Scope 'near' does not work with pluck()

[santuxus]

Hello!

I needed to get array of only one column values from my locations table and it seems that pluck() always returns location.id, not depending what attribute is passed to the function.

Location.near('Lille')
=>
Location id: 4, area: "Lille", lat: 50.6292, lon: 3.05726, created_at: "2012-01-25 18:13:09",
Location id: 6, area: "Villeneuve-d'Ascq", lat: 50.6233, lon: 3.145, created_at: "2012-01-25 19:05:44"

Location.near('Lille').pluck(:id)
=> [4, 6]

Location.near('Lille').pluck(:created_at)
=> [4, 6]

Regards,
Santuxus

[alexreisner]

This is going to be difficult to fix since pluck and near both modify the SELECT clause.

[rweng]

can we detect that pluck is called and throw an exception? This could save some debugging time :(

[alexreisner]

That would be difficult as well. I just added a section to the README which explains why pluck doesn't work. Hopefully that will save others some time.

[rweng]

Just an idea you've probably already considered: Is it possible to do the custom selects in a subselect?

[alexreisner]

I don't see how you could use a subquery (assuming that's what you mean by subselect) to fix this issue.

[danielpclark]

You can use pluck if you option away order.

Address.near("New York, NY 10001", 300, {order: ""}).pluck(:addressable_id)

The SQL generated doesn't permit (some) things to be chained onto after the ORDER BY query is added. So just pass an options hash with an empty string for order and it removes that query part and your free to add more chainable commands.

I've tested pluck with many different column names and they all work.

Using Ruby 2.2.1, Rails 4.1.10, and geocoder 1.2.7

UPDATE

Looking at the SQL query there seems to be quite a difference. https://gist.github.com/danielpclark/7efbf51cf6d3e710564e

So it looks like pluck chops off the first half of the query... I don't believe that that is the desired result.

[DavidBennettPIO]

Thanks @danielpclark you just saved 2000+ ms off my load time!

I think the first half of the query was for generating the distance for ordering but seeing as you removed the order anyway it doesn’t seem to matter if the select gets eaten by pluck.

This is the code I'm using now an it seems to work:

address_ids = Address.near([lat, lng], 30, :units => :km, order: '').ids

Which gives me the SQL:

SELECT "addresses"."id" FROM "addresses"  WHERE (addresses.latitude BETWEEN -35.152174481775624 AND -34.61258151822438 AND addresses.longitude BETWEEN 138.30770837845907 AND 138.96548562154092 AND (6371.0 * 2 * ASIN(SQRT(POWER(SIN((-34.882378 - addresses.latitude) * PI() / 180 / 2), 2) + COS(-34.882378 * PI() / 180) * COS(addresses.latitude * PI() / 180) * POWER(SIN((138.636597 - addresses.longitude) * PI() / 180 / 2), 2)))) BETWEEN 0.0 AND 30)

[danielpclark]

Thanks for letting me know. Now I plan on using it. 👍

[ajmiciano]

Thanks @danielpclark!

[derekprior]

Slightly different, way of doing the above in case you are composing things in way that doesn't let you easily change the call to near:

Address.near([lat, lng], 30).reorder('').pluck(:id)