The `/directory_items` route needs to have a .json url, but the rails
url helper `_path` doesn't return the format of the route.
I tried passing in a format options to `directory_items_path`. Which
works in the rails console
```
[8] pry(main)> directory_items_path(params.merge(:format => :json))
=> "/directory_items.json?page=1"
```
but when I added that some logic to the controller it comes out as
```
/directory_items?format=json&page=1
```
(which is actually how I expect it to work based on how you pass in the
format param). Anyways, because I couldn't figure out how to pass a
format to the `_path` helper I just used URI.parse to append `.json`
manually.
Doing .pluck(:column).first is a very common pattern in Discourse and in
most cases, a limit cause isn't being added. Instead of adding a limit
clause to all these callsites, this commit adds two new methods to
ActiveRecord::Relation:
pluck_first, equivalent to limit(1).pluck(*columns).first
and pluck_first! which, like other finder methods, raises an exception
when no record is found
This reduces chances of errors where consumers of strings mutate inputs
and reduces memory usage of the app.
Test suite passes now, but there may be some stuff left, so we will run
a few sites on a branch prior to merging
- Move user directory from `/directory` to `/users/`
- Defaults to 'weekly' time period
- Don't include deleted topics/posts in the results
- Move heart icon to header instead of on each row
- "Users" instead of "Users found"
