Pause tests in Ember

Simply await on a promise which resolves after a timeout.

test("my test", async function(assert) {
  // setup…
  await new Promise(resolve => setTimeout(resolve, 30000));
  // …assert
});

Repo.count in Ecto

I have often wanted to just do the following but Ecto’s Repo module doesn’t have a count method.

iex> MyApp.Repo.count(MyApp.Account)
42

It is not too difficult to create a count function that will allow you to count the results of any query.

defmodule MyApp.DBUtils do
  import Ecto.Query, only: [from: 2]

  @doc "Generate a select count(id) on any query"
  def count(query),
    do: from t in clean_query_for_count(query), select: count(t.id)

  # Remove the select field from the query if it exists
  defp clean_query_for_count(query),
    do: Ecto.Query.exclude(query, :select)
end

This will provide a shortcut for counting any query

MyApp.DBUtils.count(MyApp.Account) |> Repo.one!

Now, to enable Repo.count we can modify the repo module usually found in lib/my_app/repo.ex

defmodule MyApp.Repo do
  use Ecto.Repo, otp_app: :my_app

  def count(query),
    do: MyApp.DBUtils.count(query) |> __MODULE__.one!
end

That’s it. This will enable a count on any query including complicated queries and those that have a select expression set.

Watch YouTube videos at full window (not full screen)

I use a large 27" iMac which I divide up windows with a browser in the top right of the screen. One thing that often frustrated me is that I could not maximise a video to fill the window completely. I had to fill my entire screen or watch it in the embedded size.

It turns out this is not too hard, change the URL in the browser from https://www.youtube.com/watch?v=oHg5SJYRHA0 to https://www.youtube.com/embed/oHg5SJYRHA0

Tip: View the SQL query behind psql commands

If you want to view the SQL query used to construct the information returned from a psql command (which will help you learn the underlying information schema) then type \set ECHO_HIDDEN

$ psql test
psql (9.4.1)
Type "help" for help.

test=# \set ECHO_HIDDEN
test=# \dt
********* QUERY **********
SELECT n.nspname as "Schema",
  c.relname as "Name",
  CASE c.relkind WHEN 'r' THEN 'table' WHEN 'v' THEN 'view' WHEN 'm' THEN 'materialized view' WHEN 'i' THEN 'index' WHEN 'S' THEN 'sequence' WHEN 's' THEN 'special' WHEN 'f' THEN 'foreign table' END as "Type",
  pg_catalog.pg_get_userbyid(c.relowner) as "Owner"
FROM pg_catalog.pg_class c
     LEFT JOIN pg_catalog.pg_namespace n ON n.oid = c.relnamespace
WHERE c.relkind IN ('r','')
      AND n.nspname <> 'pg_catalog'
      AND n.nspname <> 'information_schema'
      AND n.nspname !~ '^pg_toast'
  AND pg_catalog.pg_table_is_visible(c.oid)
ORDER BY 1,2;
**************************

      List of relations
Schema | Name | Type  | Owner
--------+------+-------+--------
public | temp | table | andrew
(1 row)