Ruby on Rails Love-In

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raej: Sep 25, 2003; "Being drunk is the worst feeling of all. Except for all those other feelings."

I have a list of beers that a user has in their cellar through cellared_beers so that a user has many beers through cellared_beers and vice versa. Each cellared_beer has extra data like year and size attached.

I am wanting to display the tallied results of the cellared_beers for a user on a page. Right now I have the following code which will get the counts:

code:

beer_groups = @user.cellared_beers.count(:group => [:beer_id,:year,:size])

which produces results like:

code:

=> {[1, 2008, "12oz"]=>1, [1, 2009, "12oz"]=>3, [1, 2010, "12oz"]=>1}

How do I map it out so that I can show the beer attributes based on beer_id, the year, size, and amount?

Something like:
Foo Beer(beer.name), Bar Brewery(beer.brewery.name),2008,12oz,1
Foo Beer(beer.name), Bar Brewery(beer.brewery.name),2009,12oz,3
Foo Beer(beer.name), Bar Brewery(beer.brewery.name),2010,12oz,1

EDIT:
Doing this in my controller:

code:

@beer_counts = beer_groups.each.map do |values,count|
"#{values[0]},#{values[1]},#{values[2]},#{count}"
end

spits out a nice array that I'm looking for:

code:

=> ["1,2008,12oz,1", "1,2009,12oz,3", "1,2010,12oz,1"]

For my view, how would I go about going through each in the @beer_counts array and use the first value to pull out a beer object?

Something like:

code:

@beer_counts.each do |values|
beer = Beer.find(values[0])
end

and be able to format the beer attributes(beer.name, beer.brewery.name, etc), as well as the cellared_beer attributes (year, size) in a view?

raej fucked around with this message at 21:39 on May 8, 2013

# ? May 8, 2013 18:48

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# ? May 15, 2024 10:39

UxP: Aug 27, 2007

DreadCthulhu posted:

So by default the cookies are signed and basically given full trust regarding whether the user is who he claims he is? Permissions in there as well?

Yes. Signing them isn't a magic solution, but it prevents anyone from actually tampering with a cookie to change their user_id or role, or whatever you happen to store in a cookie, as long as no one knows what your session secret is ( 'config/initializers/secret_token.rb' ), as long as OpenSSL's HMAC remains trusted.

# ? May 8, 2013 23:10

DreadCthulhu: Sep 17, 2008; What the fuck is up, Denny's?!

UxP posted:

Yes. Signing them isn't a magic solution, but it prevents anyone from actually tampering with a cookie to change their user_id or role, or whatever you happen to store in a cookie, as long as no one knows what your session secret is ( 'config/initializers/secret_token.rb' ), as long as OpenSSL's HMAC remains trusted.

Fair enough. I remember reading that the rationale is that if someone steals your secret token straight off your production box, you're probably screwed enough that the cookie is the last of your problems. As in, they likely have full access to the DB at that point, which is a lot more interesting.

If I'm understanding this correctly, the advantage of the signed cookie approach is that you don't have to have a server-side map of permissions/sessions, and you can effectively "distribute" the burden onto the clients? Keeping a properly synced user/permissions/sessions map in memory at all times and persisting it to db seems like extra work. I think some people use solutions like Redis for that as well.

# ? May 9, 2013 00:05

raej: Sep 25, 2003; "Being drunk is the worst feeling of all. Except for all those other feelings."

Is there a way to break up a hash into an array? That should solve my previous problem.

controller

code:

beer_groups = @user.cellared_beers.count(:group => [:beer_id,:year,:size])
@beer_counts = beer_groups.each.map do |values,count|
      beer = Beer.find(values[0])
      "#{beer.id},#{beer.name},#{beer.brewery.id},#{beer.brewery.name},#{beer.style},#{beer.abv},#{values[1]},#{values[2]},#{count}"
    end

this spits out a single line for @beer_counts that looks like

code:

1,Test beer,1,Test Brewery 1,0,3.2,2008,12oz,1

So that if I do an .each do in my view, and pass in an array value, the return is a character of that string, not the value between the commas.

Is there a way to spit it out so that I can call beer[1] and get "Test beer" instead of ","?

