@swaggerexpert/jsonpath is a parser and validator for RFC 9535 Query Expressions for JSON - JSONPath.
The development of this library contributed to the identification and formal submission of following erratas against the RFC 9535:
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You can install @swaggerexpert/jsonpath using npm:
$ npm install @swaggerexpert/jsonpath@swaggerexpert/jsonpath currently supports parsing and validation.
Both parser and validator are based on a superset of ABNF (SABNF)
and use apg-lite parser generator.
Parsing a JSONPath Query expression is as simple as importing the parse function and calling it.
import { parse } from '@swaggerexpert/jsonpath';
const parseResult = parse('$.store.book[0].title');parseResult variable has the following shape:
{
result: <ParseResult['result]>,
tree: <ParseResult['tree']>,
stats: <ParseResult['stats']>,
trace: <ParseResult['trace']>,
}
TypeScript typings are available for all fields attached to parse result object returned by the parse function.
Normalized Path is a JSONPath query with restricted syntax. A Normalized Path represents the identity of a node in a specific value. There is precisely one Normalized Path identifying any particular node in a value. Normalized Paths provide a predictable format that simplifies testing and post-processing of nodelists, e.g., to remove duplicate nodes. Normalized Paths use the canonical bracket notation, rather than dot notation. Single quotes are used in Normalized Paths to delimit string member names. This reduces the number of characters that need escaping when Normalized Paths appear in strings delimited by double quotes.
Parsing in normalized path mode can be enabled by setting normalized option to true.
import { parse } from '@swaggerexpert/jsonpath';
parse("$['a']", { normalized: true });
parse("$[1]", { normalized: true });
parse("$[2]", { normalized: true });
parse("$['a']['b'][1]", { normalized: true });
parse("$['\\u000b']", { normalized: true });@swaggerexpert/jsonpath provides several translators to convert the parse result into different tree representations.
Concrete Syntax Tree (Parse tree) representation is available on parse result
when instance of CSTTranslator is provided via a translator option to the parse function.
CST is suitable to be consumed by other tools like IDEs, editors, etc...
import { parse, CSTTranslator } from '@swaggerexpert/jsonpath';
const { tree: CST } = parse('$.store.book[0].title', { translator: new CSTTranslator() });CST tree has a shape documented by TypeScript typings (CSTTree).
Same as CST, but optimizes the tree for more optimized representation. By default, it collapses
fragmented single-quoted, double-quoted or normal-single-quoted nodes into a single node.
text, segments and singular-query-segments nodes, when empty, are removed from the tree.
import { parse, CSTOptimizedTranslator } from '@swaggerexpert/jsonpath';
const { tree: CST } = parse('$.store.book[0].title', { translator: new CSTOptimizedTranslator() });Default translator. Abstract Syntax Tree representation is available on parse result
by default or when instance of ASTTranslator is provided via a translator option to the parse function.
AST is suitable to be consumed by implementations that need to analyze the structure of the JSONPath expression
or for building a custom JSONPath evaluation engine.
import { parse } from '@swaggerexpert/jsonpath';
const { tree: AST } = parse('$.store.book[0].title');or
import { parse, ASTTranslator } from '@swaggerexpert/jsonpath';
const { tree: AST } = parse('$.store.book[0].title', { translator: new ASTTranslator() });AST tree has a shape documented by TypeScript typings (ASTTree).
import { parse, XMLTranslator } from '@swaggerexpert/jsonpath';
const { tree: XML } = parse('$.store.book[0].title', { translator: new XMLTranslator() });parse function returns additional statistical information about the parsing process.
Collection of the statistics can be enabled by setting stats option to true.
import { parse } from '@swaggerexpert/jsonpath';
const { stats } = parse('$.store.book[0].title', { stats: true });
stats.displayStats(); // returns operator stats
stats.displayHits(); // returns rules grouped by hit countparse function returns additional tracing information about the parsing process.
Tracing can be enabled by setting trace option to true. Tracing is essential
for debugging failed matches or analyzing rule execution flow.
import { parse } from '@swaggerexpert/jsonpath';
const { result, trace } = parse('$fdfadfd', { trace: true });
result.success; // returns false
trace.displayTrace(); // returns trace informationBy combining information from result and trace, it is possible to analyze the parsing process in detail
and generate a messages like this: 'Syntax error at position 1, expected "[", ".", ".."'. Please see this
test file for more information how to achieve that.
@swaggerexpert/jsonpath provides a test function to validate JSONPath expressions.
import { test } from '@swaggerexpert/jsonpath';
test('$.store.book[0].title'); // => true
test('$$'); // => falseNormalized paths can be validated by setting normalized option to true.
import { test } from '@swaggerexpert/jsonpath';
test("$['a']", { normalized: true }); // => true
test('$.store.book[0].title', { normalized: true }); // => false@swaggerexpert/jsonpath provides a structured error class hierarchy,
enabling precise error handling across JSONPath operations, including parsing.
import { JSONPathError, JSONPathParseError } from '@swaggerexpert/jsonpath';JSONPathError is the base class for all JSONPath errors.
