jMeta

A JSON mapping utility to help generate meta data of a JSON object. Maps depth and paths to found keys.

Generated paths are compatible with Lodash's _.get and _.set to help manipulate deep data sets.

The generated data is in an accessible Map object which you can run generator functions over as necessary or use the built in keys() and paths() to retrieve information in a more familiar way.

Install

npm install jmeta or yarn add jmeta

Basic Usage

  const JMeta = require('jmeta')
  const _ = require('lodash')

  const data = {
    a: {
      b: {
        c: [
          [ { d: true }, 'ignored', { a: 'duplicate' } ]
        ]
      }
    }
  }
  const jmeta = new JMeta(data)

  console.log(jmeta.paths())     // Outputs: [ 'a', 'a.b.c[0][2].a', 'a.b', 'a.b.c', 'a.b.c[0][0].d' ]
  console.log(jmeta.keys())      // Outputs: [ 'a', 'b', 'c', 'd' ] NOTE: Unique keys
  console.log(jmeta.size)        // Outputs: 5 (NOTE: Accounts for duplicate found keys)
  console.log(jmeta.duplicates)  // Outputs: [ 'a' ]

  let foo = _.get(data, jmeta.paths()[1]) // 'a.b.c[0][2].a'
  console.log(foo)                        // Outputs: 'duplicate'

  // Access the map object directly
  console.log(jmeta.map.get('a')) // Outputs: [ { depth: 1, path: 'a' }, { depth: 6, path: 'a.b.c[0][2].a' } ]

  // You also have the option to get only the "leaves" of the tree. This will return all the final paths and not their connecting branches to them.
  const jmeta = new JMeta(data, { finalPathsOnly: true })

  console.log(jmeta.paths()) // Outputs [ 'a.b.c[0][0].d', 'a.b.c[0][2].a' ]

Paths()

Takes an options object as its only parameter to specify some basic filtering. The options object supports the following filters: { depth: <number>, includes: <string>, key: <string> }. Filtering options can be combined in any way to reduce results accordingly.

NOTE: Paths() will always return an array, on no results found the return will simply be an empty array [].

Filtering Paths

  const JMeta = require('jmeta')
  const _ = require('lodash')

  const data = {
    location: {
      france: [ { name: 'Tom' }, { name: 'Mary' } ],
      italy: [ { name: 'Mike' } ]
    }
  }
  const jmeta = new JMeta(data)

  // DEPTH FILTERING
  console.log(jmeta.paths({ depth: 2 })) // Outputs: ['location.france', 'location.italy']
  console.log(jmeta.paths({ depth: 4 })) // Outputs: ['location.france[0].name', 'location.france[1].name', 'location.italy[0].name']

  // PATH INCLUDES FILTERING
  console.log(jmeta.paths({ includes: 'france' }))    // Outputs: ['location.france', 'location.france[0].name', 'location.france[1].name']
  console.log(jmeta.paths({ includes: 'france[0]' })) // Outputs: ['location.france[0].name']

  // KEY FILTERING
  console.log(jmeta.paths({ key: 'france' })) // Outputs: ['location.france']
  console.log(jmeta.paths({ key: 'name' })  // Outputs: ['location.france[0].name', 'location.france[1].name', 'location.italy[0].name']

Keys()

Takes an options object as its only parameter to specify some basic filtering The options object supports the following filters: { depth: <number> }.

  const JMeta = require('jmeta')
  const _ = require('lodash')

  const data = {
    location: {
      france: [ { person: 'Tom' }, { person: 'Mary' } ],
      italy: [ { person: 'Mike' } ]
    }
  }
  const jmeta = new JMeta(data)

  console.log(jmeta.keys())               // Outputs: [ 'location', 'france', 'person', 'italy' ] NOTE: Returns unique found keys only
  console.log(jmeta.keys({ depth: 2 }))   // Outputs: [ 'france', 'italy' ]
  console.log(jmeta.keys({ depth: 4 }))   // Outputs: [ 'person' ]