# ? May 15, 2013 20:07

Lexicon: Jul 29, 2003; I had a beer with Stephen Harper once and now I like him.

raej posted:

Is there a way to break up a hash into an array? That should solve my previous problem.

code:

>> { :abc => 1, :def => 2 }.to_a
=> [[:abc, 1], [:def, 2]]

# ? May 15, 2013 20:18

raej: Sep 25, 2003; "Being drunk is the worst feeling of all. Except for all those other feelings."

Lexicon posted:

code:

>> { :abc => 1, :def => 2 }.to_a
=> [[:abc, 1], [:def, 2]]

Hmm, maybe what I have ins't a hash at all then? When I'm assembling the data in the controller, I need it to be broken up instead of one big string. Any ideas?

# ? May 15, 2013 20:33

manero: Jan 30, 2006

raej posted:

Is there a way to break up a hash into an array? That should solve my previous problem.

controller
code:
beer_groups = @user.cellared_beers.count(:group => [:beer_id,:year,:size])
@beer_counts = beer_groups.each.map do |values,count|
 ...

The .each.map looks suspect. Just use map? I don't see why you'd want to chain .each.map like that.

# ? May 15, 2013 20:43

Smol: Jun 1, 2011; Stat rosa pristina nomine, nomina nuda tenemus.

Are you trying to output CSV?

# ? May 15, 2013 20:44

raej: Sep 25, 2003; "Being drunk is the worst feeling of all. Except for all those other feelings."

manero posted:

The .each.map looks suspect. Just use map? I don't see why you'd want to chain .each.map like that.

Changing it to just .map still spits out a big string

Smol posted:

Are you trying to output CSV?

I'm not trying to output csv. Ideally in my view I would call up each value to the view fir display purposes so that

code:

1,Test beer,1,Test Brewery 1,0,3.2,2008,12oz,1

translates to beer_id, beer_name, brewery_id, brewery_name, style, abv, year, size

# ? May 15, 2013 20:51

Smol: Jun 1, 2011; Stat rosa pristina nomine, nomina nuda tenemus.

Ok, I think I understand your problem now. Does this do what you're looking for?

code:

beer_groups = @user.cellared_beers.count(:group => [:beer_id,:year,:size])
@beer_counts = 
  beer_groups.map do |values,count|
    beer = Beer.find(values[0])
    [beer.id, beer.name, beer.brewery.id, beer.brewery.name, beer.style, beer.abv, values[1], values[2], count]
  end

Smol fucked around with this message at 21:23 on May 15, 2013

# ? May 15, 2013 21:02

raej: Sep 25, 2003; "Being drunk is the worst feeling of all. Except for all those other feelings."

Smol posted:

Ok, I think I understand your problem now. Does this do what you're looking for?

code:

beer_groups = @user.cellared_beers.count(:group => [:beer_id,:year,:size])
@beer_counts = 
  beer_groups.map do |values,count|
    beer = Beer.find(values[0])
    [beer.id, beer.name, beer.brewery.id, beer.brewery.name, beer.style, beer.abv, values[1], values[2], count]
  end

Woo! Yes, that's exactly what I was looking for! Thank you!

# ? May 15, 2013 21:40

Pardot: Jul 25, 2001

Isn't that going to do n+1 queries where n is how many beers they have?

Honestly, I'd just write a single raw sql query and skip active record entirely at this point. However I've been working on a postgres service for a few years now, so I might be crazy.

# ? May 16, 2013 04:05

prom candy: Dec 16, 2005; Only I may dance

What is it that you're actually trying to do? Can you give me an example of the input that you've got and the output that you desire? Because yes, that's going to do n+1 queries and get awful slow.

# ? May 16, 2013 04:41

raej: Sep 25, 2003; "Being drunk is the worst feeling of all. Except for all those other feelings."

prom candy posted:

What is it that you're actually trying to do? Can you give me an example of the input that you've got and the output that you desire? Because yes, that's going to do n+1 queries and get awful slow.

Models are Users, Beers, Breweries, and Cellared_beers.

Breweries have many beers.
Users have many beers through cellared_beers.

The Beer model contains information on a kind of beer (Name, brewery, description, ABV, style, etc)
A Cellared_beer represents a physical bottle one owns and the attributes. (Size, year, etc)

A user can go to a beer page and "add to cellar" which asks for year and size of the beer to be added. This creates a cellared_beer with user_id, beer_id, year, size.

A user can go to his cellar and list all of the cellared_beers, but grouped by similar size and dates.

Output would look like:

code:

Name      | Brewery   | ABV  | Style       | Size | Year | Amount
Bud Light | Budweiser | 4.2% | Light Lager | 12oz | 2013 | 18
Bud Light | Budweiser | 4.2% | Light Lager | 22oz | 2013 | 3
Bud Light | Budweiser | 4.2% | Light Lager | 12oz | 2012 | 6

# ? May 16, 2013 17:45

Pardot: Jul 25, 2001

Ruby code:

ActiveRecord::Base.connection.raw_connection.exec(<<-SQL, [user_id])
select
  beers.name as name
, breweries.name as brewery
, beer.abv
, beer.style
, cellard_beers.size
, cellard_beers.year
, count(*) as amount
from cellard_beers
join beers on beers.id = cellard_beers.beer_id
join breweries on breweries.id = beers.breweries_id
where 
  cellard_beers.user_id = $1
group by 1,2,3,4,5,6
order by 7 desc
SQL

# ? May 16, 2013 18:01

A MIRACLE: Sep 17, 2007; All right. It's Saturday night; I have no date, a two-liter bottle of Shasta and my all-Rush mix-tape... Let's rock.

Pardot posted:

Ruby code:

Cool, I've never seen this before. Thanks!

# ? May 16, 2013 18:56

prom candy: Dec 16, 2005; Only I may dance

Pardot is obviously the master but I'd like to try my hand at writing that with AR:

code:

CellaredBeer.
  select('beers.name, breweries.name, beers.abv, beers.style, cellared_beers.size, cellared_beers.year, count(*) as amount').
  includes({:beer => :brewery}).
  where('cellared_beers.user_id = ?', current_user.id).
  group('1,2,3,4,5,6').
  order('amount DESC')

Is that about right? I like to avoid writing raw SQL where I can.

# ? May 17, 2013 00:42

manero: Jan 30, 2006

prom candy posted:

Pardot is obviously the master but I'd like to try my hand at writing that with AR:
code:
CellaredBeer.
  select('beers.name, breweries.name, beers.abv, beers.style, cellared_beers.size, cellared_beers.year, count(*) as amount').
  includes({:beer => :brewery}).
  where('cellared_beers.user_id = ?', current_user.id).
  group('1,2,3,4,5,6').
  order('amount DESC')
Is that about right? I like to avoid writing raw SQL where I can.

Wrap it all up in a class method!

# ? May 17, 2013 03:46

Cocoa Crispies: Jul 20, 2001; Vehicular Manslaughter!; Pillbug

DreadCthulhu posted:

If I'm understanding this correctly, the advantage of the signed cookie approach is that you don't have to have a server-side map of permissions/sessions, and you can effectively "distribute" the burden onto the clients? Keeping a properly synced user/permissions/sessions map in memory at all times and persisting it to db seems like extra work. I think some people use solutions like Redis for that as well.

HMAC is secure when you pick a quality secret. Rack's cookie session implementation that Rails uses SHA-1, which while it's too weak for passwords, are fine for data that isn't a human-generated (i.e. bad) password.

My understanding is that the cookie is just identity, and authorization for actions based on that identity lives in the app at runtime.

Syncing a user/session map between memory and database isn't hard, but expiring it can be, and if your app lives in multiple datacenters, that adds a whole new dimension of "fun" to database synchronization.

# ? May 17, 2013 16:43

Lexicon: Jul 29, 2003; I had a beer with Stephen Harper once and now I like him.

In ruby, is there an easy way to tell at the point of execution whether "self" refers to a class or an instance? I'm debugging some meta-programming hell (that I didn't write) and self.extend is getting called on a class instead of an instance somehow, and causing class-wide definitions that I don't want to exist. Basically, I want the opportunity to insert in "debugger if self is a class" so I can see where it's being called from. Any thoughts?

