Original data changed after using modified JsonValueProviderFactory to solve maxJsonLength exception - asp.net-mvc

Question

I'm working with some application designed using ASP.NET MVC.
Did spend lot of time trying to solve some problem, but do not have idea what to do to solve it.
As similar code shown below for big JSON will throw exception :
"Error during serialization or deserialization using the JSON JavaScriptSerializer. The length of the string exceeds the value set on the maxJsonLength property.
"
EXAMPLE :
$http.post('/API/PostData',aoData)...
where aoData equals 3K array of JSON, etc.
Added some solution suggested in many questions being asked on stackoverflow.
Did solve that problem just by :
Removing JsonValueProviderFactory from the ValueProviderFactories.Factories
And adding copy of the original class with simple modification such as :
EXAMPLE:
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;
}
}
}
And that solve the problem with maxJsonLength. Great! But...
If JSON contains property called ACTION, controller get data being changed. The ACTION property contains name of the controller's action instead of "MAR". The LargeJsonValueProviderFactory class does not change value of the ACION property. But if LargeJsonValueProviderFactory class shown above is not is use issue disappears.
EXAMPLE :
{
NR : 1200,
ACTION : "MAR",
.....
}
public ActionResult Save(PrsentationEntity aoData)
{
aoData.NR equals 1200 - OK
aoData.ACTION equals "Save" -Should be "MAR"
Do you have any ideas why I have that problem ?
Regards
Marcin

Answer 1

tl;dr
When configuring the application the original JsonValueProviderFactory should be replaced by the custom LargeJsonValueProviderFactory instead of added to the end of the collection.
Long version
You said you solved the problem by:
Removing JsonValueProviderFactory from the ValueProviderFactories.Factories
And adding copy of the original class with simple modification such as :
That's why the problem occurs.
The order of the factories on ValueProviderFactories.Factories does matter, but it's not generally discussed.
The original order is this:
private static readonly ValueProviderFactoryCollection _factories = new ValueProviderFactoryCollection()
{
new ChildActionValueProviderFactory(),
new FormValueProviderFactory(),
new JsonValueProviderFactory(),
new RouteDataValueProviderFactory(),
new QueryStringValueProviderFactory(),
new HttpFileCollectionValueProviderFactory(),
new JQueryFormValueProviderFactory()
};
If you just add your new provider to the end of the collection it won't be used if one of the other providers does the job (in this case it seems that RouteDataValueProviderFactory was used).