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json-mask

(★ 870)

Tiny language and engine for selecting specific parts of a JS object, hiding the rest.

파일 탐색기

최종 버전 다운로드 (.zip)

- - node.js.yml
- json-mask.js
- copyright
- jsonMask.js
- jsonMask.min.js
- server.js
- simple_server.js
- compiler.js
- filter.js
- index.js
- util.js
- - index.html
  - jsonMask.html
  - jsonMaskMin.html
  - test.js
- - activities.json
  - invalid.json
- cli-test.js
- compiler-test.js
- filter-test.js
- index-test.js
.gitignore
LICENSE
logo.png
package-lock.json
package.json
README.md

# 설치 가이드

1. 코드 내려받기

git clone https://github.com/nemtsov/json-mask

깃허브에서 프로젝트 코드 전체를 내 컴퓨터로 내려받습니다.

cd json-mask

방금 내려받은 프로젝트 폴더 안으로 이동합니다.

2. Node.js

쉬움 추천

사전 준비물

Git GitHub에서 프로젝트 코드를 내려받으려면 필요합니다.
Node.js npm 명령어를 쓰려면 Node.js가 설치되어 있어야 합니다. LTS(장기지원) 버전을 추천합니다.

npm install

package.json에 명시된 라이브러리들을 내려받아 설치합니다.

npm start

개발/실행 서버를 켭니다.

✅ 명령어 실행 후 터미널에 나타나는 주소(보통 http://localhost:3000 형태)를 브라우저에서 열어보세요.

// repository documentation

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# JSON Mask [![Build Status](https://github.com/nemtsov/json-mask/actions/workflows/node.js.yml/badge.svg)](https://github.com/nemtsov/json-mask/actions/workflows/node.js.yml) [![NPM version](https://img.shields.io/npm/v/json-mask.svg)](https://www.npmjs.com/package/json-mask) [![js-standard-style](https://img.shields.io/badge/code%20style-standard-brightgreen.svg)](http://standardjs.com/)

<img src="https://raw.github.com/nemtsov/json-mask/master/logo.png" align="right" width="267px" />

This is a tiny language and an engine for selecting specific parts of a JS object, hiding/masking the rest.

```js
var mask = require('json-mask');
mask({ p: { a: 1, b: 2 }, z: 1 }, 'p/a,z'); // {p: {a: 1}, z: 1}
```

The main difference between JSONPath / JSONSelect and this engine is that JSON Mask
**preserves the structure of the original input object**.
Instead of returning an array of selected sub-elements (e.g. `[{a: 1}, {z: 1}]` from example above),
it filters-out the parts of the object that you don't need,
keeping the structure unchanged: `{p: {a: 1}, z: 1}`.

This is important because JSON Mask was designed with HTTP resources in mind,
the structure of which I didn't want to change after the unwanted fields
were masked / filtered.

If you've used the Google APIs, and provided a `?fields=` query-string to get a
[Partial Response](https://developers.google.com/gdata/docs/2.0/reference#PartialResponse), you've
already used this language. The desire to have partial responses in
my own Node.js-based HTTP services was the reason I wrote JSON Mask.

_For [express](http://expressjs.com/) users, there's an
[express-partial-response](https://github.com/nemtsov/express-partial-response) middleware.
It will integrate with your existing services with no additional code
if you're using `res.json()` or `res.jsonp()`. And if you're already using [koa](https://github.com/koajs/koa.git)
check out the [koa-json-mask](https://github.com/nemtsov/koa-json-mask) middleware._

This library has no dependencies. It works in Node as well as in the browser.

**Note:** the 1.5KB (gz), or 4KB (uncompressed) browser build is in the `/build` folder.

## Syntax

The syntax is loosely based on XPath:

- `a,b,c` comma-separated list will select multiple fields
- `a/b/c` path will select a field from its parent
- `a(b,c)` sub-selection will select many fields from a parent
- `a/*/c` the star `*` wildcard will select all items in a field

Take a look at `test/index-test.js` for examples of all of these and more.

