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Creating Source Adapters

Once RhoConnect is installed we’re ready to build a RhoConnect source adapter to integrate with our backend application. To define a RhoConnect source you just need to identify a handful of operations to interact with your backend data source: login, query, sync, create, update, delete and logoff. If you generated a JavaScript RhoConnect application then you will need to generate JavaScript Source adapters. Likewise, if you generated a Ruby RhoConnect application, you will need to generate Ruby Source Adapters.

To demonstrate how this works we have setup a dummy backend for a Product model. This backend will allow you to perform all CRUD operations, however the data will be reset every hour.

Let’s go ahead and create a source adapter for this model.

 rhoconnect source product --js
 rhoconnect source product
You can also accomplish this from RhoStudio as explained in the Ruby Source Adapter guide

Now let’s replace the contents of the Source Adapter generated code. Normally, you will replace each method with code specific to your backend.

var rc = require('rhoconnect_helpers');
var http = require('http');
var host = 'rhostore.herokuapp.com';

var Product = function(){

  this.login = function(resp){
    resp.send(true);
  };

  this.query = function(resp){
    var result = {};
    var str = '';

    http.request('http://' + host + '/products.json', function(res){
      res.on('data', function(chunk){
        str += chunk;
      });
      res.on('end', function(){
        var data = JSON.parse(str);
        for(var i in data){
          var item = data[i];
          result[item.product.id.toString()] = item.product;
        }
        resp.send(result);
      });
    }).end();
  };

  this.create = function(resp){
    var postData = JSON.stringify({ 'product': resp.params.create_object });
    var str = '';
    var options = {
      host: host,
      path: '/products.json',
      method: 'POST',
      headers: { 
        'Content-Type': 'application/json', 
        'Content-Length': postData.length
      }
    };
    var req = http.request(options, function(res){
      res.on('data', function(chunk){
        str += chunk;
      });
      res.on('end', function(){
        var data = JSON.parse(str);
        resp.send(data.product.id.toString());
      });
    });
    req.write(postData);
    req.end();
  };

  this.update = function(resp){
    var objId = resp.params.update_object.id;
    var putData = JSON.stringify({ "product": resp.params.update_object });
    // Remove the id from the hash, we don't need it.
    delete putData.id;
    var options = {
      host: host,
      path: '/products/' + objId + '.json',
      method: 'PUT',
      headers: { 
        'Content-Type': 'application/json',
        'Content-Length': putData.length
      }
    };
    var req = http.request(options, function(res){
      res.on('data', function(){});
      res.on('end', function(){
        resp.send(true);
      });
      res.on('error', function(){
        resp.send(false);
      });
    });
    req.write(putData);
    req.end();
  };

  this.del = function(resp){
    var objId = resp.params.delete_object.id;
    var options = {
      host: host,
      path: '/products/' + objId + '.json',
      method: 'DELETE',
      headers: { 'Content-Type': 'application/json' }
    };
    var req = http.request(options, function(res){
      res.on('data', function(){});
      res.on('end', function(){
        resp.send(true);
      });
      res.on('error', function(){
        resp.send(false);
      });
    });
    req.end();
  };

  this.logoff = function(resp){
    resp.send(true);
  };

  this.storeBlob = function(resp){
    // TODO: Handle post requests for blobs here.
    // Reference the blob object's path with resp.params.path.
    new rc.Exception(
      resp, "Please provide some code to handle blobs if you are using them."
    );
  };
};

module.exports = new Product();       
      
 
require 'json'
require 'rest_client'

class Product < Rhoconnect::Model::Base

  def initialize(source)
    @base = 'http://rhostore.herokuapp.com/products'
    super(source)
  end

  def query(params=nil)
    rest_result = RestClient.get("#{@base}.json").body

  if rest_result.code != 200
    raise Rhoconnect::Model::Exception.new("Error connecting!")
  end
    parsed = JSON.parse(rest_result)

    @result={}
    parsed.each do |item|
      @result[item["product"]["id"].to_s] = item["product"]
    end if parsed
  end

  def create(create_hash)
    res = RestClient.post(@base,:product => create_hash)

    # After create we are redirected to the new record.
    # We need to get the id of that record and return
  # it as part of create so rhoconnect can establish a link
  # from its temporary object on the client to this newly
  # created object on the server
    JSON.parse(
    RestClient.get("#{res.headers[:location]}.json").body
  )["product"]["id"]
  end

  def update(update_hash)
    obj_id = update_hash['id']
    update_hash.delete('id')
    RestClient.put("#{@base}/#{obj_id}",:product => update_hash)
  end

  def delete(delete_hash)
    RestClient.delete("#{@base}/#{delete_hash['id']}")
  end
end

The above example will work with our test backend, if you are attempting to connect to your own backend data, you should read more about Source Adapters and the corresponding methods: