How do you POST data to a multi-page google form?

Question

I'm trying to auto-fill a google form via POST. However when I actually POST the data to it, only the first pages questions actually get filled.

Example Code:

    private static void PostToFormTest()
    {
        WebClient client = new WebClient();
        var keyValue = new NameValueCollection();
        keyValue.Add("entry.843521592", "Option 1");
        keyValue.Add("entry.901429584", "Test Right Now");
        keyValue.Add("entry.347619935", "Test Page 2");
        Uri uri = new Uri("https://docs.google.com/forms/d/1zuQxyoRUQ-jYwTf7wrPu9Wqln8ec7gfhzRbOILD3LGU/formResponse");
        byte[] response = client.UploadValues(uri, "POST", keyValue);
        string result = Encoding.UTF8.GetString(response);

    }

Responses Sheet:

https://docs.google.com/spreadsheets/d/1B4OSjQRQ37Q5Dt4mxMAx0wx5LfyajvWf_5rCY4lOvBU/edit?usp=sharing

Form:

https://docs.google.com/forms/d/1zuQxyoRUQ-jYwTf7wrPu9Wqln8ec7gfhzRbOILD3LGU/viewform

Answer 1

You are posting to a URL that only has 2 of the key value pairs:

// On page #1.
keyValue.Add("entry.843521592", "Option 1");
keyValue.Add("entry.901429584", "Test Right Now");

// On page #2.
keyValue.Add("entry.347619935", "Test Page 2");

The value for the second page cannot be added as the question does not exist when you post to the first page.