Prototyping a simple json+hal client

.gitignore

node_modules

hal-sugar.js

var Promise = require('bluebird');
var halfred = require('halfred');
var parseTemplate = require('uri-template').parse;
var request = Promise.promisify(require('request'));

halfred.enableValidation();

function Builder(parent) {
  this.parent = parent;
  this.rels = [];
}

Builder.fake = false;

Builder.fakeResponses = {
  "http://api.io/": {
    _links: {"ea:orders": {href: "http://api.io/orders"}}
  },
  "http://api.io/orders": {
    _links: {"ea:find": {href: "http://api.io/orders/{id}", templated: true}}
  },
  "http://api.io/orders/13": {
    _links: {
      "ea:customer": {href: "http://api.io/customer/42"},
      "ea:basket": {href: "http://api.io/basket/123"}
    }
  },
  "http://api.io/customer/42": {
    name: 'customer 42'
  },
  "http://api.io/basket/123": {
    name: 'basket 123'
  }
}

Builder.prototype.href = function (url) {
  this.rels.push({href: url});

  return new Builder(this);
}

Builder.prototype.follow = function (rel, params) {
  this.rels.push({rel: rel, params: params || {}});

  return new Builder(this);
}

Builder.prototype.dump = function () {
  if (this.parent) {
    this.parent.dump();
  }

  console.log(JSON.stringify(this, null, ' '));
}

Builder.prototype.get = function () {
  var self = this;

  function fetchRels() {
    return Promise.all(
      self.rels.map(self._fetchRelation.bind(self))
    ).then(function () {
      return self._merge();
    });
  }

  if (self.parent) {
    return self.parent.get().then(fetchRels);
  } else {
    return fetchRels();
  }
}

Builder.prototype._fetchRelation = function (rel) {
  var href;

  if (rel.rel) {
    var link;

    this.parent.rels.some(function (r) {
      // TODO: handle array relations
      link = r.resource.link(rel.rel);
      return link;
    })

    if (!link) {
      throw new Error(
        "no link relation for " + rel.rel + " in " + JSON.stringify(this.parent.rels));
    }

    if (link.templated) {
      href = parseTemplate(link.href).expand(rel.params);
    } else {
      href = link.href;
    }
  } else if (rel.href) {
    var href = rel.href;
  }

  return this._fetch(href).then(function (resource) {
    rel.resource = resource;
  });

}

Builder.prototype._merge = function (childData) {
  var resp = {};

  this.rels.forEach(function (rel) {
    if (rel.rel) {
      resp[rel.rel] = rel.resource.original();
    }
  });

  if (childData) {
    Object.keys(childData).forEach(function (key) {
      resp[key] = childData[key];
    })
  };

  if (this.parent) {
    resp = this.parent._merge(resp);
  }

  return resp;
}

Builder.prototype._fetch = function (url) {
  console.log("fetching url", url);

  if (Builder.fake) {
    return Promise.resolve(halfred.parse(Builder.fakeResponses[url]));
  } else {
    return request({
      method: 'GET',
      url: url,
      headers: {
        'User-Agent': 'hal-sugar @ https://gist.github.com/9f55538c019824bfd9aa',
        'Accept': 'application/hal+json'
      }
    }).spread(function (response, body) {
      // TODO: error handling
      console.log("got response", response.statusCode);
      return halfred.parse(JSON.parse(body));
    });
  }
}

var api;

if (Builder.fake) {
  api = new Builder().href('http://api.io/')

  var order = api.follow("ea:orders").follow("ea:find", {id: 13})

  order.follow('ea:basket')
  order.follow('ea:customer')

  order.get().then(function (res) {
    console.log(JSON.stringify(res, null, '  '));
  })
} else {
  api = new Builder().href('http://www.holderdeord.no/api/')

  var representative = api.follow('representatives').follow('find', {slug: 'es'});
  representative.follow('party')
  representative.follow('committees')

  representative.get().then(function (res) {
    console.log(JSON.stringify(Object.keys(res), null, '  '));
  });
}

package.json

{
  "dependencies": {
    "request": "~2.36.0",
    "bluebird": "~1.2.4",
    "halfred": "~0.2.0",
    "uri-template": "~0.4.1"
  }
}