New grammar instance can be created in following way:
import { Grammar } from '@swaggerexpert/jsonpath';
const grammar = new Grammar();To obtain original ABNF (SABNF) grammar as a string:
import { Grammar } from '@swaggerexpert/jsonpath';
const grammar = new Grammar();
grammar.toString();
// or
String(grammar);JSONPath is defined by the following ABNF syntax
; JSONPath: Query Expressions for JSON
; https://www.rfc-editor.org/rfc/rfc9535
; https://www.rfc-editor.org/rfc/rfc9535#section-2.1.1
jsonpath-query = root-identifier segments
segments = *(S segment)
B = %x20 / ; Space
%x09 / ; Horizontal tab
%x0A / ; Line feed or New line
%x0D ; Carriage return
S = *B ; optional blank space
; https://www.rfc-editor.org/rfc/rfc9535#section-2.2.1
root-identifier = "$"
; https://www.rfc-editor.org/rfc/rfc9535#section-2.3
selector = name-selector /
wildcard-selector /
slice-selector /
index-selector /
filter-selector
; https://www.rfc-editor.org/rfc/rfc9535#section-2.3.1.1
name-selector = string-literal
string-literal = dquote *double-quoted dquote / ; "string", MODIFICATION: surrogate text rule used
squote *single-quoted squote ; 'string', MODIFICATION: surrogate text rule used
double-quoted = unescaped /
%x27 / ; '
ESC %x22 / ; \"
ESC escapable
single-quoted = unescaped /
%x22 / ; "
ESC %x27 / ; \'
ESC escapable
ESC = %x5C ; \ backslash
unescaped = %x20-21 / ; see RFC 8259
; omit 0x22 "
%x23-26 /
; omit 0x27 '
%x28-5B /
; omit 0x5C \
%x5D-D7FF /
; skip surrogate code points
%xE000-10FFFF
escapable = %x62 / ; b BS backspace U+0008
%x66 / ; f FF form feed U+000C
%x6E / ; n LF line feed U+000A
%x72 / ; r CR carriage return U+000D
%x74 / ; t HT horizontal tab U+0009
"/" / ; / slash (solidus) U+002F
"\" / ; \ backslash (reverse solidus) U+005C
(%x75 hexchar) ; uXXXX U+XXXX
hexchar = non-surrogate /
(high-surrogate "\" %x75 low-surrogate)
non-surrogate = ((DIGIT / "A"/"B"/"C" / "E"/"F") 3HEXDIG) /
("D" %x30-37 2HEXDIG )
high-surrogate = "D" ("8"/"9"/"A"/"B") 2HEXDIG
low-surrogate = "D" ("C"/"D"/"E"/"F") 2HEXDIG
HEXDIG = DIGIT / "A" / "B" / "C" / "D" / "E" / "F"
; https://www.rfc-editor.org/rfc/rfc9535#section-2.3.2.1
wildcard-selector = "*"
; https://www.rfc-editor.org/rfc/rfc9535#section-2.3.3.1
index-selector = int ; decimal integer
int = "0" /
(["-"] DIGIT1 *DIGIT) ; - optional
DIGIT1 = %x31-39 ; 1-9 non-zero digit
; https://www.rfc-editor.org/rfc/rfc9535#section-2.3.4.1
slice-selector = [start S] colon S [end S] [colon [S step ]] ; MODIFICATION: surrogate text rule used
start = int ; included in selection
end = int ; not included in selection
step = int ; default: 1
; https://www.rfc-editor.org/rfc/rfc9535#section-2.3.5.1
filter-selector = questionmark S logical-expr ; MODIFICATION: surrogate text rule used
logical-expr = logical-or-expr
logical-or-expr = logical-and-expr *(S disjunction S logical-and-expr) ; MODIFICATION: surrogate text rule used
; disjunction
; binds less tightly than conjunction
logical-and-expr = basic-expr *(S conjunction S basic-expr) ; MODIFICATION: surrogate text rule used
; conjunction
; binds more tightly than disjunction
basic-expr = paren-expr /
comparison-expr /
test-expr
paren-expr = [logical-not-op S] left-paren S logical-expr S right-paren ; MODIFICATION: surrogate text rule used
; parenthesized expression
logical-not-op = "!" ; logical NOT operator
test-expr = [logical-not-op S]
(filter-query / ; existence/non-existence
function-expr) ; LogicalType or NodesType
filter-query = rel-query / jsonpath-query
rel-query = current-node-identifier segments
current-node-identifier = "@"
comparison-expr = comparable S comparison-op S comparable
literal = number / string-literal /
true / false / null
comparable = singular-query / ; singular query value
function-expr / ; ValueType
literal
; MODIFICATION: https://www.rfc-editor.org/errata/eid8352
comparison-op = "==" / "!=" /
"<=" / ">=" /
"<" / ">"
