Why is my ajax post being truncated?

问题

I have just updated my mvc service to include greater error and logging. I have now got this exact error several times. But cannot replicate.

Unterminated string. Expected delimiter: ". Path 'Breadcrumbs[18].Params', line 1, position 59740. at Newtonsoft.Json.JsonTextReader.ReadStringIntoBuffer(Char quote) at

The Path is different each time, depending on what the user is sending to the server.

My ajax requests generally look like this:

$.ajax(myURL("SendBreadcrumbs"), {
            type: "POST",
            cache: false,
            data: { telemetry: telemetry.JSONify(), userID: currentUser, isMyVI: isMyVI }
        })

In these cases, userID and isMyVI (boolean) didnt exist and the telemetry string is truncated.

JSONify method is as follows:

self.JSONify = function () {
    var data = ko.mapping.toJSON(self, TelemetryMapping);
    return data;
}

This is knockoutJSs serializer.

Server Side:

public void SendBreadcrumbs(string telemetry, string userID = null, bool isMyVI = true)
{
    MyServiceAudit audit;
    Guid UserID;
    if (Guid.TryParse(userID, out UserID))
        audit = InsertAudit(UserID);
    else
        audit = InsertAudit(null);
    try
    {
        Models.Telemetry data = JsonConvert.DeserializeObject<Models.Telemetry>(telemetry);
        Controllers.Telemetry.UpdateTelemetry(data, isMyVI);
    }
    catch (Exception ex)
    {
         MyServiceAuditDB.FailAudit(audit.ID, ex.Message + " " + ex.StackTrace);
    }
}

I am completely stumped, i have tried updating the web.config on the server with larger maxvalues etc, to see its truncating on that side.

The only other difference i have in my ajax is a global timeout of 3mins.

Is this as simple as special characters not being handled on client side, or server side limitations, or is the data so large it gets chunked and server side doesn't know to wait for the next chunk?

回答1:

With help from a few comments, answers and finally got live failed data, I was able to resolve this.

It turned out that not only did the user use special characters, but also some of the static data sent down included this (GIGO - couldn't believe the state of some of our data).

Client Side Solution:

The encodeURIComponent() function encodes a URI component. This function encodes special characters. In addition, it encodes the following characters: , / ? : @ & = + $ #

$.ajax(myURL("SendBreadcrumbs"), {
        type: "POST",
        cache: false,
        data: { telemetry: encodeURIComponent(telemetry.JSONify()), userID: currentUser, isMyVI: isMyVI }
    })

Server Side Solution:

Converts a string to its unescaped representation. Uri.UnescapeDataString()

public void SendBreadcrumbs(string telemetry, string userID = null, bool isMyVI = true)
{
    MyServiceAudit audit;
    Guid UserID;
    if (Guid.TryParse(userID, out UserID))
        audit = InsertAudit(UserID);
    else
        audit = InsertAudit(null);
    try
    {
        Models.Telemetry data = JsonConvert.DeserializeObject<Models.Telemetry>(Uri.UnescapeDataString(telemetry));
        Controllers.Telemetry.UpdateTelemetry(data, isMyVI);
    }
    catch (Exception ex)
    {
         MyServiceAuditDB.FailAudit(audit.ID, ex.Message + " " + ex.StackTrace);
    }
}

Web Application Configuration:

I had a user getting a 500 error, due to trying to send 20 emails. I updated the config to include maximum request length (in kilobytes, example is 1GB) and max content length (in bytes, example is 1GB). Emails came through no issue. Couldn't believe it!

<appSettings>
    <add key="aspnet:MaxJsonDeserializerMembers" value="150000" />
</appSettings>
<system.web>
    <httpRuntime targetFramework="4.5" maxQueryStringLength="32768" maxUrlLength="65536" maxRequestLength="1048576" />
</system.web>
<system.webServer>
    <security>
        <requestFiltering>
            <requestLimits maxQueryString="32768" maxAllowedContentLength="1073741824"  />
        </requestFiltering>
    </security>
</system.webServer>
<system.web.extensions>
    <scripting>
        <webServices>
            <jsonSerialization maxJsonLength="2147483647" />
        </webServices>
    </scripting>
</system.web.extensions>

回答2:

I suggest you using the fiddler for getting the rough idea of what data is actually sent. It is surely the problem from de-serialization and your code looks completely fine. Size of the data should not be an issue here, get some raw view of data and you should be fine.

Also see if the JSONify() return the data formatted correctly without escaping the character sequence.

回答3:

Try using encodeURIComponent for the content entered by user.

回答4:

You do not specify which version of jQuery you're using, but when we assume a stable release we can be sure that the necessary encoding and escaping in the downline of $.ajax() is flawless.

If request length was the cause, we would see a http error on client side and no call of the server-side function ("max request length exceeded"). This is supported by your observation that requests with longer strings can succeed while shorter ones can fail.

I'd suggest two actions:

1) To reduce fragmentation, layering and possible misleading diagnoses, do not JSONify just the telemetry. Construct your object out of telemetry, userID and isMyVi, then JSONify that as a whole (that means, include the meta data in the TelemetryMapping description if possible)

2) Inspect the value of telemetry.JSONify() at runtime client-side. If you find that the truncation is caused by this, focus on knockoutJS version and integrity, or replace. As @Destrif points out in their comment, https://stackoverflow.com/a/21565447/1132334 suggests that it may not be part of knockoutJS's tasks to escape double quotes, backslashes and slashes -

which may be as simple as wrapping the call in another escape():

self.JSONify = function () {
    var data = escape(ko.mapping.toJSON(self, TelemetryMapping));
    return data;
}

来源：https://stackoverflow.com/questions/41898747/why-is-my-ajax-post-being-truncated

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