bug: fix get_covidhub_forecast_dates

R-packages/evalcast/DESCRIPTION

@@ -1,7 +1,7 @@
 Package: evalcast
 Type: Package
 Title: Tools For Evaluating COVID Forecasters
-Version: 0.3.2
+Version: 0.3.3
 Authors@R:
   c(
     person(given = "Daniel",
@@ -72,7 +72,6 @@ Imports:
     zoo,
     rlang,
     rvest,
-    xml2,
     ggplot2,
     zoltr,
     covidHubUtils,
@@ -82,7 +81,8 @@ Imports:
     fs,
     plyr,
     bettermc,
-    tidyr
+    tidyr,
+    httr
 Suggests:
     testthat,
     mockr,

R-packages/evalcast/NEWS.md

@@ -1,3 +1,8 @@
+# evalcast 0.3.3
+
+- Fix `get_covidhub_forecast_dates`, likely broken by GitHub website format
+  change, by refactoring it to use GitHub API
+
 # evalcast 0.3.2
 
 - Fix DESCRIPTION remotes so `remotes` and `devtools` work

R-packages/evalcast/R/get_covidhub_predictions.R

@@ -414,26 +414,49 @@ get_forecaster_predictions_alt <- function(covidhub_forecaster_name,
 
 #' Get available forecast dates for a forecaster on the COVID Hub
 #'
-#' Retrieves the forecast dates that a forecaster submitted to
-#' the [COVID Hub](https://github.com/reichlab/covid19-forecast-hub/).
+#' Retrieves the forecast dates that a forecaster submitted to the [COVID
+#' Hub](https://github.com/reichlab/covid19-forecast-hub/). Uses the [GitHub
+#' API](https://docs.github.com/en/rest/git/trees?apiVersion=2022-11-28#get-a-tree).
 #'
-#' @param forecaster_name String indicating of the forecaster
-#'   (matching what it is called on the COVID Hub).
+#' @param forecaster_name String indicating of the forecaster (matching what it
+#'   is called on the COVID Hub).
 #'
 #' @return vector of forecast dates
 #'
 #' @export
 get_covidhub_forecast_dates <- function(forecaster_name) {
-  url <- "https://github.com/reichlab/covid19-forecast-hub/tree/master/data-processed/"
-  out <- xml2::read_html(paste0(url, forecaster_name)) %>%
-    # In main element (identified by id), look for a `grid` object that has `row` children.
-    # Avoid using the full xpath due to fragility.
-    rvest::html_nodes(xpath = "//*[@id=\"js-repo-pjax-container\"]//div[@role=\"grid\" and .//@role=\"row\"]") %>%
-    rvest::html_text() %>%
-    stringr::str_remove_all("\\n") %>%
-    stringr::str_match_all(sprintf("(20\\d{2}-\\d{2}-\\d{2})-%s.csv",
-                                   forecaster_name))
-  lubridate::as_date(out[[1]][, 2])
+  url <- "https://api.github.com/repos/reichlab/covid19-forecast-hub/git/trees/master"
+
+  # Get the URL for the submissions folder "data-processed".
+  submissions_folder <- url %>%
+    httr::GET() %>%
+    httr::content() %>%
+    purrr::pluck("tree") %>%
+    magrittr::extract2(which(purrr::map_chr(., "path") == "data-processed"))
+
+  # Get the URL for the specified forecaster folder.
+  forecaster_folder <- submissions_folder$url %>%
+    httr::GET() %>%
+    httr::content() %>%
+    purrr::pluck("tree") %>%
+    magrittr::extract2(which(purrr::map_chr(., "path") == forecaster_name))
+
+  # Get the forecaster submission files.
+  submission_file_pattern <- sprintf("^(20\\d{2}-\\d{2}-\\d{2})-%s.csv$", forecaster_name)
+  submission_files <- forecaster_folder$url %>%
+    httr::GET() %>%
+    httr::content() %>%
+    purrr::pluck("tree") %>%
+    purrr::map_chr("path") %>%
+    magrittr::extract(stringr::str_detect(., submission_file_pattern))
+
+  # Extract the dates.
+  submission_dates <- submission_files %>%
+    # get first group of each match, requiring exactly one match per filename:
+    stringr::str_match(submission_file_pattern) %>%
+    magrittr::extract(, 2)
+
+  return(submission_dates)
 }