# ? May 20, 2013 17:43

Obsurveyor: Jan 10, 2003

Lexicon posted:

In ruby, is there an easy way to tell at the point of execution whether "self" refers to a class or an instance? I'm debugging some meta-programming hell (that I didn't write) and self.extend is getting called on a class instead of an instance somehow, and causing class-wide definitions that I don't want to exist. Basically, I want the opportunity to insert in "debugger if self is a class" so I can see where it's being called from. Any thoughts?

Doesn't the class method tell you want you need to know?

code:

self.class == Class

# ? May 20, 2013 18:57

plasticbugs: Dec 13, 2006; Special Batman and Robin

I know this is a really stupid question, but what the heck.

I'm working with push notifications in my iOS app. Each notification needs its own unique identifier. The notifications are very ephemeral. They're created and pushed to a remote server (Urban Airship) from my Rails server in one step, so I don't need to store a notification object on my Rails server. I just need to assign the notifications a unique ID when they're created just before they're pushed.

My thought was to just create a Notification model and give it no attributes. Then, every time the Rails app creates a new notification to push, it will also create and save a new Notification instance, which will auto-increment its id and assign the object's id to the notification's unique identifier (UA calls these aliases).

This sounds like a dumb way to create a counter. If my app is successful, it's going to fill my database with tens of thousands of empty records over the lifetime of the app.

Is there a cleaner, more pragmatic way to create a counter like this that also avoids race conditions?

# ? May 21, 2013 06:51

The Journey Fraternity: Nov 25, 2003; I found this on the ground!

plasticbugs posted:

I know this is a really stupid question, but what the heck.

I'm working with push notifications in my iOS app. Each notification needs its own unique identifier. The notifications are very ephemeral. They're created and pushed to a remote server (Urban Airship) from my Rails server in one step, so I don't need to store a notification object on my Rails server. I just need to assign the notifications a unique ID when they're created just before they're pushed.

My thought was to just create a Notification model and give it no attributes. Then, every time the Rails app creates a new notification to push, it will also create and save a new Notification instance, which will auto-increment its id and assign the object's id to the notification's unique identifier (UA calls these aliases).

This sounds like a dumb way to create a counter. If my app is successful, it's going to fill my database with tens of thousands of empty records over the lifetime of the app.

Is there a cleaner, more pragmatic way to create a counter like this that also avoids race conditions?

https://rubygems.org/gems/uuid

# ? May 21, 2013 07:31

Pardot: Jul 25, 2001

Yeah I'd go the UUID route if you can. If you reallllllly need incrementing ones you can just create a raw sequence. http://www.postgresql.org/docs/9.2/static/functions-sequence.html

code:

will=# create sequence heysup;
CREATE SEQUENCE
Time: 17.725 ms
will=# select nextval(heysup);
ERROR:  column "heysup" does not exist
LINE 1: select nextval(heysup);
                       ^
Time: 2.227 ms
will=# select nextval('heysup');
 nextval
---------
       1
(1 row)

Time: 3.958 ms
will=# select nextval('heysup');
 nextval
---------
       2
(1 row)

Time: 0.241 ms
will=# select nextval('heysup');
 nextval
---------
       3
(1 row)

You don't need an external gem though for ruby UUID generation:

Ruby code:

~ $ ruby -r securerandom -e 'p SecureRandom.uuid'
"cb7f89a5-e698-471a-8a4a-6ac007c7a66a"
~$ ruby -r securerandom -e 'p SecureRandom.uuid'
"538d3b76-c55a-41b9-9ce6-4c268e5b983e"

Pardot fucked around with this message at 07:36 on May 21, 2013

# ? May 21, 2013 07:33

plasticbugs: Dec 13, 2006; Special Batman and Robin

The Journey Fraternity posted:

https://rubygems.org/gems/uuid

Pardot posted:

Yeah I'd go the UUID route if you can.
...
You don't need an external gem though for ruby UUID generation:
Ruby code:
~ $ ruby -r securerandom -e 'p SecureRandom.uuid'
"cb7f89a5-e698-471a-8a4a-6ac007c7a66a"
~$ ruby -r securerandom -e 'p SecureRandom.uuid'
"538d3b76-c55a-41b9-9ce6-4c268e5b983e"

I didn't even know this was a thing. :monocle:

Thanks guys!

