add typechecks to sc_table_custom()

there are now several checks in place
that throw warnings if inputs in
sc_table_custom() or sc_recode() are
of the wrong schema-type or if other
inconsistencies are suspected. See
the section called "error handling"
in ?sc_table_custom for more details

some of those warnings might be
replaced with errors in the future

part of #33

R/table_custom.R

@@ -24,6 +24,21 @@
 #' it is possible to pass `sc_schema` objects (usually generated by
 #' [sc_schema_db()]) instead of ids in [sc_table_custom()] and [sc_recode()].
 #' If provided, the schema objects will be converted into ids via `$id`.
+#' @section Error handling:
+#' Unfortunately, the API gives fairly vague error messages in case a
+#' custom table request is ill defined. For this reason, [sc_table_custom()]
+#' applies some simple heuristics and throws warnings if inconsistencies
+#' in the provided parameters are recognized. The following conditions are
+#' currently checked
+#' * the parameter `db` is of type `DATABASE`
+#' * all entries in `measures` are of type `MEASURE`, `COUNT` or
+#' `STATFN`
+#' * all entries in `dimensions` are of type `VALUESET` or `FIELD`
+#' * all entries in `field` are of type `VALUESET` or `FIELD`
+#' * all entries in `map` are of type `VALUE`
+#' * all fields in `recodes` are also present in `dimensions`
+#' * the first two arguments of `sc_recode()` are consistent, i.e.
+#' if the provided `VALUE`s belong to the `VALUESET/FIELD`
 #' @examples
 #' sc_table_custom("str:database:detouextregsai")
 #'
@@ -66,15 +81,25 @@
 sc_table_custom <- function(db, measures = c(), dimensions = c(),
  language = c("en", "de"),
  add_totals = TRUE, key = NULL, recodes = NULL) {
- json_list <- list(database = as_id(db), measures = as.list(as_id(measures, TRUE)),
- dimensions = lapply(as_id(dimensions, TRUE), list))
+ db <- as_id(db)
+ measures <- as_id(measures, TRUE)
+ dimensions <- as_id(dimensions, TRUE)
+ json_list <- list(database = db, measures = as.list(measures),
+ dimensions = lapply(dimensions, list))
  if (!is.null(recodes)) {
  json_list$recodes <- recodes
  add_totals <- FALSE
  }
- #return(jsonlite::toJSON(json_list, auto_unbox = TRUE, pretty = TRUE))
  json <- jsonlite::toJSON(json_list, auto_unbox = TRUE, pretty = TRUE)
- #return(json)
+ if (!all(names(recodes) %in% dimensions))
+ warning("`recodes` and `dimensions` might be inconsistent")
+ if (!all(grepl("^str:valueset", dimensions) | grepl("^str:field", dimensions)))
+ warning("parameter `dimensions` is not of type `FIELD` or `VALUESET`")
+ if (!all(grepl("^str:measure", measures) | grepl("^str:statfn", measures) |
+ grepl("^str:count", measures)))
+ warning("parameter `measures` is not of type `MEASURE`, `STATFN` or `COUNT`")
+ if (!grepl("^str:database", db))
+ warning("parameter `db` is not of type `DATABASE`")
  response <- sc_table_json_post(json, language, add_totals, key)
  sc_table_class$new(response, toString(json))
 }
@@ -94,7 +119,7 @@ sc_recode <- function(field, map = NULL, total = FALSE) {
  return(stats::setNames(list(list(total = total)), as_id(field)))
  if (inherits(map, "sc_schema"))
  map <- list(map)
- stats::setNames(
+ recode <- stats::setNames(
  list(list(
  map = lapply(map, function(value) {
  I(as_id(value, TRUE))
@@ -103,6 +128,15 @@ sc_recode <- function(field, map = NULL, total = FALSE) {
  )),
  as_id(field)
  )
+ code_parent <- gsub("^.*:", "", names(recode))
+ codes_children <- unlist(recode[[1]]$map)
+ if (!all(grepl(code_parent, codes_children)))
+ warning("parameters `field` and `map` might be inconsistent")
+ if (!all(grepl("^str:value:", codes_children)))
+ warning("some entries in `map` are not of type VALUE")
+ if (!grepl("^str:valueset", names(recode)) && !grepl("^str:field", names(recode)))
+ warning("parameter `field` is not of type `FIELD` or `VALUESET`")
+ recode
 }
 
 as_id <- function(x, multiple = FALSE) {