Tracking changes on JSONB column

[Edy Laverde]

Tell us about your environment

Ruby Version: 2.6.3p62

Rails Version: 6.0.3

PostgreSQL Version: 11.8

Logidze Version: 1.0.0

What did you do?

Tried to use logidze tracking a JSONB column

I have a table like:

create_table :users do |t|
  t.jsonb :data

  t.timestamps
end

and a trigger (generated by gem) like:

CREATE TRIGGER logidze_on_users
BEFORE UPDATE OR INSERT ON users FOR EACH ROW
WHEN (coalesce(current_setting('logidze.disabled', true), '') <> 'on')
-- Parameters: history_size_limit (integer), timestamp_column (text), filtered_columns (text[]),
-- include_columns (boolean), debounce_time_ms (integer)
EXECUTE PROCEDURE logidze_logger(null, 'updated_at', '{data}', true);

What did you expect to happen?

Store always the changes in the same format

What actually happened?

First change is stored as JSON, but subsequent are Stringify

u = User.create!(data: {hello: 1})
u.update!(data: {hello: 2})
u.update!(data: {hello: 3})
u.reload.log_data =>

 #<Logidze::History:0x00007f956b5d2908 @data={"h"=>[
   {"c"=>{"data"=>{"hello"=>1}}, "v"=>1, "ts"=>1609790311222}, 
   {"c"=>{"data"=>"{\"hello\": 2}"}, "v"=>2, "ts"=>1609790311226}, 
   {"c"=>{"data"=>"{\"hello\": 3}"}, "v"=>3, "ts"=>1609790381173}],
"v"=>3}>

BTW! Thank you for this amazing gem!

[Vladimir Dementyev]

Thanks for the report!

That's what happening here (a note to everyone who would like to pick this issue while I'm enjoying New Year holidays 🎄):

• We use hstore_to_jsonb_loose to efficiently calculate diffs between two JSONB objects—that happens only on UPDATE.
• Initial snapshot doesn't use hstore, thus, we store JSONB as as.

To fix this we need to ensure that snapshots also stringify values.

P.S. @edymerchk except from the format difference, does it cause any issues? I guess, we handle this at the Ruby side correctly, i.e., both strings and Hashes are deserialized into Hashes.