How to allow for POST to an MVC5 Controller for large sets of data. - rest

Question

I have seen several posts addressing this issue or similar to this issue for requests or GETs. I am not having this problem getting the data from the server, its solely on the POST.
The Errors I get are
The JSON request was too large to be deserialized.
or either
Error during serialization or deserialization using the JSON JavaScriptSerializer. The length of the string exceeds the value set on the maxJsonLength property. Parameter name: input
I haven't been able to consistently determine which actions result in which error, but it is predominately the latter one.
In an effort to get the value of the MaxJsonSize value, on the Index method of the controller, I get this data and dump it into a viewbag to write to console on the client side. Every time it comes back at 10k (102400).
If I reduce the data package size, and still serialize as previously, I get no errors.
In fiddler I can inspect the package and all the JSON is deserializable in fiddler, so I don't see an issue in my JSON. Additionally if I console.log(data) chrome sees no problems with it either.
The VM in the controller is the same for both POST and GET. With the exception there is more data with the POST than the GET. To test this I got a huge data set from the server;
GeoJSON data for all 50 states. Following was the result.
GET Content-Length: 3229309 return 200
POST Content-Length: 2975244 return 500
The POST failed in this scenario and returned the second error listed previously.
I only changed the data minimally (one string) and don't know why when sent back its smaller, but the JSON for both the GET and the POST is virtually identical.
I've tried changing the web.config file:
<system.web.extensions>
<scripting>
<webServices>
<jsonSerialization maxJsonLength="2147483644"/>
</webServices>
</scripting>
</system.web.extensions>
I just added this to the end of my config file just prior to
I've also added a parameter in Settings.config
<add key="aspnet:MaxJsonDeserializerMembers" value="2147483644" />
I have also verified that this param loads as part of the application settings in IIS.
Is there something else I can try to change to allow for these large data sets to be sent in a POST.
As a last resort, I was going to pull all of the GeoJSON data out of the POST. However when a user navigates back and they haven't changed what they were mapping, we'd have to find all the GeoJSON data again, causing undue work on the server etc. I thought if I only had to fetch it once that would be best from an efficiency perspective.

Answer 1

I struggled with this too, nothing I changed in web.config helped, despite several SO answers looking relevant. They helped with returning large JSON data, but the large JSON post kept failing. In the end I found this:
increase maxJsonLength for JSON POST and used the solution there, and it worked for me.
Quoting from there :
the MVC json serializer does not look at the webconfig to get the max length (thats for asp.net web services). you need to use your own serializer. you override ExecuteResult and supply you own json serializer. to override the input, create a new JsonValueProviderFactory, then override ValueProvider in the controller to return your new json factory when its a json request.