initial version of ObjectTemplate for easily transforming JSON to JSON

.project

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+<?xml version="1.0" encoding="UTF-8"?>
+<projectDescription>
+	<name>json2json</name>
+	<comment></comment>
+	<projects>
+	</projects>
+	<buildSpec>
+	</buildSpec>
+	<natures>
+	</natures>
+</projectDescription>

LICENSE

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+Copyright 2011 Joel Van Horn. All rights reserved.
+Permission is hereby granted, free of charge, to any person obtaining a copy
+of this software and associated documentation files (the "Software"), to
+deal in the Software without restriction, including without limitation the
+rights to use, copy, modify, merge, publish, distribute, sublicense, and/or
+sell copies of the Software, and to permit persons to whom the Software is
+furnished to do so, subject to the following conditions:
+
+The above copyright notice and this permission notice shall be included in
+all copies or substantial portions of the Software.
+
+THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING
+FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS
+IN THE SOFTWARE. 

README.md

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+This is a little utility that will transform one JSON object structure to another structure defined by a template.
+
+Created by Joel Van Horn. Free to use however you please.

lib/ObjectTemplate.coffee

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+
+sysmo = require 'sysmo'
+
+class ObjectTemplate
+  constructor: (config, parent) ->
+    # if there is no node path, set to current node
+    config.path or= '.'
+    # ensure 'as' template exists
+    config.as or= {}
+    # convert property name to array
+    config.choose = [config.choose] if sysmo.isString config.choose
+
+    @config = config
+    @parent = parent
+
+  transform: (data) =>
+    @data = data;
+    node = @nodeToProcess data
+
+    return data if !node?
+
+    @processProperties node
+
+  processProperties: (node) =>
+    switch sysmo.type node
+      when 'Array' then @processArray node
+      when 'Object' then @processMap node
+      else node
+
+  # assume each array element is a map
+  processArray: (node) =>
+    # convert array to hash
+    if @config.key
+      context = {}
+
+      if @config.deep
+        binder = (element, index) =>
+          key = @chooseKey element
+          value = @processProperties element
+          context[key] = value
+      else
+        binder = (element, index) =>
+          key = @chooseKey element
+          value = @chooseValue(element, {})
+          formatted = @formatNodes node, value, key
+          context[formatted.key] = formatted.value
+    else
+      context = []
+      binder = (element, index) =>
+        value = @chooseValue(element, {})
+        formatted = @formatNodes node, value, index
+        context.push formatted.value
+
+    for element, index in node
+      binder element, index if @config.deep || @chooseNodes node, element, index
+    context
+
+  processMap: (node) =>
+    if @config.nest
+      context = {}
+      # loop through properties to pick up any key/values that should be nested
+      for key, value of node
+        if @chooseNodes node, value, key
+          nested_value = @chooseValue @getNode(node, key), {}
+          formatted = @nestNodes node, nested_value, key
+          context[formatted.key] = formatted.value
+    else
+      value = @chooseValue node, {}
+      context = value
+    context
+
+  nestNodes: (node, value, key) =>
+    return { key: key, value: value } if !sysmo.isFunction @config.nest
+    nested = @config.nest node, value, key
+    nested.key = key if 'key' not of nested
+    nested.value = value if 'value' not of nested
+    nested
+
+  formatNodes: () =>
+    # set default formatter or proxy existing
+    return { key: key, value: value } if !@config.format
+
+    formatted = @config.format node, value, key
+    formatted.key = key if 'key' not of formatted
+    formatted.value = value if 'value' not of formatted
+    formatted
+
+  chooseNodes: (node, value, key) =>
+    # convert array to chooser function that compares key names
+    if !@config.choose
+      return true if @config.all or (@config.key and @config.value)
+      @config.choose = []
+      for key, value of @config.as
+        @config.choose.push value.split('.')[0] if sysmo.isString(value)
+    # create callback for arry
+    if sysmo.isArray @config.choose
+      for element in @config.choose
+        return true if sysmo.isNumber(key) or element is key
+      return false
+    # if not a function yet, treat as boolean value
