Creating an In Stock Report

6:24 with Jason Seifer

Now that we know all about our stock counts and what is in stock, we're going to create a report method to display it. We'll keep this method in our `Inventoryable` module so we can use it in all of our classes.

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Our store code is coming along! This is the complete version at the end of the video.

module Inventoryable

  def self.included(klass)
    klass.extend(ClassMethods)
    klass.extend(Enumerable)
  end

  module ClassMethods
    def create(attributes)
      object = new(attributes)
      instances.push(object)
      return object
    end

    def instances
      @instances ||= []
    end

    def each(&block)
      instances.each(&block)
    end

    def in_stock_report
      puts "#{self.to_s} In Stock Report"
      reportable = instances.select{ |instance| instance.in_stock? }
      reportable.each do |item|
        line = []
        line.push("Item: #{item.attributes[:name]}")
        line.push("Stock: #{item.stock_count}")
        if item.attributes.include?(:size)
          line.push("Size: #{item.attributes[:size]}")
        end
        puts line.join("\t")
      end
      puts "\n"
    end
  end

  def stock_count
    @stock_count ||= 0
  end

  def stock_count=(number)
    @stock_count = number
  end

  def in_stock?
    stock_count > 0
  end

end

class Shirt
  include Inventoryable
  attr_accessor :attributes

  def initialize(attributes)
    @attributes = attributes
  end
end

class Pant
  include Inventoryable
  attr_accessor :attributes

  def initialize(attributes)
    @attributes = attributes
  end
end

class Accessory
  include Inventoryable
  attr_accessor :attributes

  def initialize(attributes)
    @attributes = attributes
  end
end

shirt = Shirt.create(name: "MTF", size: "L")
shirt.stock_count = 10

shirt = Shirt.create(name: "MTF2", size: "L")

shirt = Shirt.create(name: "MTF", size: "M")
shirt.stock_count = 9

pant = Pant.create(name: "Jeans", size: "M")
pant.stock_count = 2

pant = Pant.create(name: "Jeans", size: "S")
pant.stock_count = 4

accessory = Accessory.create(name: "Belt", size: "M")
accessory.stock_count = 1

accessory = Accessory.create(name: "Belt", size: "L")
accessory.stock_count = 1

accessory = Accessory.create(name: "Necklace")
accessory.stock_count = 1

Shirt.in_stock_report
Pant.in_stock_report
Accessory.in_stock_report

0:00
So, when we last left off, we had created these create and
0:05
instances class methods and
0:07
then extended the classes with them when our inventoriable module was included.
0:13
So now, let's go ahead and I have included the inventoriable module
0:19
in the pant class and the accessory class.
0:24
So, now lets go ahead and create some stock counts to work with.
0:30
So, we’re gonna actually create some items and I’m just gonna paste this in.
0:34
So, we’re gonna sell some Mike the Frog shirts, some jeans, and
0:39
some belts, and a necklace.
0:42
Now one thing that you'll notice right here
0:45
is that the necklace does not have a size associated with it.
0:49
That's gonna come into play very, very shortly.
0:53
So what we're going to do is we wanna create a report
0:57
of everything that is currently in stock.
1:00
And we wanna do that at the class level.
1:04
So we would say shirt dot in stock report, and
1:08
we want that to return a list of everything that we have in stock.
1:12
Now since it's going to be a class method,
1:14
we're going to put it inside of our class methods module.
1:18
Now, let's just go ahead and call this in_stock_report.
1:26
So first we'll print to the screen the name of the class that we're working with
1:30
which we can just do by typing self.to_s, in stock report.
1:38
Now what we wanna do is select every instance that is in stock.
1:44
So, we already have this in stock method,
1:47
wouldn't it be great if we could just say instances.select,
1:53
instance, and then say it's in stock.
2:00
That would be great, but somehow we have to get a numerable in here.
2:04
Well, we can do that the same way that we extended the class methods.
2:10
We can also extend it with enumerable.
2:15
So, when our inventoriable module gets included at the class level,
2:20
we get all of these class methods and the enumerable module.
2:24
Since we're getting the enumerable model,
2:27
that means we need to define our own each method.
2:33
And let's go ahead and look back at our enumerable work and
2:36
see what we did in that one.
2:39
We just defined a method called each, grabbed the block,
2:44
and passed it into the players object.
2:48
Well we can do the same thing here, and just pass it in to the instances.
2:57
So now, whatever it is, if it's shirts,
3:00
we'll just be running this against the shirts.
3:03
If it's pants, same thing, and same thing with accessories.
3:07
So we'll just say we're reporting on these things, so these are reportable,
3:14
and now all we have to do is print them out.
3:17
We've gone through and selected them, so
3:19
we know we've got the ones that are in stock.
3:25
And, what we'll do is something kind of interesting.
3:28
We're just gonna iterate through them and we're gonna create
3:32
an array of what we wanna report on and then print that array out.
3:37
But, what we wanna do is, also remember how the size wasn't necessarily in here?
3:45
We're gonna put a little if statement there.
3:47
This will make a lot more sense in just a moment.
3:50
We'll say align is an empty array, and we will push the item name here,
3:57
and we have to grab the attributes for the name.
4:06
And we will also say stock is the item's stock count
4:15
Now remember how not every single item has a size, like this necklace right here?
4:21
We’re not gonna print that out, if the item doesn’t have the size attribute.
4:26
So, we’ll say if the item attributes, which is just a hash,
4:32
include the size then we can print it out.
4:49
And now we can just print out the line and we'll separate it with a tab character.
4:58
And then we'll end this whole thing with a new line.
5:03
Actually we need to interpolate that string.
5:06
Okay.
5:08
So now let's go ahead and call this and we'll do an in stock report for
5:13
our shirts.
5:16
And let's just see what happens.
5:18
I'm going to make this a little bit bigger.
5:20
Uh-oh.
5:22
Syntax error, expecting keyword_end.
5:25
Now when that happens, it usually means that we forgot an end somewhere.
5:30
So let's go ahead and see if we can figure that out.
5:34
All right, it looks like we needed a little if statement here.
5:38
Let me clear the screen and run that again.
5:41
Okay.
5:42
And that worked just like we expected it to.
5:44
We have an In Stock Report for our shirts.
5:46
So let's go ahead and do the same thing for pants, and
5:52
for our accessories as well.
5:58
I'm gonna clear my screen and run this again.
6:02
Make this a little bit bigger so that we can see.
6:03
Clear one more time.
6:06
Okay, we have our Shirt In Stock Report, our Pant In Stock Report,
6:10
and our Accessory In Stock Report.
6:14
And you'll notice for our necklace item, this does not list the size,
6:18
which is exactly what we wanted.
6:20
In our next video, we're going to clean this up just a little bit.

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Creating an In Stock Report

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