sc-simple-ds.js

DS = SC.Namespace.create();

DS.property = function(transforms) {
  return SC.computed(function(key, value) {
    var data = get(this, 'data'), value, val,
        name = transforms.keyName || key;
    var from = transforms && transforms.from;
    var to   = transforms && transforms.to;

    // if the data hasn't been populated yet, return immediately
    if (!data) { return; }

    if (value !== undefined) {
      val = to ? to(value) : value;
      SC.set(data, name, val);
    } else {
      value = SC.get(data, name);
      if (from) { value = from(value); }
    }

    return value;
  }).property('data')
};

DS.property.string = DS.property;

DS.property.integer = function(keyName) {
  return DS.property({
    keyName: keyName,
    from: function(serialized) {
      return Number(serialized);
    },
    to: function(deserialized) {
      return String(deserialized);
    }
  });
};

DS.property.date = function(keyName) {
  return DS.property({
    keyName: keyName,
    from: function(raw) {
      return new Date(raw);
    },
    to: function(date) {
      return JSON.stringify(date);
    }
  })
};

DS.hasMany = function(other, klass) {
  return function() {
    var keys = SC.get(this.get('data'), other);

    if (keys) {
      var recordArray = SC.ArrayProxy.create(), content = [];

      keys.forEach(function(key) {
        content.push(klass.load(key));
      })

      recordArray.set('content', content);
      return recordArray;
    } else {
      return;
    }
  }.property('data.' + other + '.@each').cacheable()
};

DS.RecordArray = SC.Object.extend(SC.Array, {
  keys: null,
  objectAt: function(idx) {
    var keys = this.get('keys'),
        klass = this.get('klass');

    if (!keys) { return; }

    var id = keys.objectAt(idx);

    return klass.loadRecord(id);
  }
});

DS.Record = SC.Object.extend({
  unknownProperty: function(key, value) {
    var data = this.get('data');

    if (value !== undefined) {
      SC.set(data, key, value);
    } else {
      value = SC.get(data, key);
    }

    return value;
  },

  save: function() {
    DS.saveRecord(this);
  }
});

DS.RECORDS = {};

DS.recordHashFor = function(klass, id) {
  var recordsHash = DS.RECORDS[SC.guidFor(klass)];
  if (!recordsHash) { DS.RECORDS[SC.guidFor(klass)] = {} }

  return recordsHash[id];

};

DS.setRecordHash = function(klass, id, hash) {
  var recordsHash = DS.RECORDS[SC.guidFor(klass)];
  if (!recordsHash) { DS.RECORDS[SC.guidFor(klass)] = {}; recordsHash = {} }

  recordsHash[id] = hash;
};

// default method to look up a record by class and id.
// a record class can define its own load method for special behavior
//
// you can override this method to change the global loading behavior
DS.loadRecord = function(klass, id, force) {
  var url = klass['instanceUrl'].fmt(id),
      resource = klass['resource'],
      instance = klass.create();

  if (!force) {
    var recordHash = DS.recordHashFor(klass, id);
    if (recordHash) { return instance.set('data', recordHash); } 
  }

  $.ajax({
    url: url,
    dataType: 'json',
    success: function(json) {
      DS.setRecordHash(klass, id, json[resource]);
      instance.set('data', json[resource]);
    }
  });

  return instance;
};

// params can be a Hash or a URL-encoded String
DS.loadRecords = function(klass, params) {
  var url = klass['collectionUrl'],
      resource = klass['resource'],
      recordArray = SC.ArrayProxy.create();

  $.ajax({
    url: url,
    data: params,
    dataType: 'json',
    success: function(json) {
      var rawArray = json[resource], array = [];

      rawArray.forEach(function(item) {
        DS.setRecordHash(klass, item.id, item);
        array.push(klass.create({ data: item }));
      });

      recordArray.set('content', array);
    }
  });

  // Return the recordArray right away. It will asynchronously
  // be populated with data when the data comes in via Ajax
  return recordArray;
}

DS.saveRecord = function(record) {
  var url = SC.get(this.constructor, 'instanceUrl');
  url = url.fmt(this.get('id'));

  // TODO: Something on success vs. failure
  $.ajax({
    type: 'PUT',
    url: url,
    data: SC.get(this, 'data'),
    dataType: 'json',
  });
}

DS.Record.reopenClass({
  // force forces the record to be loaded even if it's already
  // been fetched
  load: function(id, force) {
    return DS.loadRecord(this, id, force);
  },

  // fetches all records. You can specify params as a Hash or
  // URL-encoded string to narrow down the results. Returned
  // records will override existing records
  //
  // TODO: Make sure instantiated objects get the updated
  // data hashes.
  loadAll: function(params) {
    return DS.loadRecords(this, params);
  }
});

/**
  USAGE

// TODO: Convention over configuration for instance URL, resource
// name and class URL
Person = DS.Record.extend({
  firstName: DS.property.string(),
  lastName: DS.property.string(),

  fullName: function() {
    return this.get('firstName') + ' ' + this.get('lastName');
  }.property('firstName', 'lastName')
});

Person.reopenClass({
  collectionUrl: "/people",
  instanceUrl: "/people/%@",
  resource: "people"
});

var person = Person.load(1);

var people = Person.loadAll(); // can use this wherever an
                               // Array is expected, like in
                               // an ArrayController

*/

Totally understood, and thanks for posting this!

I'm mostly thinking out loud here so we can collectively converge. @staugaard and @shajith have been working on a similar library today and will be stealing the best ideas from here. @wycats and I have planned to reconvene later this week to polish and release.

Some updates & fixes by the above-mentioned @staugaard and @shajith are available here: https://gist.github.com/1167122