JSON Pointer · lesson 4 of 6 · When it doesn't work

Missing values & bad pointers

A pointer names exactly one value. If nothing is there, that is an error here (JSONPath, by contrast, returns an empty list). A pointer that isn't well-formed is a syntax error.

Example 1Nothing at that location

Document

{
  "store": {
    "book": [
      { "title": "Moby Dick", "price": 8.99 },
      { "title": "Ulysses", "price": 12.5 }
    ],
    "bicycle": { "color": "red" }
  }
}

Query

/store/book/9/title

/9 There is no element at index 9 — book has only 0 and 1 — so the whole pointer fails.

Result (it fails on purpose)

query error: no value at pointer '/store/book/9/title'

Try it in the playground

Example 2Not a pointer at all

Document

{
  "store": {
    "book": [
      { "title": "Moby Dick", "price": 8.99 },
      { "title": "Ulysses", "price": 12.5 }
    ],
    "bicycle": { "color": "red" }
  }
}

Query

store/book

store A pointer must be empty or start with /; this one starts with a letter.

Result (it fails on purpose)

query syntax error: a JSON pointer must be empty (whole document) or start with '/'

Try it in the playground