## Grammar

```
     Props ::= Prop | Prop "," Props
      Prop ::= Object | Array
    Object ::= NAME | NAME "/" Prop
     Array ::= NAME "(" Props ")"
      NAME ::= ? all visible characters except "\" ? | EscapeSeq | Wildcard
  Wildcard ::= "*"
 EscapeSeq ::= "\" ? all visible characters ?
```

## Examples

Identify the fields you want to keep:

```js
var fields = 'url,object(content,attachments/url)';
```

From this sample object:

```js
var originalObj = {
  id: 'z12gtjhq3qn2xxl2o224exwiqruvtda0i',
  url: 'https://plus.google.com/102817283354809142195/posts/F97fqZwJESL',
  object: {
    objectType: 'note',
    content:
      'A picture... of a space ship... launched from earth 40 years ago.',
    attachments: [
      {
        objectType: 'image',
        url: 'http://apod.nasa.gov/apod/ap110908.html',
        image: { height: 284, width: 506 }
      }
    ]
  },
  provider: { title: 'Google+' }
};
```

Here's what you'll get back:

```js
var expectObj = {
  url: 'https://plus.google.com/102817283354809142195/posts/F97fqZwJESL',
  object: {
    content:
      'A picture... of a space ship... launched from earth 40 years ago.',
    attachments: [
      {
        url: 'http://apod.nasa.gov/apod/ap110908.html'
      }
    ]
  }
};
```

Let's test that:

```js
var mask = require('json-mask');
var assert = require('assert');

var maskedObj = mask(originalObj, fields);
assert.deepEqual(maskedObj, expectObj);
```

### Escaping

It is also possible to get keys that contain `,*()/` using `\` (backslash) as escape character.

```json
{
  "metadata": {
    "labels": {
      "app.kubernetes.io/name": "mysql",
      "location": "WH1"
    }
  }
}
```

You can filter out the location property by `metadata(labels(app.kubernetes.io\/name))` mask.

NOTE: In [JavaScript String](https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/String#escape_sequences) you must escape backslash with another backslash:
```js
var fields = 'metadata(labels(app.kubernetes.io\\/name))'
```

### Partial Responses Server Example

Here's an example of using `json-mask` to implement the
[Google API Partial Response](https://developers.google.com/gdata/docs/2.0/reference#PartialResponse)

```js
var http = require('http');
var url = require('url');
var mask = require('json-mask');
var server;

server = http.createServer(function(req, res) {
  var fields = url.parse(req.url, true).query.fields;
  var data = {
    firstName: 'Mohandas',
    lastName: 'Gandhi',
    aliases: [
      {
        firstName: 'Mahatma',
        lastName: 'Gandhi'
      },
      {
        firstName: 'Bapu'
      }
    ]
  };
  res.writeHead(200, { 'Content-Type': 'application/json' });
  res.end(JSON.stringify(mask(data, fields)));
});

server.listen(4000);
```

Let's test it:

```bash
$ curl 'http://localhost:4000'
{"firstName":"Mohandas","lastName":"Gandhi","aliases":[{"firstName":"Mahatma","lastName":"Gandhi"},{"firstName":"Bapu"}]}

$ # Let's just get the first name
$ curl 'http://localhost:4000?fields=lastName'
{"lastName":"Gandhi"}

$ # Now, let's just get the first names directly as well as from aliases
$ curl 'http://localhost:4000?fields=firstName,aliases(firstName)'
{"firstName":"Mohandas","aliases":[{"firstName":"Mahatma"},{"firstName":"Bapu"}]}
```

**Note:** a few more examples are in the `/example` folder.

## Command Line Interface - CLI

When installed globally using `npm i -g json-mask` you can use it like:

`json-mask "<fields>" <input> [<output>]`

### Examples

Stream from online resource:

`curl https://api.myjson.com/bins/krrxw | json-mask "url,object(content,attachments/url)"`

Read from file and write to output file:

`json-mask "url,object(content,attachments/url)" input.json > output.json`

Read from file and print redirect to file:

`json-mask "url,object(content,attachments/url)" input.json > output.json`

## CDN

**unpkg**

- `https://unpkg.com/json-mask/build/jsonMask.js`
- `https://unpkg.com/json-mask/build/jsonMask.min.js`

## License

[MIT](/LICENSE)