Ruby on Rails where query with relations and updated_at compare - ruby-on-rails

Question

I am trying to use where query with relationships and updated_at compare.
When I send this query with updated_at params, I want to fetch only the latest reasons filtered by updated_at date, but it filters with project's updated_at, not by reasons updated_at.
How can I fix this to get reasons data with updated_at filter?
#Getting reasons with updated_at filter
https://server.com/api/v1/entries?updated_at=2016-05-02T01:12:57.204Z
#Model
User
has_many :projects
has_many :reasons, through: :projects
Project
belongs_to :user
has_many :reasons
Reasons
belongs_to :project
#Reasons Controllers
# GET /reasons
def index
reasons = current_user.reasons
updated_at = params[:updated_at]
# Filter with updated_at for reloading from mobile app
if updated_at.present?
# This is my first try, but it shows error because of relations
# reasons = reasons.where("updated_at > ?", DateTime.parse(updated_at))
# This shows reasons data, but it only compares updated_at in Project data, not reasons data...
reasons = reasons.joins(:project).where("projects.updated_at > ?", DateTime.parse(updated_at))
# Get all non deleted objects when logging in from mobile app
else
reasons = reasons.where(deleted: false)
end
render json: reasons
end

Answer 1

You fetching projects.updated_at, but if I understood you right you need to fetch reasons.updated_at
reasons = reasons.joins(:project).where("reasons.updated_at > ?", DateTime.parse(updated_at))
produses that output for me
GET http://localhost:3000/reasons/index?updated_at=2016-05-04T06:43:19.280Z
[
{
"id": 2,
"name": "R2",
"project_id": 3,
"created_at": "2016-05-04T06:43:19.280Z",
"updated_at": "2016-05-04T06:43:19.280Z",
"deleted": false
},
{
"id": 3,
"name": "R3",
"project_id": 3,
"created_at": "2016-05-04T06:43:25.895Z",
"updated_at": "2016-05-04T06:43:25.895Z",
"deleted": false
}
]
And without any filter
GET http://localhost:3000/reasons/index
[
{
"id": 1,
"name": "R1",
"project_id": 3,
"created_at": "2016-05-04T06:43:11.044Z",
"updated_at": "2016-05-04T06:43:11.044Z",
"deleted": false
},
{
"id": 2,
"name": "R2",
"project_id": 3,
"created_at": "2016-05-04T06:43:19.280Z",
"updated_at": "2016-05-04T06:43:19.280Z",
"deleted": false
},
{
"id": 3,
"name": "R3",
"project_id": 3,
"created_at": "2016-05-04T06:43:25.895Z",
"updated_at": "2016-05-04T06:43:25.895Z",
"deleted": false
}
]

Answer 2

It was just changing to reasons.updated_at, thanks!
reasons = reasons.joins(:project).where("reasons.updated_at > ?", DateTime.parse(updated_at))