https://github.com/jsonquerylang/jsonquery
A lightweight, flexible, and expandable JSON query language
https://github.com/jsonquerylang/jsonquery
json language query
Last synced: 7 days ago
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A lightweight, flexible, and expandable JSON query language
- Host: GitHub
- URL: https://github.com/jsonquerylang/jsonquery
- Owner: jsonquerylang
- License: other
- Created: 2024-07-19T10:33:06.000Z (9 months ago)
- Default Branch: develop
- Last Pushed: 2025-03-25T11:31:27.000Z (20 days ago)
- Last Synced: 2025-03-31T21:43:41.060Z (14 days ago)
- Topics: json, language, query
- Language: TypeScript
- Homepage: https://jsonquerylang.org/
- Size: 836 KB
- Stars: 214
- Watchers: 2
- Forks: 5
- Open Issues: 6
-
Metadata Files:
- Readme: README.md
- License: LICENSE.md
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README
# JSON Query
A small, flexible, and expandable JSON query language.
Try it out on the online playground:
## Features
- Small: just `3.3 kB` when minified and gzipped! The JSON query engine without parse/stringify is only `1.7 kB`.
- Feature rich (50+ powerful functions and operators)
- Easy to interoperate with thanks to the intermediate JSON format.
- Expressive
- Expandable
## Documentation
On this page:
- [Installation](#installation)
- [Usage](#usage)
- [JavaScript API](#javascript-api)
- [Command line interface (CLI)](#command-line-interface-cli)
- [Development](#development)
- [License](#license)
External pages:
- [JSON Query Documentation](https://jsonquerylang.org/docs/)
- [JSON Query Function reference](https://jsonquerylang.org/reference/)
- [JSON Query Test Suite](test-suite/README.md)
## Installation
Install the JavaScript library via [npm](https://www.npmjs.com/):
```text
npm install @jsonquerylang/jsonquery
```
A Python implementation can be found here: https://github.com/jsonquerylang/jsonquery-python
## Usage
```js
import { jsonquery } from '@jsonquerylang/jsonquery'
const data = {
"friends": [
{ "name": "Chris", "age": 23, "city": "New York" },
{ "name": "Emily", "age": 19, "city": "Atlanta" },
{ "name": "Joe", "age": 32, "city": "New York" },
{ "name": "Kevin", "age": 19, "city": "Atlanta" },
{ "name": "Michelle", "age": 27, "city": "Los Angeles" },
{ "name": "Robert", "age": 45, "city": "Manhattan" },
{ "name": "Sarah", "age": 31, "city": "New York" }
]
}
// Get the array containing the friends from the object, filter the friends that live in New York,
// sort them by age, and pick just the name and age out of the objects.
const output = jsonquery(data, `
.friends
| filter(.city == "New York")
| sort(.age)
| pick(.name, .age)
`)
// output = [
// { "name": "Chris", "age": 23 },
// { "name": "Sarah", "age": 31 },
// { "name": "Joe", "age": 32 }
// ]
// The same query can be written in JSON format instead of the text format.
// Note that the functions `parse` and `stringify` can be used
// to convert from text format to JSON format and vice versa.
jsonquery(data, [
"pipe",
["get", "friends"],
["filter", ["eq", ["get", "city"], "New York"]],
["sort", ["get", "age"]],
["pick", ["get", "name"], ["get", "age"]]
])
```
The build in functions can be extended with custom functions, like `times` in the following example:
```js
import { jsonquery } from '@jsonquerylang/jsonquery'
const options = {
functions: {
times: (value) => (data) => data.map((item) => item * value)
}
}
const data = [1, 2, 3]
const result = jsonquery(data, 'times(3)', options)
// [3, 6, 9]
```
Documentation on the syntax of JSON Query and all supported functions can be found on the website: https://jsonquerylang.org/docs/.
## JavaScript API
The library exports the following functions:
- [`jsonquery`](#jsonquery) is the core function of the library, which parses, compiles, and evaluates a query in one go.
- [`compile`](#compile) to compile and evaluate a query.
- [`parse`](#parse) to parse a query in text format into JSON.
- [`stringify`](#stringify) to convert a query in JSON into the text format.
