colearendt#39 first working version of is_json functions

NAMESPACE

@@ -18,6 +18,13 @@ export(enter_object)
 export(gather_array)
 export(gather_keys)
 export(is.tbl_json)
+export(is_json_array)
+export(is_json_logical)
+export(is_json_null)
+export(is_json_number)
+export(is_json_object)
+export(is_json_scalar)
+export(is_json_string)
 export(jlogical)
 export(jnumber)
 export(json_complexity)

R/is_json.R

@@ -0,0 +1,70 @@
+#' Factory to create \code{is_json} functions
+#' @param desired.types character vector of types we want to check for
+#' @return a function
+is_json_factory <- function(desired.types) {
+
+  function(.x) {
+    types <- .x %>% json_types %>% extract2("type")
+    types %in% desired.types
+  }
+
+}
+
+#' Predicates to test for specific JSON types in \code{\link{tbl_json}} objects
+#'
+#' These functions are often useful with \code{\link[dplyr]{filter}} to
+#' filter complex JSON by type before applying \code{\link{gather_keys}} or
+#' \code{\link{gather_array}}.
+#'
+#' @seealso \code{\link{json_types}} for creating a new column to identify the
+#'          type of every JSON document
+#' @name is-json
+#' @param .x a json string or \code{\link{tbl_json}} object
+#' @return a logical vector
+#' @examples
+#'
+#' # Test a simple example
+#' json <- '[1, "string", true, [1, 2], {"key": "value"}, null]' %>% gather_array
+#' json %>% is_json_number
+#' json %>% is_json_array
+#' json %>% is_json_scalar
+#'
+#' # Use with filter
+#' json %>% filter(is_json_object(.))
+#'
+#' # Combine with filter in advance of using gather_array
+#' companies[1:5] %>% gather_keys %>% filter(is_json_array(.))
+#' companies[1:5] %>% gather_keys %>% filter(is_json_array(.)) %>% gather_array
+#'
+#' # Combine with filter in advance of using gather_keys
+#' companies[1:5] %>% gather_keys %>% filter(is_json_object(.))
+#' companies[1:5] %>% gather_keys %>% filter(is_json_object(.)) %>% gather_keys("key2")
+NULL
+
+#' @rdname is-json
+#' @export
+is_json_string  <- is_json_factory("string")
+
+#' @rdname is-json
+#' @export
+is_json_number  <- is_json_factory("number")
+
+#' @rdname is-json
+#' @export
+is_json_logical <- is_json_factory("logical")
+
+#' @rdname is-json
+#' @export
+is_json_null    <- is_json_factory("null")
+
+#' @rdname is-json
+#' @export
+is_json_array   <- is_json_factory("array")
+
+#' @rdname is-json
+#' @export
+is_json_object  <- is_json_factory("object")
+
+#' @rdname is-json
+#' @export
+is_json_scalar  <- is_json_factory(c("string", "number", "logical"))

R/json_lengths.R

@@ -10,7 +10,7 @@
 #'
 #' @seealso \code{\link{json_complexity}} to compute the recursive length of
 #'          each value
-#' @param .x a json string or tbl_json object
+#' @param .x a json string or \code{\link{tbl_json}} object
 #' @param column.name the name to specify for the length column
 #' @return a \code{\link{tbl_json}} object
 #' @export

tests/testthat/test-is_json.R

@@ -0,0 +1,33 @@
+context("is_json")
+
+test_that("works for a simple example", {
+
+  json <- '[1, "string", true, [1, 2], {"key": "value"}, null]' %>%
+    gather_array
+
+  expect_identical(json %>% is_json_number  %>% which, 1L)
+  expect_identical(json %>% is_json_string  %>% which, 2L)
+  expect_identical(json %>% is_json_logical %>% which, 3L)
+  expect_identical(json %>% is_json_array   %>% which, 4L)
+  expect_identical(json %>% is_json_object  %>% which, 5L)
+  expect_identical(json %>% is_json_null    %>% which, 6L)
+  expect_identical(json %>% is_json_scalar  %>% which, c(1L, 2L, 3L))
+
+})
+
+test_that("works with filter", {
+
+  json <- '[1, "string", true, [1, 2], {"key": "value"}, null]' %>%
+    gather_array
+
+  expect_identical(
+    json %>% filter(is_json_array(.)),
+    json %>% slice(4)
+  )
+
+  expect_identical(
+    json %>% filter(is_json_object(.)),
+    json %>% slice(5)
+  )
+
+})