singular-query = rel-singular-query / abs-singular-query
rel-singular-query = current-node-identifier singular-query-segments
abs-singular-query = root-identifier singular-query-segments
singular-query-segments = *(S (name-segment / index-segment))
name-segment = (left-bracket name-selector right-bracket) / ; MODIFICATION: surrogate text rule used
(dot-prefix member-name-shorthand) ; MODIFICATION: surrogate text rule used
index-segment = left-bracket index-selector right-bracket ; MODIFICATION: surrogate text rule used
number = (int / "-0") [ frac ] [ exp ] ; decimal number
frac = "." 1*DIGIT ; decimal fraction
exp = "e" [ "-" / "+" ] 1*DIGIT ; decimal exponent
true = %x74.72.75.65 ; true
false = %x66.61.6c.73.65 ; false
null = %x6e.75.6c.6c ; null
; https://www.rfc-editor.org/rfc/rfc9535#section-2.4
function-name = function-name-first *function-name-char
function-name-first = LCALPHA
function-name-char = function-name-first / "_" / DIGIT
LCALPHA = %x61-7A ; "a".."z"
function-expr = function-name left-paren S [function-argument ; MODIFICATION: surrogate text rule used
*(S comma S function-argument)] S right-paren ; MODIFICATION: surrogate text rule used
function-argument = logical-expr / ; MODIFICATION: https://www.rfc-editor.org/errata/eid8343
filter-query / ; (includes singular-query)
function-expr /
literal
; https://www.rfc-editor.org/rfc/rfc9535#section-2.5
segment = child-segment / descendant-segment
; https://www.rfc-editor.org/rfc/rfc9535#section-2.5.1.1
child-segment = bracketed-selection /
(dot-prefix ; MODIFICATION: surrogate text rule used
(wildcard-selector /
member-name-shorthand))
bracketed-selection = left-bracket S selector *(S comma S selector) S right-bracket
; MODIFICATION: surrogate text rule used
member-name-shorthand = name-first *name-char
name-first = ALPHA /
"_" /
%x80-D7FF /
; skip surrogate code points
%xE000-10FFFF
name-char = name-first / DIGIT
DIGIT = %x30-39 ; 0-9
ALPHA = %x41-5A / %x61-7A ; A-Z / a-z
; https://www.rfc-editor.org/rfc/rfc9535#section-2.5.2.1
descendant-segment = double-dot-prefix (bracketed-selection / ; MODIFICATION: surrogate text rule used
wildcard-selector /
member-name-shorthand)
; https://www.rfc-editor.org/rfc/rfc9535#name-normalized-paths
normalized-path = root-identifier *(normal-index-segment)
normal-index-segment = left-bracket normal-selector right-bracket ; MODIFICATION: surrogate text rule used
normal-selector = normal-name-selector / normal-index-selector
normal-name-selector = squote *normal-single-quoted squote ; 'string', MODIFICATION: surrogate text rule used
normal-single-quoted = normal-unescaped /
ESC normal-escapable
normal-unescaped = ; omit %x0-1F control codes
%x20-26 /
; omit 0x27 '
%x28-5B /
; omit 0x5C \
%x5D-D7FF /
; skip surrogate code points
%xE000-10FFFF
normal-escapable = %x62 / ; b BS backspace U+0008
%x66 / ; f FF form feed U+000C
%x6E / ; n LF line feed U+000A
%x72 / ; r CR carriage return U+000D
%x74 / ; t HT horizontal tab U+0009
"'" / ; ' apostrophe U+0027
"\" / ; \ backslash (reverse solidus) U+005C
(%x75 normal-hexchar)
; certain values u00xx U+00XX
normal-hexchar = "0" "0"
(
("0" %x30-37) / ; "00"-"07"
; omit U+0008-U+000A BS HT LF
("0" %x62) / ; "0b"
; omit U+000C-U+000D FF CR
("0" %x65-66) / ; "0e"-"0f"
("1" normal-HEXDIG)
)
normal-HEXDIG = DIGIT / %x61-66 ; "0"-"9", "a"-"f"
normal-index-selector = "0" / (DIGIT1 *DIGIT)
; non-negative decimal integer
; Surrogate named rules
dot-prefix = "."
double-dot-prefix = ".."
left-bracket = "["
right-bracket = "]"
left-paren = "("
right-paren = ")"
comma = ","
colon = ":"
dquote = %x22 ; "
squote = %x27 ; '
questionmark = "?"
disjunction = "||"
conjunction = "&&"@swaggerexpert/jsonpath is licensed under Apache 2.0 license.
@swaggerexpert/jsonpath comes with an explicit NOTICE file
containing additional legal notices and information.
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