Rails 4 / postgresql 9.4 - Query and update a ruby object inside an array

Question

I have a method (find_by_sql) that outputs a ruby object inside an array like this:

[#<deal id: 66480, opportunity_id: 4, admin_user_id: 1, created_at: "2015-09-20 18:37:29", updated_at: "2015-09-20 18:37:29", deal_available: true>]

How can I update the object's 'deal_available' attribute inside my database in raw postgresql ?

I tried different ways to write it but I stumble on the fact that it's very specific: it's an array, and inside there is a ruby object and I must manage to tell postgresql to change the value of deal_available: true to deal_available: false.

In local, I tried: logger.debug "Here is the resulting object for update:

 #{@deal_question[0]}

but I get:

#<@deal_question:0x007fd9b3963270>

Here is how @deal_question is created

@deal_question = Deal.find_by_sql(
      " SELECT \"deals\".*
        FROM \"deals\"
        WHERE (opportunity_id = #{@deal.id}
        AND deal_available = true)
        ORDER BY \"deals\".\"id\" ASC LIMIT 1"
    )

I don't even have a postgresql query to suggest here because first I need to understand how to query this ruby object inside the array.

Why don't you use ActiveRecord instead of writing raw SQL ?

Caillou
– Caillou

2015-10-13 16:14:17 +00:00
Commented Oct 13, 2015 at 16:14 — Caillou
– Caillou, Commented Oct 13, 2015 at 16:14

K M Rakibul Islam · Accepted Answer · 2015-10-14 03:50:44Z

1

You actually don't need a raw SQL query to update the deal_available attribute of your @deal_question object.

You can use update_attributes to achieve that.

# assuming @deal_question is an array
@deal_question[0].update_attributes(deal_available: false)

If you really want to use raw sql to update the attribute, then do this way:

array = [#<deal id: 66480, opportunity_id: 4, admin_user_id: 1, created_at: "2015-09-20 18:37:29", updated_at: "2015-09-20 18:37:29", deal_available: true>]
# grab the object to be updated
@deal_question = array[0]
# build the sql query string
sql = "UPDATE deals SET deal_available = false WHERE opportunity_id = #{@deal_question.id}"
# execute the sql to update the object
ActiveRecord::Base.connection.execute(sql)

edited Oct 14, 2015 at 3:50

answered Oct 14, 2015 at 3:16

K M Rakibul Islam

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1 Comment

Mathieu Over a year ago

thanks, first suggestion did not work because it's only updating the objetc@deal question while I want to update the database. your second suggestion works. thanks!

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