+    if !sysmo.isFunction @config.choose
+      # if config.key and config.value exist, most likely want to map all
+      choosen = @config.all or (@config.key and @config.value)
+      !!@config.choose #boolean
+    else
+      !!@config.choose node, value, key
+
+  chooseKey: (node) =>
+    # if @config.value exists, use that property of the array element as the value
+    switch sysmo.type @config.key
+      # custom function chooses value based on element
+      when 'Function' then @config.value node
+      # path specifies value from element
+      #when 'String' then @getNode node, @config.key
+      else @getNode node, @config.key
+
+  chooseValue: (node, context) =>
+    # if @config.value exists, use that property of the array element as the value
+    switch sysmo.type @config.value
+      # custom function chooses value based on element
+      when 'Function' then @config.value node
+      # path specifies value from element
+      when 'String' then @getNode node, @config.value
+      # normal mapping ensues
+      else @processTemplate node, context, @config.as
+
+  processTemplate: (node, context, template = {}) =>
+    defaultFilter = (node, value) -> value
+    # loop through properties in template
+    for key, value of template
+      # process mapping instructions
+      switch sysmo.type value
+        # string should be the path to a property on the current node
+        when 'String' then filter = (node, path) => @getNode(node, path) or null
+        # array gets multiple property values
+        when 'Array' then filter = (node, paths) => @getNode(node, path) for path in paths
+        # function is a custom filter for the node
+        when 'Function' then filter = true
+        # object should be { path: 'path.to.node', defaultValue: ... }
+        # when 'Object' then filter = (node, value) -> @getNode(node, value.path) or value.defaultValue
+        when 'Object' then filter = (node, config) => new @constructor(config, @).transform node
+        else filter = defaultFilter
+
+      # if the template specifies a function, pass node and key, otherwise it's an internal filter
+      value = if filter is true then filter node, key else filter node, value
+      # format key and value
+      formatted = @config@formatNodes node, value, key
+      context[formatted.key] = formatted.value
+
+    if !@config.nest
+      # loop through properties iode to pick up any key/values that should be choose
+      for key, value of node
+        # skip if node property already used, the property was specified by the template, or it should not be choose
+        if @paths(node).indexOf(key) is -1 and key not in context and @chooseNodes node, value, key
+          formatted = @formatNodes node, value, key
+          context[formatted.key] = formatted.value
+
+    context
+
+  nodeToProcess: (node) =>
+    @getNode node, @config.path
+
+  getNode: (node, path) =>
+    return node if path is '.'
+    @paths node, path
+    sysmo.getDeepValue node, path
+
+  # track the first property in a path for each node through object tree
+  paths: (node, path) =>
+    path = path.split('.')[0] if path
+
+    if !@pathCache
+      @pathNodes = if @parent then @parent.pathNodes else (@pathNodes = [])
+      @pathCache = if @parent then @parent.pathCache else (@pathCache = [])
+
+    index = @pathNodes.indexOf node
+
+    if !path
+      return if index isnt -1 then @pathCache[index] else []
+
+    if index is -1
+      paths = []
+      @pathNodes.push node
+      @pathCache.push paths
+    else
+      paths = @pathCache[index]
+
+    paths.push(path) if path and paths.indexOf(path) == -1
+    paths
+
+
+# register module
+module.exports = ObjectTemplate

lib/json2json.coffee

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+
+exports.ObjectTemplate = require './ObjectTemplate'

package.json

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+{ "name" : "json2json"
+, "description" : "A simple way to transform a JSON object to another JSON structure"
+, "version" : "0.0.1"
+, "author" : "Joel Van Horn <[email protected]>"
+, "repository" :
+  { "type" : "git"
+  , "url" : "git://github.com/joelvh/json2json.git"
+  }
+, "bugs" : { "web" : "https://github.com/joelvh/json2json/issues" }
+, "os" : [ "linux", "darwin", "freebsd" ]
+, "directories" : { "lib" : "./lib/" }
+, "main" : "./lib/json2json"
+, "dependencies" :
+  { "sysmo" : "https://github.com/joelvh/Sysmo.js/tarball/master"
+  }
+, "engines" : { "node" : ">=0.1.97" }
+, "licenses" :
+  [ { "type" : "MIT"
+    , "url" : "http://github.com/joelvh/json2json/raw/master/LICENSE"
+    }
+  ]
+}