from data-nugget to data-scalars

data-nugget_to_data-scalars.js

// from data-nugget to data-scalars,
// a first end to end look at the problem by example

const Immutable = require('immutable');

// let's define some record structure to represent simple type schemas.
// we need some composite types…
let ListType = Immutable.Record({type:'List', kind:'Collection', fields: Immutable.Map()}, 'ListType');
let MapType = Immutable.Record({type:'Map', kind:'Collection', fields: Immutable.Map()}, 'MapType');

// … and some scalars
let PercentType = Immutable.Record({type:'Percent', kind:'Scalar'}, 'PercentType');
let StringType = Immutable.Record({type:'string', kind:'Scalar'}, 'StringType');


// next we define a sample data-nugget.
// i.e some data, and a schema representing its type structure
let dataNugget = Immutable.Map({
  data: Immutable.Map({
    description: "some text",
    percents: Immutable.List([0, 0.2, 0.5])
  }),

  schema: new MapType({fields: Immutable.Map({
    "description": new StringType(),
    "percents": new ListType({fields: Immutable.Map({"0": new PercentType()})})
  })})
});

// implementation detail ignore this
// intersperses value in array
// given array ['foo', 'bar'] and value 'inserted' return ['foo', 'inserted, 'bar']
let intersperse = (array, value) => array.reduce((result, current, index) =>{
  let next = index == array.length - 1 ? current : [current].concat(value);
  return result.concat(next); 
}, []);

// provide a mecanism to mine a nugget so as to produce a smaller data-nugget/egg (data+schema)
//
// given a data-nugget and a path returns a subfield of the data-egg/nugget.
// the path represents the path from the root of the nugget's value to the subfield.
// path can be string or [string]
let extractEggFromNugget = (nugget, path) => {
  let dataPath = ['data'].concat(path);
  let schemaPath = ['schema'].concat(path);
  schemaPath = intersperse(schemaPath, 'fields');

  return Immutable.Map({
    data: nugget.getIn(dataPath),
    schema: nugget.getIn(schemaPath)
  });
};


// let's extract some eggs to be fed to data-scalar polymer elements
let descriptionEgg = extractEggFromNugget(dataNugget, 'description');
let firstPercentEgg = extractEggFromNugget(dataNugget, ['percents', '0']);

console.log(descriptionEgg);
// Map { "data": "some text", "schema": StringType { type: "string", kind: "Scalar" } }

console.log(firstPercentEgg);
// Map { "data": 0, "schema": PercentType { type: "Percent", kind: "Scalar" } }


// finally in some polymer element
// <data-scalars data-egg={{descriptionEgg}}></data-scalars>
// <data-scalars data-egg={{firstPercentEgg}}></data-scalars>