Rails - Logical Operator on Scopes, is it possible?

Question

I have a class that represents a game (match) with 2 scopes:

  scope :home_lineuped, ->() { includes(:home_lineup).where(home_lineup: {lineuped: true }) }
  scope :away_lineuped, ->() { includes(:away_lineup).where(away_lineup: {lineuped: true }) }

I would like to create a new scope with the logical operator Not And on the results, is it possible?

EDIT: What do I mean?

Imagine that: Match.All gives me matches with ID, 1, 2, 3, 4, 5 and 6;

Match.home_lineuped gives me matches with ID, 1, 2 and 6;

Match.away_lineuped gives me matches with ID 3, 4 and 6;

The result of: (Match.home_lineuped AND Match.away_lineuped) is: 6.

Therefore: Not (Match.home_lineuped AND Match.away_lineuped) will result in matches with ID: 1, 2, 3, 4, and 5.

End EDIT

Best Regards,

David

score 1 · Answer 1 · answered Dec 28 '19 at 23:18

1

Depending on the version of Rails you are using ActiveRecord does have a not method. Hope that helps.

answered Dec 28 '19 at 23:18

John

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I'm on Rails 5.2, could you give me an example? – David Sousa Dec 28 '19 at 23:32
@DavidSousa Beyond the examples from the link? – Dave Newton Dec 29 '19 at 03:29

Thuy Nguyen · Accepted Answer · 2019-12-29T03:32:54.110

1

Your meaning are Match.home_lineuped & Match.away_lineuped and Match.all - (Match.home_lineuped & Match.away_lineuped).

Or create new scope

scope :home_lineuped_and_away_lineuped, ->() { includes(:home_lineup, :away_lineup).where(home_lineups: {lineuped: true }, away_lineups: {lineuped: true }) }

scope :not_home_lineuped_and_away_lineuped, ->() { includes(:home_lineup, :away_lineup).where.not(home_lineups: {lineuped: true }, away_lineups: {lineuped: true }) }

edited Dec 29 '19 at 03:32

answered Dec 29 '19 at 03:25

Thuy Nguyen

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`scope` is just syntactic sugar for declaring class methods. If your method does not fit in a one liner lambda then use normal class method definition for readability. Multi-line scopes are a code smell. – max Jan 01 '20 at 16:55

score 1 · Answer 3 · answered Dec 29 '19 at 10:16

scope :home_lineuped, -> { includes(:home_lineup).where(home_lineup: {lineuped: true }) }
scope :away_lineuped, -> { includes(:away_lineup).where(away_lineup: {lineuped: true }) }

You can call one scope after other for AND logic like this:

Match.home_lineuped.away_lineuped

But if you need scope, you can unite two scopes as:

scope :home_and_lineuped, -> do
  includes(:home_lineup, :away_lineup).
    where(home_lineup: {lineuped: true }, away_lineup: {lineuped: true })
end

And for opposite logic (NOT AND) you can use not:

scope :no_home_away_lineuped, -> do
  includes(:home_lineup, :away_lineup).
    where.not(home_lineup: {lineuped: true }, away_lineup: {lineuped: true })
end

Rails - Logical Operator on Scopes, is it possible?

3 Answers3