Filter expression without parens

Setup

Selector: $[?@.key==42]

[
    {"key": 0},
    {"key": 42},
    {"key": -1},
    {"key": 1},
    {"key": 41},
    {"key": 43},
    {"key": 42.0001},
    {"key": 41.9999},
    {"key": 100},
    {"key": "some"},
    {"key": "42"},
    {"key": null},
    {"key": 420},
    {"key": ""},
    {"key": {}},
    {"key": []},
    {"key": [42]},
    {"key": {"key": 42}},
    {"key": {"some": 42}},
    {"some": "value"}
]

Results

Other responses

Bash (JSONPath.sh) 

[]

C (json-glib)

Not supported

Unable to compile selector `$[?@.key==42]': Invalid array index definition “?@.key==42]”

Cpp (jsoncons) 

[
  {
    "key": 42
  }
]

Dart (json_path) 

[
  {
    "key": 42
  }
]

Elixir (ExJsonPath)

Not supported

syntax error before: '@'

Elixir (jaxon) 

[]

Elixir (warpath) ¹

Not supported

Parser error: Invalid token on line 1, syntax error before: <<"@">>

Erlang (ejsonpath)

Not supported

syntax error before: '@'

Golang (github.com-PaesslerAG-jsonpath) ¹ 

[
  {
    "key": 42
  }
]

Golang (github.com-ohler55-ojg) 

[
  {
    "key": 42
  }
]

Golang (github.com-spyzhov-ajson) 

[]

Golang (github.com-theory-jsonpath) 

[
  {
    "key": 42
  }
]

Golang (github.com-vmware-labs-yaml-jsonpath)

Not supported

invalid array index [?@.key==42] before position 13: non-integer array index

Haskell (jsonpath) 

[
  {
    "key": 42
  }
]

JavaScript (Goessner) ²

Not found

jsonpath returned false, this might indicate an error

JavaScript (brunerd)

Not supported

JavaScript (json-p3) 

[
  {
    "key": 42
  }
]

JavaScript (jsonpath)

Not supported

Lexical error on line 1. Unrecognized text.
$[?@.key==42]
--^

JavaScript (jsonpath-plus) 

[]

JavaScript (jsonpathly)

Not supported

missing '(' at '@'

Java (com.github.jsurfer)

Not supported

line 1:2 token recognition error at: '?'
line 1:3 no viable alternative at input '[@'
org.antlr.v4.runtime.misc.ParseCancellationException

Java (com.jayway.jsonpath) ¹ ³

Not supported

SLF4J(W): No SLF4J providers were found.
SLF4J(W): Defaulting to no-operation (NOP) logger implementation
SLF4J(W): See https://www.slf4j.org/codes.html#noProviders for further details.
com.jayway.jsonpath.InvalidPathException: Could not parse token starting at position 1. Expected ?, ', 0-9, *

Kotlin (com.nfeld.jsonpathkt) ¹

Not supported

Unexpected char, char=?, index=2

Objective-C (SMJJSONPath) ¹ ³

Not supported

Could not parse token starting at position 1 . Expected ?, ', 0-9, *

PHP (Goessner) ²

Not found

jsonpath returned false, this might indicate an error

PHP (galbar-jsonpath)

Not supported

Invalid JSONPath error: 'Error in JSONPath near '?@.key==42''

PHP (remorhaz-jsonpath)

Not supported

Error: 'Failed to build AST from JSONPath query: $[?@.key==42]'

PHP (softcreatr-jsonpath)

Not supported

Error: 'Unable to parse token ?@.key==42 in expression: [?@.key==42]'

Perl (JSON-Path) 

[]

Python (jsonpath) ²

Not found

jsonpath returned false, this might indicate an error

Python (jsonpath-ng)

Not supported

JsonPathLexerError('Error on line 1, col 2: Unexpected character: ? ')

Python (jsonpath-rw)

Not supported

JsonPathLexerError('Error on line 1, col 2: Unexpected character: ? ')

Python (jsonpath2)

Not supported

line 1:3 missing '(' at '@'
ValueError("line 1:3 missing '(' at '@'")

Python (python-jsonpath) 

[
  {
    "key": 42
  }
]

Raku (JSON-Path)

Not supported

JSON path parse error at position 1

Rust (jsonpath)

Not supported

parsing error

Rust (jsonpath_lib)

Not supported

path error: 
$[?@.key==42]
^^^^

Rust (serde_json_path) 

[
  {
    "key": 42
  }
]

Scala (jsonpath)

Not supported

JPError(end of input expected)

Swift (Sextant)

Not supported

NOT_SUPPORTED

dotNET (Json.NET)

Not supported

Unexpected character while parsing path indexer: @

dotNET (JsonCons.JsonPath) 

[
  {
    "key": 42
  }
]

dotNET (JsonPath.Net) 

[
  {
    "key": 42
  }
]

dotNET (JsonPathLib) 

[]

dotNET (Manatee.Json)

Not supported

Unrecognized JSON Path element. Path up to error: '$'

Errors

Clojure (json-path) ¹ 

java.lang.NumberFormatException For input string: "@"

Golang (github.com-bhmj-jsonslice) ¹ ³ 

path: invalid character at 4

Golang (github.com-oliveagle-jsonpath) ¹ 

interface conversion: interface {} is nil, not string

Ruby (jsonpath) 

invalid value for Integer(): "@.key==42"

Rust (jsonpath_plus) 

Error Parsing JSON Path:
$[?@.key==42]
panic occurred

Footnotes