# ? May 21, 2013 09:47

Smol: Jun 1, 2011; Stat rosa pristina nomine, nomina nuda tenemus.

It was added in 1.9.

# ? May 21, 2013 09:51

Cocoa Crispies: Jul 20, 2001; Vehicular Manslaughter!; Pillbug

Lexicon posted:

In ruby, is there an easy way to tell at the point of execution whether "self" refers to a class or an instance?

self.is_a? Class returns true if self is an instance of Class.

Ruby code:

5.is_a? Class
     # => false
5.is_a? Fixnum
     # => true
Fixnum.is_a? Class
     # => true

# ? May 22, 2013 15:08

Lexicon: Jul 29, 2003; I had a beer with Stephen Harper once and now I like him.

Cocoa Crispies posted:

self.is_a? Class returns true if self is an instance of Class.
Ruby code:
5.is_a? Class
     # => false
5.is_a? Fixnum
     # => true
Fixnum.is_a? Class
     # => true

Perfect, thanks!

# ? May 22, 2013 15:18

raej: Sep 25, 2003; "Being drunk is the worst feeling of all. Except for all those other feelings."

In reference to my cellar list above. How would I go about destroying a Cellared_Beer with the correct variables (size, year) when this is being viewed in the User model?

For instance, the view attached is users/1/cellar

I need the "delete" link to destroy a cellared_beer (which has user_id, beer_id, size, year, created_at, updated_at) that matches that line item (unique on beer_id, size, year)

Only registered members can see post attachments!

# ? May 22, 2013 20:19

Vulture Culture: Jul 14, 2003; I was never enjoying it. I only eat it for the nutrients.

raej posted:

In reference to my cellar list above. How would I go about destroying a Cellared_Beer with the correct variables (size, year) when this is being viewed in the User model?

For instance, the view attached is users/1/cellar

I need the "delete" link to destroy a cellared_beer (which has user_id, beer_id, size, year, created_at, updated_at) that matches that line item (unique on beer_id, size, year)

Using the approach you've chosen, you're overcomplicating things and making your schema really difficult to work with -- if you decide to modify your constraints anywhere in the system, you have lots of things you need to update because of the incredibly tight coupling you've chosen. If I were you, I'd create a single numeric primary key for each combination of (beer_id, size, year) and use simple unique constraints instead of a compound primary key to ensure uniqueness properly.

# ? May 22, 2013 20:23

raej: Sep 25, 2003; "Being drunk is the worst feeling of all. Except for all those other feelings."

Misogynist posted:

Using the approach you've chosen, you're overcomplicating things and making your schema really difficult to work with -- if you decide to modify your constraints anywhere in the system, you have lots of things you need to update because of the incredibly tight coupling you've chosen. If I were you, I'd create a single numeric primary key for each combination of (beer_id, size, year) and use simple unique constraints instead of a compound primary key to ensure uniqueness properly.

Well, each cellared_beer has a unique key... The problem I was having was grouping like beers for display in a cellar. If someone adds a 6-pack of something, I'd rather not have 6 lines for that beer. But I need to be able to decriment that amount when someone decides to drink one of those beers.

# ? May 22, 2013 20:33

Cocoa Crispies: Jul 20, 2001; Vehicular Manslaughter!; Pillbug

raej posted:

Well, each cellared_beer has a unique key... The problem I was having was grouping like beers for display in a cellar. If someone adds a 6-pack of something, I'd rather not have 6 lines for that beer. But I need to be able to decriment that amount when someone decides to drink one of those beers.

On your CellaredBeer model, add a #drink method that decrements the quantity and updates drank_at. If the quantity is zero, keep it around so the user doesn't have to rack their brain over what that one beer they had last month was.

# ? May 22, 2013 22:28

raej: Sep 25, 2003; "Being drunk is the worst feeling of all. Except for all those other feelings."

Cocoa Crispies posted:

On your CellaredBeer model, add a #drink method that decrements the quantity and updates drank_at. If the quantity is zero, keep it around so the user doesn't have to rack their brain over what that one beer they had last month was.

