json_extract: Extract an element from JSON
In jsontools: Working with JSON Vectors

Description Usage Arguments Value Examples

Extract an element at a given path.

json_extract(
  x,
  path,
  ptype = NULL,
  default = NULL,
  na = NA,
  wrap_scalars = FALSE,
  bigint_as_char = bigint_default()
)

`x`	A JSON vector.
`path`	Path to element. This must be a valid JSONpath expression. For example `"$.a.b[0]` extracts the `1` in `{"a": {"b": [1, 2]}}`.
`ptype`	Output type. If `NULL`, the default, the output type is determined by computing the common type across all elements. Use `new_json_array()` resp. `new_json_object()` if you know every element is an array resp. object. Mind that the return type will only be `json2`.
`default`	Default value if path doesn't exist or element at path is empty.
`na`	Default value if element of `x` is `NA`.
`wrap_scalars`	Should scalar values be wrapped? Note that scalars are only wrapped if either `ptype` is `new_json_array()` or `json2` vector. `ptype` is `NULL` and the elements are a mix of scalar values and arrays.
`bigint_as_char`	Convert big integers to character? The option `jsontools.bigint_as_char` is used as default.

A vector with class given by ptype and length equal to x. Mind that for new_json_array() and new_json_object() the return type will only be json2.

x1 <- '{"a": 1, "b": 2}'
json_extract(x1, "$.a")
json_extract('{"a": {"b": 1}}', "$.a")

# `NA` values stay `NA` ...
json_extract(c(NA_character_, x1), "$.a")
# ... but can return the value of `na` instead.
json_extract(c(NA_character_, x1), "$.a", na = 3)

# missing paths error by default ...
try(json_extract(x1, "$.c"))
# ... but can be replaced by the value of `default` instead.
json_extract(x1, "$.c", default = "not there")

# make sure to error if you don't get back an array
json_extract('{"a": [1]}', "$.a", ptype = new_json_array())
try(json_extract('{"a": {"b": 1}}', "$.a", ptype = new_json_array()))