Rails timestamp search using datetime_field_tag

I recently worked on an issue when creating a Rails form to search and display objects by timestamp and spent far too much time troubleshooting an issue with the datetime_field_tag form helper.

The issue began with the following two lines in my view:

    <%= datetime_field_tag(:begin_timestamp, params[:begin_timestamp]) %>
    <%= datetime_field_tag(:end_timestamp,   params[:end_timestamp]) %>

Evidently, you cannot place more than one space between the name assigned to the form helper and the value to populate in the form helper. The above two lines don’t format well in this wordpress blog post, but there are 3 spaces between ‘:end_timestamp’ and ‘params[:end_timestamp]’. The parameter was passed to the controller, and the code worked, but it would not display the current selection in the datetime_field_tag on submit.

The fix was to remove the additional formatting spaces, ie:

    <%= datetime_field_tag(:begin_timestamp, params[:begin_timestamp]) %>
    <%= datetime_field_tag(:end_timestamp, params[:end_timestamp]) %>

Hope this helps somebody. I spent far too much time on this.

More info:

> rails server
=> Booting Puma
=> Rails 5.2.3 application starting in production
=> Run `rails server -h` for more startup options
Puma starting in single mode...
* Version 3.12.1 (ruby 2.6.0-p0), codename: Llamas in Pajamas
* Min threads: 5, max threads: 5
* Environment: production
* Listening on tcp://0.0.0.0:3000
Use Ctrl-C to stop