Postgres JSON data type Rails query

Question

I am using Postgres' json data type but want to do a query/ordering with data that is nested within the json.

I want to order or query with .where on the json data type. For example, I want to query for users that have a follower count > 500 or I want to order by follower or following count.

Thanks!

Example:

model User

data: {
     "photos"=>[
       {"type"=>"facebook", "type_id"=>"facebook", "type_name"=>"Facebook", "url"=>"facebook.com"}
      ], 
     "social_profiles"=>[
         {"type"=>"vimeo", "type_id"=>"vimeo", "type_name"=>"Vimeo", "url"=>"http://vimeo.com/", "username"=>"v", "id"=>"1"},
         {"bio"=>"I am not a person, but a series of plants", "followers"=>1500, "following"=>240, "type"=>"twitter", "type_id"=>"twitter", "type_name"=>"Twitter", "url"=>"http://www.twitter.com/", "username"=>"123", "id"=>"123"}
     ]
}

Solution 1

For any who stumbles upon this. I have come up with a list of queries using ActiveRecord and Postgres' JSON data type. Feel free to edit this to make it more clear.

Documentation to the JSON operators used below: https://www.postgresql.org/docs/current/functions-json.html.

# Sort based on the Hstore data:
Post.order("data->'hello' DESC")
=> #<ActiveRecord::Relation [
    #<Post id: 4, data: {"hi"=>"23", "hello"=>"22"}>, 
    #<Post id: 3, data: {"hi"=>"13", "hello"=>"21"}>, 
    #<Post id: 2, data: {"hi"=>"3", "hello"=>"2"}>, 
    #<Post id: 1, data: {"hi"=>"2", "hello"=>"1"}>]> 

# Where inside a JSON object:
Record.where("data ->> 'likelihood' = '0.89'")

# Example json object:
r.column_data
=> {"data1"=>[1, 2, 3], 
    "data2"=>"data2-3", 
    "array"=>[{"hello"=>1}, {"hi"=>2}], 
    "nest"=>{"nest1"=>"yes"}} 

# Nested search:
Record.where("column_data -> 'nest' ->> 'nest1' = 'yes' ")

# Search within array:
Record.where("column_data #>> '{data1,1}' = '2' ")

# Search within a value that's an array:
Record.where("column_data #> '{array,0}' ->> 'hello' = '1' ")
# this only find for one element of the array. 

# All elements:
Record.where("column_data ->> 'array' LIKE '%hello%' ") # bad
Record.where("column_data ->> 'array' LIKE ?", "%hello%") # good

Solution 2

According to this http://edgeguides.rubyonrails.org/active_record_postgresql.html#json there's a difference in using -> and ->>:

# db/migrate/20131220144913_create_events.rb
create_table :events do |t|
  t.json 'payload'
end

# app/models/event.rb
class Event < ActiveRecord::Base
end

# Usage
Event.create(payload: { kind: "user_renamed", change: ["jack", "john"]})

event = Event.first
event.payload # => {"kind"=>"user_renamed", "change"=>["jack", "john"]}

## Query based on JSON document
# The -> operator returns the original JSON type (which might be an object), whereas ->> returns text
Event.where("payload->>'kind' = ?", "user_renamed")

So you should try Record.where("data ->> 'status' = 200 ") or the operator that suits your query (http://www.postgresql.org/docs/current/static/functions-json.html).

Solution 3

Your question doesn't seem to correspond to the data you've shown, but if your table is named users and data is a field in that table with JSON like {count:123}, then the query

SELECT * WHERE data->'count' > 500 FROM users

will work. Take a look at your database schema to make sure you understand the layout and check that the query works before complicating it with Rails conventions.