How to save a hash or json string into a jsonb field

Question

I have a json string from my active admin from "{\"en\":\"Lorem\"}"

I want to save this in my question.name field, which is of postgres jsonb type.

class Question < ActiveRecord::Base
  serialize :name
end

# db/schema.rb
create_table "preset_questions", force: :cascade do |t|
  t.jsonb    "name",               default: {}
end

I've tried the following:

question.update(name:"{\"en\":\"Lorem\"}")
question.update(name:JSON.parse("{\"en\":\"Lorem\"}"))

Result for both:

question.name
=> nil

Let check any error in your console when doing this? 2 your commands should work fine! — Hieu Pham
– Hieu Pham, Commented Feb 12, 2016 at 10:45

Martin Verdejo · Accepted Answer · 2016-02-12 15:03:05Z

8

Got it to work by removing serialize :name. Looks like rails already knows what to do given that the column type is jsonb

class Question < ActiveRecord::Base
end

# db/schema.rb
create_table "preset_questions", force: :cascade do |t|
  t.jsonb    "name",               default: {} 
end

question.update(name:"{\"en\":\"Lorem\"}")
question.update(name:JSON.parse("{\"en\":\"Lorem\"}"))

Both return

question.name
=> {"en"=>"lorem", "id"=>"ipsum"}

answered Feb 12, 2016 at 15:03

Martin Verdejo

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3 Comments

medBouzid Over a year ago

am Using Rails 5.1.4 and seems that saving a json string in a JSONB field will save it as string and not as a hash

medBouzid Over a year ago

from what I found this is the new behavior starting from v5.0.0 here is the source github.com/rails/rails/commit

buncis Over a year ago

@medBouzid I think that bug is already fixed in newest rails

Caillou · Accepted Answer · 2016-02-12 10:41:51Z

1

In Rails, you can specify in your ActiveRecord Model that it must serialize a column before saving it, and unserialize it after reading it. It makes you able to save any structure in a string column of your database.

class Question < ActiveRecord::Base
   serialize :name
end

Then you can save your hash just like this :

question.update(name: {en: "Lorem"} }

Documentation : http://api.rubyonrails.org/classes/ActiveRecord/AttributeMethods/Serialization/ClassMethods.html

answered Feb 12, 2016 at 10:41

Caillou

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1 Comment

Caillou Over a year ago

Well, it's just that you must have a string column in the database, and that you must give the hash itself as an argument of update, not an already serialized verison of it.

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