CODEWITHSUNDEEP
ruby-on-railsactiverecord
Jason Swett
Jason Swett

Reputation: 45104

to_sql doesn't work when pluck is involved

When I to to_sql on the following query it works fine:

2.1.8 :017 > Task.joins(:recurrence).group('recurrences.id').to_sql
 => "SELECT `tasks`.* FROM `tasks` INNER JOIN `recurrences` ON `recurrences`.`id` = `tasks`.`recurrence_id` GROUP BY recurrences.id"

But then when I add pluck it doesn't work:

2.1.8 :018 > Task.joins(:recurrence).group('recurrences.id').pluck('tasks.title').to_sql
   (21.0ms)  SELECT tasks.title FROM `tasks` INNER JOIN `recurrences` ON `recurrences`.`id` = `tasks`.`recurrence_id` GROUP BY recurrences.id
NoMethodError: undefined method `to_sql' for #<Array:0x007fbde9863f18>

Apparently the addition of pluck changes the type of object from ActiveRecord_Relation to Array, and you obviously can't perform to_sql on an array.

What I'm wanting it to output (for starters) is this:

SELECT tasks.title FROM `tasks` INNER JOIN `recurrences` ON `recurrences`.`id` = `tasks`.`recurrence_id` GROUP BY recurrences.id

...which is in fact what I copy/pasted from the query generated by Task.joins(:recurrence).group('recurrences.id').pluck('tasks.title') without the to_sql.

Is it possible to do what I'm wanting to do?

Upvotes: 6

Views: 1683

Answers (1)

Jason Swett
Jason Swett

Reputation: 45104

I figured it out. I have to use select.

> Task.select('tasks.title').joins(:recurrence).group('recurrences.id').to_sql
 => "SELECT tasks.title FROM `tasks` INNER JOIN `recurrences` ON `recurrences`.`id` = `tasks`.`recurrence_id` GROUP BY recurrences.id"

Upvotes: 6

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