CODEWITHSUNDEEP
ruby-on-railsrubyruby-on-rails-4
Megamind
Megamind

Reputation: 111

Implementation of conditional where clauses using Arel table

I have the following keystring, where column 1 represents the Value, Column 2 is the score, column 3 is the keystring. Column 2 is calculated by checking the column1-value in keystring.

If column-1 value is 7, then it is less than 25. So, Column 2 value will be 0.

enter image description here

To implement this, I made upper_limit and lower_limit. 

Lower_Limit | Upper Limit
NULL        | 25
25          | 75
75          | 125
125         | 250
250         | 500
500         | NULL

Am using the following Query:

score_line_item = Model.where("upper_limit > ? AND lower_limit <= ?", value, value)
score_line_item = Model.where("upper_limit IS null AND lower_limit >= ? ", value) unless score_line_item.present?
score_line_item = Model.where("lower_limit IS null AND upper_limit > ? ", value) unless score_line_item.present?

How do I implement the same using Rails Way ? (May be in 1 line). I am unable to remove the repetitive lines. I am looking for a better solution for the above question even if it is with Arel table.

Upvotes: 0

Views: 283

Answers (1)

James Daniels
James Daniels

Reputation: 6981

Just combine with SQL or

score_line_item = Model.where(
                    "upper_limit > :value AND lower_limit <= :value OR upper_limit IS null AND lower_limit >= :value OR lower_limit IS null AND upper_limit > :value ", 
                    {value: value}
                  )

Also does this need to be SQL? Couldn't you just do it in Ruby?

# Usage: credit_scoring(35) #=> 1
def credit_scoring(value)
  [25, 75, 125, 250, 500].count do |lower_bound| 
     lower_bound <= value
  end
end

Upvotes: 1

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