[Index expression] does not apply to array returned by [?filter expression]

[gmaFFFFF]

Hello,

$.books[[email protected]>22] will return an book array:

[
  {
    "category": "fiction",
    "title": "A Wild Sheep Chase",
    "author": "Haruki Murakami",
    "price": 22.72
  },
  {
    "category": "fiction",
    "title": "The Night Watch",
    "author": "Sergei Lukyanenko",
    "price": 23.58
  },
  {
    "category": "memoir",
    "title": "The Night Watch",
    "author": "David Atlee Phillips",
    "price": 260.90
  }
]

$.books[[email protected]>22][0] will retrun an empty array []
Many people think $.books[[email protected]>22][0] should return a book:

{
    "category": "fiction",
    "title": "A Wild Sheep Chase",
    "author": "Haruki Murakami",
    "price": 22.72
}

It looks like this problem affects all similar libraries - example

[danielaparker]

JSONPath basically collects values that are already in the original JSON document, it doesn't create new values, and as the last step, it appends all the values that it has collected into a result array. In JSONPath, the index operator can only be applied to items that are already arrays in the original JSON document, e.g., $.books[0]. The result array isn't created until all querying is done, it can't itself be queried against.

By contrast, there are other JSON query languages that do support the creation of new arrays as intermediate values, and these can be queried against. For example, the JMESPath expression

(books[?price > `8`])[0]

and the JSONAta expression

$.books[price > 8][0]

both produce

{
  "category": "fiction",
  "title": "A Wild Sheep Chase",
  "author": "Haruki Murakami",
  "price": 22.72
}

(JsonCons.Net has an implementation of JMESPath)

[gmaFFFFF]

Thanks for the clarification