Ecto/Elixir, How can I query by date? - datetime

Question

I am working on statistics page of my app and trying to query data by date.
To get the date range, I use Calendar.Date
date_range = Date.days_after_until(start_date, end_date, true)
|> Enum.to_list
And it returns date list of dates and each date looks like "2017-04-07". So with the date I got from date_range, I tried to query but it triggers an error like below.
where cannot be cast to type Ecto.DateTime in query: from o in Myapp.Order,
where: o.created_date >= ^~D[2017-04-07]
For created_date field of Order, I made field like this,
field :created_date, Ecto.DateTime.
If I want to query by date, how can I query it?
Thank in advance.

Answer 1

It looks like you're trying to compare a date and datetime. You need to cast one of them to the other type so the comparison works, e.g. convert the datetime in the database to a date:
date = ~D[2017-01-01]
from p in Post, where: fragment("?::date", p.inserted_at) >= ^date
or convert the Elixir Date to NaiveDateTime:
{:ok, datetime} = NaiveDateTime.new(date, ~T[00:00:00])
from p in Post, where: p.inserted_at >= ^datetime
If you have a start and end date, you just need to add an and to either. You don't need to generate the whole list of dates using any library.
from p in Post,
where: fragment("?::date", p.inserted_at) >= ^start_date and
fragment("?::date", p.inserted_at) <= ^end_date
or
from p in Post,
where: p.inserted_at >= ^start_datetime and
p.inserted_at <= ^end_datetime