Get array of attribute values, along with an attribute from a join

Question

I've gotten close, I believe. My current query is this

items = Item.select("items.icon, items.name, item_types.name AS type, items.level, items.rarity, items.vendor_value")
.joins(:item_type)
.where("item_types.name = '#{params[:item_type]}'")

This gets me an array of Item objects that at least respond to :type with the item_type.name.

What I am looking for is an array of arrays that look so:

[icon, name, item_type.name, level, rarity, vendor_value]

I've already had it working fairly easily, but it is important to me that this be done in one fell swoop via sql, instead of creating a map afterwards, because there are times where I need to respond with 40k+ items and need this to be as fast as possible.

Not sure how to go from the above to an array of attributes, without performing a map.

Thanks for your help!

Wally Altman · Accepted Answer · 2015-06-06 04:51:23Z

3

The pluck method does precisely what you want. In your case, it would look like this:

items = Item.joins(:item_type)
            .where("item_types.name = ?", params[:item_type])
            .pluck("items.icon", "items.name", "item_types.name AS type",
                   "items.level", "items.rarity", "items.vendor_value")

I also changed the where call to use parameterization instead of string interpolation—interpolation isn't recommended, especially when you're getting a value from the user.

1 Comment

Borromakot Over a year ago

Thanks! I've used pluck, but not with multiple values before. I didn't know it could do that. Very useful.

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