Ndtyjky

I have an ActiveRecord model (using STI) MonetaryChange::PaymentPromise that has subtotal_cents as an attribute / column (an integer).

My controller is updating that model/attribute, but for some reason, I'm getting the old/original value when I call map and the updated (correct) value when I call pluck. For example:

V410MonetaryChange::PaymentPromise.where(id: 1).pluck(:subtotal_cents)

=> [24600] # this is the correct updated value



V410MonetaryChange::PaymentPromise.where(id: 1).map(&:subtotal_cents)

=> [12300] # this is the original value, but it should have been updated to 24600

I notice that the SQL that Rails generates for the pluck method is much simpler:

(0.5ms)  SELECT "v410_monetary_changes"."subtotal_cents" 

FROM "v410_monetary_changes" 

WHERE "v410_monetary_changes"."type" IN ('V410MonetaryChange::PaymentPromise') 

AND "v410_monetary_changes"."deleted_at" IS NULL 

AND "v410_monetary_changes"."id" = $1  [["id", 1]]

but the SQL for the map method loads a whole bunch of associations after the first query:

  V410MonetaryChange::PaymentPromise Load (0.6ms)  SELECT "v410_monetary_changes".* FROM "v410_monetary_changes" WHERE "v410_monetary_changes"."type" IN ('V410MonetaryChange::PaymentPromise') AND "v410_monetary_changes"."deleted_at" IS NULL AND "v410_monetary_changes"."id" = $1  [["id", 1]]

  V410OrderedSku Load (0.3ms)  SELECT  "v410_ordered_skus".* FROM "v410_ordered_skus" WHERE "v410_ordered_skus"."deleted_at" IS NULL AND "v410_ordered_skus"."id" = $1 LIMIT 1  [["id", 1]]

  V410OrderedSkusV410Sku Load (0.2ms)  SELECT  "v410_ordered_skus_v410_skus".* FROM "v410_ordered_skus_v410_skus" WHERE "v410_ordered_skus_v410_skus"."v410_ordered_sku_id" = $1 LIMIT 1  [["v410_ordered_sku_id", 1]]

  V410Sku Load (0.2ms)  SELECT  "v410_skus".* FROM "v410_skus" WHERE "v410_skus"."id" = $1 LIMIT 1  [["id", 1]]

Any idea why this is the case, and how I can resolve this?

I tried adding .reload to my query, but the results were the same:

V410MonetaryChange::PaymentPromise.where(id: 1).reload.map(&:subtotal_cents)

=> [12300]

Edit 1:
I can confirm that the database has the correct value (24600). When I open a psql console, and run the query:

SELECT "v410_monetary_changes"."subtotal_cents" 

    FROM "v410_monetary_changes" 

    WHERE "v410_monetary_changes"."type" IN ('V410MonetaryChange::PaymentPromise') 

    AND "v410_monetary_changes"."deleted_at" IS NULL 

    AND "v410_monetary_changes"."id" = 1;

I get:

 subtotal_cents 

----------------

          24600

(1 row)

So Rails must be doing something with the associations that is causing it to give me an old version of the record. Any ideas why?

OK, important Rails lesson learned today!

I recently added an after_initialize callback to this model, which set the default values (including subtotal_cents) for newly initialized records.

What I didn't realise is that this callback was re-initializing (ie overwriting in memory after load) existing records with the default values.

My fix was to change

after_initialize :set_default_currency_amounts

to

after_initialize :set_default_currency_amounts, unless: Proc.new { |pp| pp.persisted? }

In my case, this is why the SQL was so long - my defaults required the loading of some associated models to get the default value for subtotal_cents. This was the clue that helped me solve this.

Thank you to everyone for your help!