Extract list of attendees

google-docs-api.R

library(httr2)
library(googlesheets4)
library(purrr)

# Function that creates OAuth client for Google APIs
google_client <- function() {
  httr2::oauth_client(
    id = "[Client ID]",
    secret = "[Client secret]",
    token_url = "https://oauth2.googleapis.com/token",
    name = "howard-google-docs"
  )
}

# Create a new HTTP request
open_agenda_url <- "https://docs.googleapis.com/v1/documents/1sPVsWeBZKn9A8sbfM666aRYwxVq5Emrhp0ws_R5X1n4"
req <- request(open_agenda_url) 

# Authenticate and perform request
resp <- req %>% 
  req_oauth_auth_code(
    client = google_client(),
    auth_url = "https://accounts.google.com/o/oauth2/v2/auth",
    scope = "https://www.googleapis.com/auth/documents"
  ) %>% 
  req_perform()

# Extract content from Google Doc
resp_body_json <- resp %>% resp_body_json()
content <- resp_body_json$body$content

# Iterate and look for list of attendees
result <- c()

for (ii in seq(1, length(content))) {
  if (!is.null(content[[ii]]$paragraph$elements)) {
    for (jj in seq(1, length(content[[ii]]$paragraph$elements))) {
      if (!is.null(content[[ii]]$paragraph$elements[[jj]]$textRun$content) && 
          (content[[ii]]$paragraph$elements[[jj]]$textRun$content == "When you join the meeting, please enter your name and institution below:\n" |
           content[[ii]]$paragraph$elements[[jj]]$textRun$content == "When you join the meeting, please enter your name and institution below:")) {
        kk <- ii + 1
        while (!is.null(content[[kk]]$paragraph$elements[[1]]$textRun$content) && content[[kk]]$paragraph$elements[[1]]$textRun$content != "\n") {
          result <- c(result, content[[kk]]$paragraph$elements[[1]]$textRun$content)
          kk <- kk + 1
        }
      }
    }
  } else {
    next
  }
}

# Post-processing
result <- gsub("\n$", "", result)

# Final result
result

Obviously, you have to supply your Client ID and Client Secret from your Google Cloud account. Read this vignette for more info: https://httr2.r-lib.org/articles/oauth.html

In Google Cloud, when creating the "OAuth consent screen", make sure to add your email address to "Test users" so you don't get blocked by Google from authentication. According to Google, "OAuth access is restricted to the test users listed on your OAuth consent screen".

Fetch Client ID and Client Secret from Google Cloud

1. Create project on Google Cloud
2. Enable Google Docs API
3. Configure OAuth consent screen

Fill in the blanks as follows:

 User Type: "External"
 App name: "itn-metric"
 User support email: [email protected]
 Developer contact info: [email protected]
 ADD SCOPES: Check Scope `../auth/documents`
 IMPORTANT: Add test users: Your Google email address that you will use for this package.

4. Create Credentials -> Create OAuth client ID -> Application Type: Desktop app
5. Copy and paste Client ID and Client secret!