Load haven formats as data frames

DESCRIPTION

@@ -35,6 +35,7 @@ Suggests:
     blastula,
     emayili,
     readr,
-    readxl
+    readxl,
+    haven
 Roxygen: list(markdown=TRUE, r6=FALSE)
-RoxygenNote: 7.2.1
+RoxygenNote: 7.3.3

R/ms_drive_item.R

@@ -26,7 +26,7 @@
 #' - `get_parent_folder()`: Get the parent folder for this item, as a drive item object. Returns the root folder for the root. Not supported for remote items.
 #' - `get_path()`: Get the absolute path for this item, as a character string. Not supported for remote items.
 #' - `is_folder()`: Information function, returns TRUE if this item is a folder.
-#' - `load_dataframe(delim=NULL, ...)`: Download an Excel or text file and return its contents as a data frame. See 'Saving and loading data' below.
+#' - `load_dataframe(delim=NULL, ...)`: Download an Excel, SAS, Stata, SPSS, or text file and return its contents as a data frame. See 'Saving and loading data' below.
 #' - `load_rds()`: Download a .rds file and return the saved object.
 #' - `load_rdata(envir)`: Load a .RData or .Rda file into the specified environment.
 #' - `save_dataframe(df, file, delim=",", ...)` Save a dataframe to a delimited file.
@@ -81,8 +81,8 @@
 #'
 #' @section Saving and loading data:
 #' The following methods are provided to simplify the task of loading and saving datasets and R objects.
-#' - `load_dataframe` downloads an Excel (.xlsx or .xls extension) or text file and returns its contents as a data frame. Loading Excel files uses the `readxl::read_excel` function, and so requires that the readxl package is installed. For a text file, you can specify the delimiter with the `delim` argument; if omitted, this is "," if the file extension is .csv, ";" if the file extension is .csv2, and a tab otherwise. If the readr package is installed, the `readr::read_delim` function is used to parse text files, otherwise `utils::read.delim` is used. You can supply other arguments to these functions via the `...` argument.
-#' - `save_dataframe` is the inverse of `load_dataframe`: it uploads the given data frame to a folder item. Specify the delimiter with the `delim` argument. The `readr::write_delim` function is used to serialise the data if that package is installed, and `utils::write.table` otherwise. Note that unlike loading, saving to an Excel file is not supported.
+#' - `load_dataframe` downloads an Excel (.xlsx or .xls extension), SAS (.sas7bdat, .sas7bcat, or .xpt), Stata (.dta), SPSS (.sav or .por), or text file and returns its contents as a data frame. Loading Excel files uses the `readxl::read_excel` function, and so requires that the readxl package is installed. Loading SAS, Stata, or SPSS files uses the corresponding `haven::read_` function for each extension, and so requires that the haven package be installed. For a text file, you can specify the delimiter with the `delim` argument; if omitted, this is "," if the file extension is .csv, ";" if the file extension is .csv2, and a tab otherwise. If the readr package is installed, the `readr::read_delim` function is used to parse text files, otherwise `utils::read.delim` is used. You can supply other arguments to these functions via the `...` argument.
+#' - `save_dataframe` is the inverse of `load_dataframe`: it uploads the given data frame to a folder item. Specify the delimiter with the `delim` argument. The `readr::write_delim` function is used to serialise the data if that package is installed, and `utils::write.table` otherwise. Note that unlike loading, saving to an Excel, SAS, Stata, or SPSS file is not supported.
 #' - `load_rds` downloads a .rds file and returns its contents as an R object. It is analogous to the base `readRDS` function but for OneDrive/SharePoint drive items.
 #' - `save_rds` uploads a given R object as a .rds file, analogously to `saveRDS`.
 #' - `load_rdata` downloads a .RData or .Rda file and loads its contents into the given environment. It is analogous to the base `load` function but for OneDrive/SharePoint drive items.
@@ -422,6 +422,23 @@ public=list(
         private$assert_is_file()
         ext <- tolower(tools::file_ext(self$properties$name))
 
+        if(ext %in% c("sav","zsav","por","sas7bdat","sas7bcat","dta","xpt"))
+        {
+            if(!requireNamespace("haven"))
+                stop("The haven package must be installed to load a file in a SAS, Stata, or SPSS format")
+            infile <- paste0(tempfile(),".",ext)
+            on.exit(unlink(infile))
+            self$download(dest=infile)
+            if(ext %in% c("sav","zsav","por"))
+                return(haven::read_spss(infile,...))
+            if(ext %in% c("sas7bdat","sas7bcat"))
+                return(haven::read_sas(infile,...))
+            if(ext == "dta")
+                return(haven::read_dta(infile,...))
+            if(ext == "xpt")
+                return(haven::read_xpt(infile,...))
+        }
+
         if(ext %in% c("xls", "xlsx"))
         {
             if(!requireNamespace("readxl"))