json-query
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    2.2.2 • Public • Published

    json-query

    Retrieves values from JSON objects for data binding. Offers params, nested queries, deep queries, custom reduce/filter functions and simple boolean logic.

    Install via npm

    $ npm install json-query

    API

    var jsonQuery = require('json-query')

    jsonQuery(query, options)

    Specify a query and what to query. Returns an object that describes the result of the query.

     
    var data = {
      people: [
        {name: 'Matt', country: 'NZ'},
        {name: 'Pete', country: 'AU'},
        {name: 'Mikey', country: 'NZ'}
      ]
    }
     
    jsonQuery('people[country=NZ].name', {
      data: data
    }) //=> {value: 'Matt', parents: [...], key: 0} ... etc

    Options:

    • data or rootContext: The main object to query.
    • source or context (optional): The current object we're interested in. Accessed in query with ..
    • parent (optional): An additional context for looking further up the tree. Accessed by ...
    • locals: Specify an object containing helper functions. Accessed by ':filterName'. Expects function(input, args...) with this set to original passed in options.
    • globals: Falls back to globals when no local function found.
    • force (optional): Specify an object to be returned from the query if the query fails. It will be saved into the place the query expected the object to be.
    • allowRegexp (optional): Enable the ~ operator. Before enabling regexp match to anyone, consider the user defined regular expression security concerns.

    Queries

    Queries are strings that describe an object or value to pluck out, or manipulate from the context object. The syntax is a little bit CSS, a little bit JS, but pretty powerful.

    Accessing properties (dot notation)

    person.name

    Array accessors

    people[0]

    Array pluck

    people.name => return all the names of people

    Get all values of a lookup

    lookup[*]

    Array filter

    By default only the first matching item will be returned:

    people[name=Matt]

    But if you add an asterisk (*), all matching items will be returned:

    people[*country=NZ]

    You can use comparative operators:

    people[*rating>=3]

    Or use boolean logic:

    people[* rating >= 3 & starred = true]

    If options.enableRegexp is enabled, you can use the ~ operator to match RegExp:

    people[*name~/^R/i]

    You can also negate any of the above examples by adding a ! before the = or ~:

    people[*country!=NZ]

    Or syntax

    person.greetingName|person.name

    Deep queries

    Search through multiple levels of Objects/Arrays using [**]:

    var data = {
      grouped_people: {
        'friends': [
          {name: 'Steve', country: 'NZ'},
          {name: 'Jane', country: 'US'},
          {name: 'Mike', country: 'AU'},
          {name: 'Mary', country: 'NZ'},
        ],
        'enemies': [
          {name: 'Evil Steve', country: 'AU'}
          {name: 'Betty', country: 'NZ'},
        ]
      }
    }
     
    var result = jsonQuery('grouped_people[**][*country=NZ]', {data: data}).value

    The result will be:

    [
      {name: 'Steve', country: 'NZ'},
      {name: 'Mary', country: 'NZ'},
      {name: 'Betty', country: 'NZ'}
    ]

    Inner queries

    var data = {
      page: {
        id: 'page_1',
        title: 'Test'
      },
      comments_lookup: {
        'page_1': [
          {id: 'comment_1', parent_id: 'page_1', content: "I am a comment"}
        ]
      }
    }
     
    // get the comments that match page's id
    jsonQuery('comments_lookup[{page.id}]', {data: data})

    Local functions (helpers)

    Allows you to hack the query system to do just about anything.

    Some nicely contrived examples:

    var helpers = {
      greetingName: function(input){
        if (input.known_as){
          return input.known_as
        } else {
          return input.name
        }
      },
      and: function(inputA, inputB){
        return inputA && inputB
      },
      text: function(input, text){
        return text
      },
      then: function(input, thenValue, elseValue){
        if (input){
          return thenValue
        } else {
          return elseValue
        }
      }
    }
     
    var data = {
      is_fullscreen: true,
      is_playing: false,
      user: {
        name: "Matthew McKegg",
        known_as: "Matt"
      }
    }
     
    jsonQuery('user:greetingName', {
      data: data, locals: helpers
    }).value //=> "Matt"
     
    jsonQuery(['is_fullscreen:and({is_playing}):then(?, ?)', "Playing big!", "Not so much"], {
      data: data, locals: helpers
    }).value //=> "Not so much"
     
    jsonQuery(':text(This displays text cos we made it so)', {
      locals: helpers
    }).value //=> "This displays text cos we made it so"
     

    Or you could add a select helper:

    jsonQuery('people:select(name, country)', {
      data: data,
      locals: {
        select: function (input) {
          if (Array.isArray(input)) {
            var keys = [].slice.call(arguments, 1)
            return input.map(function (item) {
              return Object.keys(item).reduce(function (result, key) {
                if (~keys.indexOf(key)) {
                  result[key] = item[key]
                }
                return result
              }, {})
            })
          }
        }
      }
    })

    You can also use helper functions inside array filtering:

    jsonQuery('people[*:recentlyUpdated]', {
      data: data,
      locals: {
        recentlyUpdated: function (item) {
          return item.updatedAt < Date.now() - (30 * 24 * 60 * 60 * 1000)
        }
      }
    })

    Context

    Specifying context (data, source, and parent options) is good for databinding and working on a specific object and still keeping the big picture available.

    var data = {
      styles: {
        bold: 'font-weight:strong',
        red: 'color: red'
      },
      paragraphs: [
        {content: "I am a red paragraph", style: 'red'},
        {content: "I am a bold paragraph", style: 'bold'},
      ],
    }
     
    var pageHtml = ''
    data.paragraphs.forEach(function(paragraph){
      var style = jsonQuery('styles[{.style}]', {data: data, source: paragraph}).value
      var content = jsonQuery('.content', data: data, source: paragraph) // pretty pointless :)
      pageHtml += "<p style='" + style "'>" + content + "</p>"
    })

    Query Params

    Params can be specified by passing in an array with the first param the query (with ? params) and subsequent params.

    jsonQuery(['people[country=?]', 'NZ'])

    License

    MIT

    Install

    npm i json-query

    DownloadsWeekly Downloads

    25,042

    Version

    2.2.2

    License

    none

    Last publish

    Collaborators

    • mmckegg