Ember insert record with multiple relationships - not working - ember.js

Question

I've been stuck on this problem for two days now, and have not been able to find a solution online. I am hoping some of you might be able to help.
I've got the following models:
App.Project = DS.Model.extend({
name: DS.attr('string'),
project_teams: DS.hasMany('projectTeam')
});
App.ProjectTeam = DS.Model.extend({
sde_effort: DS.attr('number'),
project: DS.belongsTo('project'),
team: DS.belongsTo('team')
});
App.Team = DS.Model.extend({
project_teams: DS.hasMany('projectTeam'),
name: DS.attr('string')
});
And the following code in my projectsController:
var project = store.createRecord('project', {
name: projectName
});
project.save().then(function(projectRecord){
var teamHookerUpper = function(teamId, sdeEffort, idx){
store.find('team', teamId).then(function(team){
var project_team = store.createRecord('project_team', {
project: projectRecord,
sde_effort: sdeEffort,
team: team
});
console.log('project team has been created');
project_team.save().then(function(pt){
projectTeamIds.push(pt.get('id'));
if(idx == sdeHeads.length - 1){
console.log(projectRecord);
projectRecord.set('project_teams', projectTeamIds);
projectRecord.save();
}
});
});
}
for(var i = 0; i < sdeHeads.length; i++){
teamHookerUpper(teamIds[i], sdeHeads[i], i);
}
});
The logic is the following:
Get the value from a txt in the front end and create a new Project. When you create the project, select all teamIds and sdeEfforts (a metadata value) associated with that project, create multiple TeamProject objects and link them to the newly created Project. The Team value associated with ProjectTeam is just an id and I am able to retrieve the object by making a call to the DB.
At present the Project object is created successfully, and multiple ProjectTeam objects are created successfully, however when adding the ProjectTeams, the values for project and team are null. Furthermore, you see that each ProjectTeam object i create a push to an array. Once i've iterated over all teamIds (from the front end), i add the array of ProjectTeams to Project and update Project.
However, when inspecting the ajax call, I see that a PUT request is sent to the appropriate url however, no data is sent whatsoever (status code 204)
I have been stuck on this for two days and have exhausted all the resources I managed to find. I am hoping the community will be able to assist me with this one.
Is there another approach of going about this? Have I been fixated into this approach that I haven't considered other approaches? Please give me some guidance, that would be highly appreciated.
EDIT:-----
here are ajax calls and their respective responses:
{"project":{"name":"fghfg"}} <- post Project
{"project_teams":[],"project":{"id":3,"name":"fghfg", "created_at":"2014-01-03T12:11:28.372Z","updated_at":"2014-01-03T12:11:28.372Z","project_teams":[]}} <- response
{"project_team":{"sde_effort":34,"project":"3","team":"1"}} <- post ProjectTeam
{"projects":[],"teams":[],"project_team":{"id":2,"sde_effort":34,"created_at":"2014-01-03T12:11:28.494Z","updated_at":"2014-01-03T12:11:28.494Z","project":null,"team":null}} <- response
{"project_teams":[],"team":{"id":1,"name":"Team 1","created_at":"2014-01-03T12:10:42.787Z","updated_at":"2014-01-03T12:10:42.787Z","project_teams":[]}} <- response for GET teams/1
{"project":{"name":"fghfg"}} <- PUT project. No response for this call :/
EDIT 2:
Here's the corresponding data schema in ruby
ActiveRecord::Schema.define(version: 20131230144053) do
create_table "project_teams", force: true do |t|
t.integer "sde_effort"
t.integer "project_id"
t.integer "team_id"
t.datetime "created_at"
t.datetime "updated_at"
end
add_index "project_teams", ["project_id"], name: "index_project_teams_on_project_id"
add_index "project_teams", ["team_id"], name: "index_project_teams_on_team_id"
create_table "projects", force: true do |t|
t.string "name", null: false
t.datetime "created_at"
t.datetime "updated_at"
end
create_table "teams", force: true do |t|
t.string "name", null: false
t.datetime "created_at"
t.datetime "updated_at"
end
end