Update always sets hstore column

[izoomi]

When I update other fields, the hstore column, is always set as well.

post = Post.create(title: 'Title')
post.update_attribute(:title, 'Title2')
# (0.2ms)  BEGIN
# (0.4ms)  UPDATE "posts" SET "title" = 'Title2', "updated_at" = '2013-05-03 16:01:43.841376', 
# "options" = '' WHERE "posts"."id" = 6100
# (1.6ms)  COMMIT
# => true

The options column gets updated as well.

[diogob]

I'll take a look at this during this week

[sjmadsen]

Rails core is dealing with the flip side of this issue: rails/rails#6127

The problem is that if options already has some stuff in it, and you update a single key within it, you want post.save to update the options column, too.

Rails's change tracking doesn't work at the granularity of keys within a hash, so it's either:

1. hstore columns are always updated or
2. only when the entire attribute is assigned

In the latter case, a partial update won't be saved unless the developer is careful (actually reassigning the attribute or calling #options_will_change! everywhere a partial update occurs).

[edbond]

Even if you don't change anything in hstore column, #save issue UPDATE .....
How to fix the bug?

[staszek-arsdata]

I've ended up with moving hstore column to separate relation. So now if need to access hstore attributes, will call them directly, by product.attrs.data instead of product.attrs.

Before:

class Product
  serialize :attrs, ActiveRecord::Coders::Hstore
end

After:

class Product
  has_one :attrs, class_name: 'ProductAttrs'
end
class ProductAttrs
  belongs_to :product
  serialize :data, ActiveRecord::Coders::Hstore
end

It's not so efficient on selects, but I do many more updates, than selects, so it works for me.

[OctoberComstock]

Has there been any update on this? I've run into an issue where hstore is removing columns in my shared pg database when a different api does an update request. The columns aren't defined in one api but are defined in the other, shouldn't those columns remain concrete and not be removed from the table?