So would it be better to style cellared_beers as id, user_id, beer_id, year, size, amount? Then be able to lower amount every time a beer is removed?

How would that work when say someone buys a 6 pack, then a week later, buys another 6 pack and hasn't drank any? Wouldn't that be 2 lines of 6?

# ? May 22, 2013 23:03

Nybble: Jun 28, 2008; praise chuck, raise heck

I think you need to zoom out a little. What exactly are you trying to measure? Are you trying to measure number of bottles or number of packages? If you had a 6 pack and a 12 pack, what do YOU want to display? 18, 1/6 and 1/12, or both of those options?

That'll change how you model it, and right now I'm not exactly clear on which you'd like.

# ? May 22, 2013 23:26

xtal: Jan 9, 2011; by Fluffdaddy

Lexicon posted:

In ruby, is there an easy way to tell at the point of execution whether "self" refers to a class or an instance? I'm debugging some meta-programming hell (that I didn't write) and self.extend is getting called on a class instead of an instance somehow, and causing class-wide definitions that I don't want to exist. Basically, I want the opportunity to insert in "debugger if self is a class" so I can see where it's being called from. Any thoughts?

Pedantry: everything in Ruby is an instance.

Fixnum.is_a?(Class) is true not because Fixnum is a class per se, but because Fixnum is literally an instance of Class.

# ? May 22, 2013 23:36

raej: Sep 25, 2003; "Being drunk is the worst feeling of all. Except for all those other feelings."

Nybble posted:

I think you need to zoom out a little. What exactly are you trying to measure? Are you trying to measure number of bottles or number of packages? If you had a 6 pack and a 12 pack, what do YOU want to display? 18, 1/6 and 1/12, or both of those options?

That'll change how you model it, and right now I'm not exactly clear on which you'd like.

I want to keep track of the number of like bottles based on beer, year, and size. The 6-pack analogy was just knowledge that most 12oz bottles come in a 6-pack, and a person would be adding many of a like bottle based on that.

# ? May 23, 2013 00:25

Cocoa Crispies: Jul 20, 2001; Vehicular Manslaughter!; Pillbug

raej posted:

So would it be better to style cellared_beers as id, user_id, beer_id, year, size, amount? Then be able to lower amount every time a beer is removed?

How would that work when say someone buys a 6 pack, then a week later, buys another 6 pack and hasn't drank any? Wouldn't that be 2 lines of 6?

Add a Beer#buy(user, quantity) or User#buy(beer, quantity) method that handles the finding/creating and incrementing.

CellaredBeer might belongs_to :user, belongs_to :beer, and have a quantity, size/distribution (i.e. 12oz can, 12oz bottle, 40oz can), bought_at, drank_at, etc.

# ? May 23, 2013 01:20

Lexicon: Jul 29, 2003; I had a beer with Stephen Harper once and now I like him.

xtal posted:

Pedantry: everything in Ruby is an instance. Fixnum.is_a?(Class) is true not because Fixnum is a class per se, but because Fixnum is literally an instance of Class.

As a fellow pedant, thanks for putting me straight

# ? May 23, 2013 04:14

raej: Sep 25, 2003; "Being drunk is the worst feeling of all. Except for all those other feelings."

Cocoa Crispies posted:

Add a Beer#buy(user, quantity) or User#buy(beer, quantity) method that handles the finding/creating and incrementing.

CellaredBeer might belongs_to :user, belongs_to :beer, and have a quantity, size/distribution (i.e. 12oz can, 12oz bottle, 40oz can), bought_at, drank_at, etc.

Can you enlighten me as to what this is called so that I can read up on it more? This sounds like the ticket!

# ? May 23, 2013 04:19

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# ? May 15, 2024 10:39

Cocoa Crispies: Jul 20, 2001; Vehicular Manslaughter!; Pillbug

raej posted:

Can you enlighten me as to what this is called so that I can read up on it more? This sounds like the ticket!

It's called object oriented design: you put methods on objects that match your domain so instead of computer bullshit they're a domain model.

# ? May 23, 2013 17:38

The Something Awful Forums > Discussion > Serious Hardware/Software Crap > The Cavern of COBOL > Ruby on Rails Love-In

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