AddBodyParameter sometimes doesn't work on first try

[bdr99]

I have a spreadsheet which sends a POST request that contains body parameters. I am using Fiddler to analyze the traffic sent by VBA-Web. Occasionally, my requests are being sent without the body parameters. When this happens, the request is just sent with an empty body and Content-Length is 0. It happens almost every time I first open the spreadsheet. It always works if I try again a second time. It is very frustrating because it is intermittent. It is as if the Request.AddBodyParameter lines in my code are being ignored. I know those lines are running though, because if I set a breakpoint, on them, it does stop. Why could this be happening?

I am using 64-bit Excel 2013 on Windows 8.1.

[timhall]

Interesting, I have been getting this occasionally with the test suite, but I figured (incorrectly) that it was a problem with httpbin.org. I'll dig in and see what I can find.

[bdr99]

Thanks. It's reassuring to hear that you have also encountered this bug.

[bdr99]

Hi @timhall , I was just wondering if you've made any progress on this. It is a frustrating issue that I deal with every day, and even a temporary solution (commenting out a line of code, etc) would be very helpful. Thanks.

[timhall]

@bdr99 I haven't been able to reproduce it consistently to really debug what is happening. If you're getting it everyday, I could use some help debugging:

1. Set WebHelpers.EnableLogging = True before the request is executed and then check if the body is being sent in the logs in the Immediate Window ctrl + g
2. At the end of WebRequest.AddBodyParameter (~689), check the current Body value with Debug.Print Me.Body
3. In WebClient.Execute (~275), check Request.Body before Send with Debug.Print Request.Body

[bdr99]

Sure, I'd be happy to help. I'll try these later when I have some time. Thanks.

[bdr99]

While I was trying to do this debugging, I ran into another problem. I started with a blank copy of VBA-Web - Blank.xlsm and added the following code to a new sub:

Dim Client As New WebClient, request As New WebRequest, response As WebResponse

Client.BaseUrl = "http://httpbin.org"
Client.EnableAutoProxy = True

request.Resource = "post"
request.Method = HttpPost
request.AddBodyParameter "param1", "test1"
request.AddBodyParameter "param2", "test2"
request.AddBodyParameter "param3", "test3"

Set response = Client.Execute(request)

This code works fine, sending the following request body:

{"param1":"test1","param2":"test2","param3":"test3"}

But as soon as I add Debug.Print Me.Body to the end of WebRequest.AddBodyParameter, it then only sends the first parameter:

{"param1":"test1"}

This made no sense at first. But then I looked at line 451 in WebRequest (Public Property Get Body() As Variant). This converts the body to a string and saves it in web_pConvertedBody. If this string already exists, however, it will use the already stored value from web_pConvertedBody. Therefore, subsequent calls to the Body of the WebRequest will always return the same value, even if additional body parameters are added. It seems like it should always generate a new value every time the Get Body() is called. I'm not even sure why the value needs to be stored in web_pConvertedBody.

I'm not sure if this problem is related to (or maybe even the cause of) my original problem, but fixing it would certainly make it easier to debug that problem.

[timhall]

That is definitely a bug and I'll fix it shortly. I too am curious if that is the root cause, it certainly could lead to some unexpected behavior.

[bdr99]

Thanks. Once this bug is fixed, I will try to help you debug the original issue I was dealing with, if it still exists.

[timhall]

Ok, it's been fixed in v4.0.14

[bdr99]

I'm actually running into a new problem now. Somehow my WebRequest bodies are becoming malformed. I added Debug.Print "body=""" & Body & """" to the end of the Public Property Get Body() As Variant line in WebRequest at line 463. This is what I'm getting:

At first I didn't even realize that this was a separate problem because it causes my code to fail in the same way that the original problem did. I can't find any pattern as to when this one happens and when it doesn't happen. Any help would be appreciated.

[timhall]

Wow, that's very strange. What Format/RequestFormat/custom formatter are you using? (the default is WebFormat.Json)

[bdr99]

I am using the FormUrlEncoded format with three body parameters.

[timhall]

Are you able to send me the parameters/Workbook or a portion of them so that I can try to reproduce locally? (my email is in the code headers) My best guess is some implicit conversion issues between Variant and String, but I would need to see more to fully diagnosis the bug.