On Wednesday, November 20, 2019 at 1:21:41 PM UTC-8, Mason Kimble wrote:
>
> Basically, can I filter a dataset after it goes to the database?
>
> order_items = OrderItem.dataset.where(order_id: orderId).all (I know this
> would query database)
>
> orders_items_to_match.each { | match_item |
> matching_item = order_items.where(item_id:
> match_item['orderItemId']).first (Does this go back to database or in
> memory)
>
This doesn't work. order_items is an array, not a dataset.
}
>
> 1. Is order_items an array of OrderItem models or a dataset?
>
An array. If you want a dataset, leave off the .all
> 2. If dataset, would .first execute query in memory to match item_id or
> would it go back to the database
>
Datasets always query the Database when asked for results.
> 3. Is there another way to do this? Basically I want to load all the
> Children for a Parent from the database and then filter the Children in
> memory and return a Model if a match is found.
>
You could probably use `order_items.find{|item| ...}` for what you are
describing. This will return the first matching OrderItem if the block
ever returns true, and nil if the block never returns true.
This is kind of a smell though, and should definitely be avoided if
order_items can be a large array. You should see if it is possible to do
the query you want in the database in a single query using a join or
subquery.
Thanks,
Jeremy
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