- [`buildFunction`](#buildfunction) a helper function to create a custom function.
### jsonquery
The function `jsonquery` allows to pass data and a query in one go and parse, compile and execute it:
```text
jsonquery(data: JSON, query: string | JSONQuery, options: JSONQueryOptions) : JSON
```
Here:
- `data` is the JSON document that will be queried, often an array with objects.
- `query` is a JSON document containing a [JSON query](https://jsonquerylang.org/docs/), either the text format or the parsed JSON format.
- `options` is an optional object that can contain the following properties:
- `functions` is an optional map with custom function creators. A function creator has optional arguments as input and must return a function that can be used to process the query data. For example:
```js
const options = {
functions: {
// usage example: 'times(3)'
times: (value) => (data) => data.map((item) => item * value)
}
}
```
If the parameters are not a static value but can be a query themselves, the function `compile` can be used to compile them. For example, the actual implementation of the function `filter` is the following:
```js
const options = {
functions: {
// usage example: 'filter(.age > 20)'
filter: (predicate) => {
const _predicate = compile(predicate)
return (data) => data.filter(_predicate)
}
}
}
```
You can have a look at the source code of the functions in `/src/functions.ts` for more examples.
- `operators` is an optional map with operators, for example `{ eq: '==' }`. The defined operators can be used in a text query. Only operators with both a left and right hand side are supported, like `a == b`. They can only be executed when there is a corresponding function. For example:
```js
import { buildFunction } from 'jsonquery'
const options = {
operators: {
notEqual: '<>'
},
functions: {
notEqual: buildFunction((a, b) => a !== b)
}
}
```
Here an example of using the function `jsonquery`:
```js
import { jsonquery } from '@jsonquerylang/jsonquery'
const data = [
{ "name": "Chris", "age": 23 },
{ "name": "Emily", "age": 19 },
{ "name": "Joe", "age": 32 }
]
const result = jsonquery(data, ["filter", ["gt", ["get", "age"], 20]])
// result = [
// { "name": "Chris", "age": 23 },
// { "name": "Joe", "age": 32 }
// ]
```
### compile
The compile function compiles and executes a query in JSON format. Function `parse` can be used to parse a text query into JSON before passing it to `compile`.
```text
compile(query: JSONQuery, options: JSONQueryOptions) => (data: JSON) => JSON
```
Example:
```js
import { compile } from '@jsonquerylang/jsonquery'
const queryIt = compile(["filter", ["gt", ["get", "age"], 20]])
const data = [
{ "name": "Chris", "age": 23 },
{ "name": "Emily", "age": 19 },
{ "name": "Joe", "age": 32 }
]
const result = queryIt(data)
// result = [
// { "name": "Chris", "age": 23 },
// { "name": "Joe", "age": 32 }
// ]
```
### parse
Function `parse` parses a query in text format into JSON. Function `stringify` can be used to do the opposite.
```text
parse(query: text, options: JSONQueryParseOptions) : JSONQuery
```
Example:
```js
import { parse } from '@jsonquerylang/jsonquery'
const text = 'filter(.age > 20)'
const json = parse(text)
// json = ["filter", ["gt", ["get", "age"], 20]]
```
### stringify
Function `stringify` turns a query in JSON format into the equivalent text format. Function `parse` can be used to parse the text into JSON again.
```text
stringify(query: JSONQuery, options: JSONQueryStringifyOptions) : string
```
Example:
```js
import { stringify } from '@jsonquerylang/jsonquery'
const json = ["filter", ["gt", ["get", "age"], 20]]
const text = stringify(json)
// text = 'filter(.age > 20)'
```
### buildFunction
The function `buildFunction` is a helper function to create a custom function. It can only be used for functions (mostly operators), not for methods that need access the previous data as input.
