validate the selection param on R side (#795)

NEWS.md

@@ -10,6 +10,8 @@
 
 - Now the `server` argument in `renderDT()` is reactive in Shiny (thanks, @shrektan, #794).
 
+- Incorrect `selection` param now triggers a clear error message on the R side (thanks, @shrektan, #795).
+
 # CHANGES IN DT VERSION 0.13
 
 ## BUG FIXES

R/datatables.R

@@ -263,7 +263,7 @@ datatable = function(
     if (grepl('^row', selection$target) && is.character(selection$selected) && length(rn)) {
       selection$selected = match(selection$selected, rn)
     }
-    params$selection = selection
+    params$selection = validateSelection(selection)
     # warn if the Select ext is used but selection is not set to none
     if ('Select' %in% extensions && selection$mode != 'none') warning(
       "The Select extension can't work properly with DT's own ",
@@ -317,6 +317,23 @@ datatable = function(
   )
 }
 
+validateSelection = function(x) {
+  err = character()
+  if (length(x$mode) != 1L || !x$mode %in% c('none', 'single', 'multiple'))
+    err = c(err, "- `mode` must be one of 'none', 'single' and 'multiple'")
+  if (length(x$target) != 1L || !x$target %in% c('row', 'column', 'row+column', 'cell'))
+    err = c(err, "- `target` must be one of 'row', 'column', 'row+column' and 'cell'")
+  if (length(x$selected)) {
+    if (x$target == 'row+column' && (!is.list(x$selected) || !names(x$selected) %in% c('rows', 'cols')))
+      err = c(err, "- when `target` is 'row+column', `selected` must be a list in the form `list(rows = 1, cols = 2)`")
+    if (x$target == 'cell' && (!is.matrix(x$selected) || ncol(x$selected) != 2L))
+      err = c(err, "- when `target` is 'cell', `selected` must be a 2-col matrix")
+  }
+  if (length(err))
+    stop(paste0(c("the `selection` argument is incorrect:", err), collapse = '\n'), call. = FALSE)
+  x
+}
+
 appendColumnDefs = function(options, def) {
   defs = options[['columnDefs']]
   if (is.null(defs)) defs = list()

tests/testit/test-datatables.R

@@ -1,5 +1,40 @@
 library(testit)
 
+assert('validateSelection() works', {
+  (has_error(
+    validateSelection(list(mode = 'a'))
+  ))
+  (!has_error(
+    validateSelection(list(mode = 'single', target = 'row'))
+  ))
+  # check selected when target is row+column
+  (!has_error(
+    validateSelection(list(mode = 'none', target = 'row+column'))
+  ))
+  (has_error(
+    validateSelection(list(mode = 'none', target = 'row+column', selected = 1))
+  ))
+  (!has_error(
+    validateSelection(list(mode = 'none', target = 'row+column', selected = list(rows = 3:4)))
+  ))
+  (!has_error(
+    validateSelection(list(mode = 'none', target = 'row+column', selected = list(cols = 3:4)))
+  ))
+  # check selected when target is cell
+   (!has_error(
+    validateSelection(list(mode = 'none', target = 'cell'))
+  ))
+  (has_error(
+    validateSelection(list(mode = 'none', target = 'cell', selected = 1))
+  ))
+  (has_error(
+    validateSelection(list(mode = 'none', target = 'cell', selected = cbind(1)))
+  ))
+  (!has_error(
+    validateSelection(list(mode = 'none', target = 'cell', selected = cbind(1, 2)))
+  ))
+})
+
 assert('appendColumnDefs() works', {
   (appendColumnDefs(list(), 1) %==% list(columnDefs = list(1)))
   (appendColumnDefs(list(a = 1), 2) %==% list(a = 1, columnDefs = list(2)))