answer 17

替代 ASP.NET MVC 5 修复：

（我的与上面的 MFC 答案类似，有一些小变化）

我还没有准备好更改为 Json.NET，就我而言，错误是在请求期间发生的。在我的场景中，最好的方法是修改实际的JsonValueProviderFactory，将修复应用到全局项目，并且可以通过编辑文件global.cs来完成。

JsonValueProviderConfig.Config(ValueProviderFactories.Factories);

添加 web.config 条目：

<add key="aspnet:MaxJsonLength" value="20971520" />

然后创建以下两个类

public class JsonValueProviderConfig
{
    public static void Config(ValueProviderFactoryCollection factories)
    {
        var jsonProviderFactory = factories.OfType<JsonValueProviderFactory>().Single();
        factories.Remove(jsonProviderFactory);
        factories.Add(new CustomJsonValueProviderFactory());
    }
}

这基本上是默认实现的精确副本，System.Web.Mvc但添加了可配置的 web.config appsetting 值aspnet:MaxJsonLength。

public class CustomJsonValueProviderFactory : ValueProviderFactory
{

    /// <summary>Returns a JSON value-provider object for the specified controller context.</summary>
    /// <returns>A JSON value-provider object for the specified controller context.</returns>
    /// <param name="controllerContext">The controller context.</param>
    public override IValueProvider GetValueProvider(ControllerContext controllerContext)
    {
        if (controllerContext == null)
            throw new ArgumentNullException("controllerContext");

        object deserializedObject = CustomJsonValueProviderFactory.GetDeserializedObject(controllerContext);
        if (deserializedObject == null)
            return null;

        Dictionary<string, object> strs = new Dictionary<string, object>(StringComparer.OrdinalIgnoreCase);
        CustomJsonValueProviderFactory.AddToBackingStore(new CustomJsonValueProviderFactory.EntryLimitedDictionary(strs), string.Empty, deserializedObject);

        return new DictionaryValueProvider<object>(strs, CultureInfo.CurrentCulture);
    }

    private static object GetDeserializedObject(ControllerContext controllerContext)
    {
        if (!controllerContext.HttpContext.Request.ContentType.StartsWith("application/json", StringComparison.OrdinalIgnoreCase))
            return null;

        string fullStreamString = (new StreamReader(controllerContext.HttpContext.Request.InputStream)).ReadToEnd();
        if (string.IsNullOrEmpty(fullStreamString))
            return null;

        var serializer = new JavaScriptSerializer()
        {
            MaxJsonLength = CustomJsonValueProviderFactory.GetMaxJsonLength()
        };
        return serializer.DeserializeObject(fullStreamString);
    }

    private static void AddToBackingStore(EntryLimitedDictionary backingStore, string prefix, object value)
    {
        IDictionary<string, object> strs = value as IDictionary<string, object>;
        if (strs != null)
        {
            foreach (KeyValuePair<string, object> keyValuePair in strs)
                CustomJsonValueProviderFactory.AddToBackingStore(backingStore, CustomJsonValueProviderFactory.MakePropertyKey(prefix, keyValuePair.Key), keyValuePair.Value);

            return;
        }

        IList lists = value as IList;
        if (lists == null)
        {
            backingStore.Add(prefix, value);
            return;
        }

        for (int i = 0; i < lists.Count; i++)
        {
            CustomJsonValueProviderFactory.AddToBackingStore(backingStore, CustomJsonValueProviderFactory.MakeArrayKey(prefix, i), lists[i]);
        }
    }

    private class EntryLimitedDictionary
    {
        private static int _maximumDepth;

        private readonly IDictionary<string, object> _innerDictionary;

        private int _itemCount;

        static EntryLimitedDictionary()
        {
            _maximumDepth = CustomJsonValueProviderFactory.GetMaximumDepth();
        }

        public EntryLimitedDictionary(IDictionary<string, object> innerDictionary)
        {
            this._innerDictionary = innerDictionary;
        }

        public void Add(string key, object value)
        {
            int num = this._itemCount + 1;
            this._itemCount = num;
            if (num > _maximumDepth)
            {
                throw new InvalidOperationException("The length of the string exceeds the value set on the maxJsonLength property.");
            }
            this._innerDictionary.Add(key, value);
        }
    }

    private static string MakeArrayKey(string prefix, int index)
    {
        return string.Concat(prefix, "[", index.ToString(CultureInfo.InvariantCulture), "]");
    }

    private static string MakePropertyKey(string prefix, string propertyName)
    {
        if (string.IsNullOrEmpty(prefix))
        {
            return propertyName;
        }
        return string.Concat(prefix, ".", propertyName);
    }

    private static int GetMaximumDepth()
    {
        int num;
        NameValueCollection appSettings = ConfigurationManager.AppSettings;
        if (appSettings != null)
        {
            string[] values = appSettings.GetValues("aspnet:MaxJsonDeserializerMembers");
            if (values != null && values.Length != 0 && int.TryParse(values[0], out num))
            {
                return num;
            }
        }
        return 1000;
    }

    private static int GetMaxJsonLength()
    {
        int num;
        NameValueCollection appSettings = ConfigurationManager.AppSettings;
        if (appSettings != null)
        {
            string[] values = appSettings.GetValues("aspnet:MaxJsonLength");
            if (values != null && values.Length != 0 && int.TryParse(values[0], out num))
            {
                return num;
            }
        }
        return 1000;
    }
}

Answer 18

修复 ASP.NET MVC：如果您只想针对导致问题的特定操作修复它，请更改此代码：

public JsonResult GetBigJson()
{
    var someBigObject = GetBigObject();
    return Json(someBigObject);
}

对此：

public JsonResult GetBigJson()
{
    var someBigObject = GetBigObject();
    return new JsonResult()
    {
        Data = someBigObject,
        JsonRequestBehavior = JsonRequestBehavior.DenyGet,
        MaxJsonLength = int.MaxValue
    };
}

并且功能应该是相同的，您可以只返回更大的 JSON 作为响应。

基于ASP.NET MVC源代码的说明：可以查看Controller.JsonASP.NET MVC源代码中的方法是什么

protected internal JsonResult Json(object data)
{
    return Json(data, null /* contentType */, null /* contentEncoding */, JsonRequestBehavior.DenyGet);
}

它正在调用其他Controller.Json方法：

protected internal virtual JsonResult Json(object data, string contentType, Encoding contentEncoding, JsonRequestBehavior behavior)
{
    return new JsonResult
    {
        Data = data,
        ContentType = contentType,
        ContentEncoding = contentEncoding,
        JsonRequestBehavior = behavior
    };
}

传递contentType和contentEncoding对象在哪里null。所以基本上调用return Json(object)控制器相当于调用return new JsonResult { Data = object, JsonRequestBehavior = sonRequestBehavior.DenyGet }. 您可以使用第二种形式和参数化JsonResult。

那么当你设置MaxJsonLength属性时会发生什么（默认情况下它是空的）？它传递给JavaScriptSerializer.MaxJsonLength属性，然后调用JavaScriptSerializer.Serialize方法：

JavaScriptSerializer serializer = new JavaScriptSerializer();
if (MaxJsonLength.HasValue)
{
    serializer.MaxJsonLength = MaxJsonLength.Value;
}

if (RecursionLimit.HasValue)
{
    serializer.RecursionLimit = RecursionLimit.Value;
}

response.Write(serializer.Serialize(Data));

当您不设置MaxJsonLenght序列化程序的属性时，它采用的 默认值仅为 2MB。