Send email via Gmail API

Will be based on:

https://github.com/jennybc/send-email-with-r#readme

Overview:

• Data frame #1: email recipients
  • one row per email recipient
  • email addresses
  • names
• Data frame #2: emails (one per piece of student homework, in example)
  • one per email to be sent
  • variables for MIME parts
• Join these two data frames
• Where does purrr come in?
  • pmap(edat, mime) to create one MIME-formatted email object per row/email
  • safely(gmailr::send_message) to create a “safe” version of the function that send messages … so one failure doesn’t derail things
  • map(email, safe_send_message) to send the email
  • transpose() and map_lgl() to inspect message success vs failure

In the meantime, here’s the clean script that is developed there:

suppressPackageStartupMessages(library(gmailr))
suppressPackageStartupMessages(library(dplyr))
suppressPackageStartupMessages(library(purrr))
library(readr)

addresses <- read_csv("addresses.csv")
marks <- read_csv("marks.csv")
my_dat <- left_join(marks, addresses)

this_hw <- "The Fellowship Of The Ring"
email_sender <- 'Peter Jackson <peter@tolkien.example.org>' # your Gmail address
optional_bcc <- 'Anonymous <anon@palantir.example.org>'     # for me, TA address
body <- "Hi, %s.

Your mark for %s is %s.

Thanks for participating in this film!
"

edat <- my_dat %>%
  mutate(
    To = sprintf('%s <%s>', name, email),
    Bcc = optional_bcc,
    From = email_sender,
    Subject = sprintf('Mark for %s', this_hw),
    body = sprintf(body, name, this_hw, mark)) %>%
  select(To, Bcc, From, Subject, body)
edat
write_csv(edat, "composed-emails.csv")

emails <- edat %>%
  map_n(mime)

## optional: use if you've created your own client id
use_secret_file("gmailr-tutorial.json")

safe_send_message <- safely(send_message)
sent_mail <- emails %>%
  map(safe_send_message)

saveRDS(sent_mail,
        paste(gsub("\\s+", "_", this_hw), "sent-emails.rds", sep = "_"))

errors <- sent_mail %>%
  transpose() %>%
  .$error %>%
  map_lgl(Negate(is.null))
sent_mail[errors]