Mermaid rendering error in readme

A hackey fix is to include our own patched version of tar_mermaid() as a function within the R folder (which is what the current version of targets uses).

get_mermaid <- function(
    targets_only = FALSE,
    names = NULL,
    shortcut = FALSE,
    allow = NULL,
    exclude = ".Random.seed",
    outdated = TRUE,
    label = NULL,
    legend = TRUE,
    color = TRUE,
    reporter = targets::tar_config_get("reporter_outdated"),
    seconds_reporter = targets::tar_config_get("seconds_reporter"),
    callr_function = callr::r,
    callr_arguments = targets::tar_callr_args_default(callr_function),
    envir = parent.frame(),
    script = targets::tar_config_get("script"),
    store = targets::tar_config_get("store")
) {
  tar_assert_allow_meta("tar_mermaid", store = store) # THIS LINE WAS THE BUG
  force(envir)
  tar_assert_lgl(targets_only, "targets_only must be logical.")
  tar_assert_lgl(outdated, "outdated in tar_mermaid() must be logical.")
  tar_assert_in(label, c("time", "size", "branches"))
  tar_assert_lgl(legend)
  tar_assert_lgl(color)
  tar_assert_scalar(legend)
  tar_assert_scalar(color)
  tar_config_assert_reporter_outdated(reporter)
  tar_assert_callr_function(callr_function)
  tar_assert_list(callr_arguments, "callr_arguments mut be a list.")
  tar_assert_dbl(seconds_reporter)
  tar_assert_scalar(seconds_reporter)
  tar_assert_none_na(seconds_reporter)
  tar_assert_ge(seconds_reporter, 0)
  targets_arguments <- list(
    path_store = store,
    targets_only = targets_only,
    names_quosure = rlang::enquo(names),
    shortcut = shortcut,
    allow_quosure = rlang::enquo(allow),
    exclude_quosure = rlang::enquo(exclude),
    outdated = outdated,
    label = label,
    legend = legend,
    color = color,
    reporter = reporter,
    seconds_reporter = seconds_reporter
  )
  callr_outer(
    targets_function = tar_mermaid_inner,
    targets_arguments = targets_arguments,
    callr_function = callr_function,
    callr_arguments = callr_arguments,
    envir = envir,
    script = script,
    store = store,
    fun = "tar_mermaid"
  )
}

Then use that function instead of tar_mermaid within the README.Rmd. The only trick is we need to expose all of targets internal functions to the patched function. We can do that by copying the environment of tar_mermaid.

#  Giving our patch access to all of targets internal functions
environment(get_mermaid) <- environment(targets::tar_mermaid)

mer <- get_mermaid(targets_only = TRUE, outdated = FALSE,
                   legend = FALSE, color = FALSE,
                   store = "targets",
                   exclude = c("readme", ends_with("_targets")))
...
)

The problem was that the store variable wasn't getting passed into tar_assert_allow_meta() and the parent environment wasn't being enforced until the next line. Someone better at managing callr environments might be able to come up with a more elegant patch. Updating targets would be the best approach if possible.

@emmamendelsohn

ecohealthalliance / open-rvfcast

Mermaid rendering error in readme #88