Fix for breaking API change in jsonlite 0.9.22. See jeroen/jsonlite#1…

…30 (comment).

`

NEWS.md

@@ -1,6 +1,7 @@
 ### crunch 1.10.3 (under development)
 * Fix `as.data.frame`/`as.environment` for `CrunchDataset` when a variable alias contained an apostrophe.
 * Better print method for project `MemberCatalog`.
+* Fix for [change in 'jsonlite' API](https://github.com/jeroenooms/jsonlite/issues/130#issuecomment-225971209) in its v0.9.22
 
 ### crunch 1.10.2
 * `exportDataset` to download a CSV or SAV file of a dataset. `write.csv` convenience method for CSV export.

R/json.R

@@ -38,6 +38,7 @@ setMethod("jsonprep", "OrderGroup", .jsonprep.ordergroup)
 ##' @rdname tojson-crunch
 ##' @export
 toJSON <- function (x, ...) {
+    if (is.null(x)) return(jsonlite::toJSON(emptyObject()))
     out <- jsonlite::toJSON(jsonprep(x), auto_unbox=TRUE, null="null", na="null", force=TRUE, ...)
     # cat(out)
     return(out)

tests/testthat/test-active-filter.R

@@ -8,6 +8,9 @@ with_mock_HTTP({
     test_that("A clean dataset has NULL activeFilter", {
         expect_null(activeFilter(ds))
     })
+    test_that("A null filter becomes valid JSON", {
+        expect_equal(unclass(toJSON(zcl(activeFilter(ds)))), "{}")
+    })
     test_that("Getting a variable from a clean dataset has NULL activeFilter", {
         expect_null(activeFilter(ds$gender))
     })

tests/testthat/test-misc.R

@@ -90,6 +90,11 @@ test_that("null function always returns null", {
     expect_null(null(stop("yo!")))
 })
 
+test_that("JSON behavior for NULL (handle jsonlite API change in 0.9.22)", {
+    expect_equal(unclass(toJSON(NULL)), "{}")
+    expect_equal(unclass(toJSON(list(x=NULL))), '{"x":null}')
+})
+
 test_that("setIfNotAlready", {
     with(temp.options(crunch.test.opt1="previous",
                       crunch.test.opt2=NULL,