The query engine passes the raw arguments to all functions, and the functions have to compile the arguments themselves when they are dynamic. For example:
```ts
const options = {
operators: {
notEqual: '<>'
},
functions: {
notEqual: (a: JSONQuery, b: JSONQuery) => {
const aCompiled = compile(a)
const bCompiled = compile(b)
return (data: unknown) => {
const aEvaluated = aCompiled(data)
const bEvaluated = bCompiled(data)
return aEvaluated !== bEvaluated
}
}
}
}
const data = { x: 2, y: 3}
const result = jsonquery(data, '(.x + .y) <> 6', options) // true
```
To automatically compile and evaluate the arguments of the function, the helper function `buildFunction` can be used:
```ts
import { jsonquery, buildFunction } from '@jsonquerylang/jsonquery'
const options = {
operators: {
notEqual: '<>'
},
functions: {
notEqual: buildFunction((a: number, b: number) => a !== b)
}
}
const data = { x: 2, y: 3}
const result = jsonquery(data, '(.x + .y) <> 6', options) // true
```
### error handling
When executing a query throws an error, the library attaches a stack to the error message which can give insight in what went wrong. The stack can be found at the property `error.jsonquery` and has type `Array<{ data: unknown, query: JSONQuery }>`.
```js
const data = {
"participants": [
{ "name": "Chris", "age": 23, "scores": [7.2, 5, 8.0] },
{ "name": "Emily", "age": 19 },
{ "name": "Joe", "age": 32, "scores": [6.1, 8.1] }
]
}
try {
jsonquery(data, [
["get", "participants"],
["map", [["get", "scores"], ["sum"]]]
])
} catch (err) {
console.log(err.jsonquery)
// error stack:
// [
// {
// "data": {
// "participants": [
// { "name": "Chris", "age": 23, "scores": [7.2, 5, 8.0] },
// { "name": "Emily", "age": 19 },
// { "name": "Joe", "age": 32, "scores": [6.1, 8.1] }
// ]
// },
// "query": [
// ["get", "participants"],
// ["map", [["get", "scores"], ["sum"]]]
// ]
// },
// {
// "data": [
// { "name": "Chris", "age": 23, "scores": [7.2, 5, 8.0] },
// { "name": "Emily", "age": 19 },
// { "name": "Joe", "age": 32, "scores": [6.1, 8.1] }
// ],
// "query": ["map", [["get", "scores"], ["sum"]]]
// },
// {
// "data": { "name": "Emily", "age": 19 },
// "query": [["get", "scores"], ["sum"]]
// },
// {
// "data" : undefined,
// "query": ["sum"]
// }
// ]
}
```
## Command line interface (CLI)
When `jsonquery` is installed globally using npm, it can be used on the command line. To install `jsonquery` globally:
```bash
$ npm install -g @jsonquerylang/jsonquery
```
Usage:
```
$ jsonquery [query] {OPTIONS}
```
Options:
```
--input Input file name
--query Query file name
--output Output file name
--format Can be "text" (default) or "json"
--indentation A string containing the desired indentation,
like " " (default) or " " or "\t". An empty
string will create output without indentation.
--overwrite If true, output can overwrite an existing file
--version, -v Show application version
--help, -h Show this message
```
Example usage:
```
$ jsonquery --input users.json 'sort(.age)'
$ jsonquery --input users.json 'filter(.city == "Rotterdam") | sort(.age)'
$ jsonquery --input users.json 'sort(.age)' > output.json
$ jsonquery --input users.json 'sort(.age)' --output output.json
$ jsonquery --input users.json --query query.txt
$ jsonquery --input users.json --query query.json --format json
$ cat users.json | jsonquery 'sort(.age)'
$ cat users.json | jsonquery 'sort(.age)' > output.json
```
## Development
### JavaScript
To develop, check out the JavaScript repo, install dependencies once, and then use the following scripts:
```text
npm run test
npm run test-ci
npm run lint
npm run format
npm run coverage
npm run build
npm run build-and-test
```
Note that a new package is published on [npm](https://www.npmjs.com/package/@jsonquerylang/jsonquery) and [GitHub](https://github.com/jsonquerylang/jsonquery/releases) on changes pushed to the `main` branch. This is done using [`semantic-release`](https://github.com/semantic-release/semantic-release), and we do not use the `version` number in the `package.json` file. A changelog can be found by looking at the [releases on GitHub](https://github.com/jsonquerylang/jsonquery/releases).
## License
Released under the [ISC license](LICENSE.md).