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Active Record: How to select rows based on the number of items in an array column (PostgreSQL)

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•1 min read
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Lucian Ghinda
Part of seriesRuby/Rails Tips and TILs

Context

You have a column in your table that is used as an array , like this: 

 t.string 'ids', array: true

And you want to select all records that have more than N elements in the array

Solution

In PostgreSQL, you can use cardinality to achieve this:

Model.where("cardinality(ids) > 5")
#ruby#ruby-on-rails#postgresql#sql#coding

Ruby/Rails Tips and TILs

Part 7 of 8

Short Ruby or Ruby on Rails tips or Today I Learned moments

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All about code - Ruby and Rails technical content written by Lucian Ghinda

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I write here quick thoughts, ideas, tips, and learnings about programming, programmers, and building software. Most of my focus is on Ruby, Rails, Hotwire, and everything about web applications.