Understanding the Gemfile and Gems

Quick reference

• 00:05 In this video, I wanna talk a little about Gemfile.
• 00:07 And we've looked at this earlier, but this just a really important file.
• 00:11 And we're gonna be using this a whole lot throughout this course and
• 00:14 throughout your Rails coding career.
• 00:17 So you wanna be comfortable with this Gemfile.
• 00:19 And earlier we went through here and we cleaned up all the comments, so
• 00:22 it's much easier to read.
• 00:23 I touched on this earlier, but let's talk about this, what exactly is the Gemfile?
• 00:28 Well, the great thing about Ruby on Rails is it allows you to do all kinds of stuff
• 00:32 without writing code yourself.
• 00:34 You can take things that other people have created, and import them into your
• 00:38 project, and use them without having to write all of the stuff.
• 00:41 And we're gonna see this pretty soon when we start adding things.
• 00:43 And those things that we import, they're called gems.
• 00:46 It's, you know, Ruby has a gem, it's a whole theme, right?
• 00:50 So anytime we wanna add something from a third party, we're gonna add a gem.
• 00:54 And we're gonna do it to this file.
• 00:56 And every time we add something we have to run the command bundle install,
• 01:01 and what that does is it downloads everything and it installs it.
• 01:06 You can see we haven't added anything, we're complete,
• 01:09 we're up to date, so it didn't do anything.
• 01:12 But it did go through here and check.
• 01:13 Now, a lot of these things have dependencies.
• 01:16 So there's one gem here, but it might need five other gems in order to work itself.
• 01:21 The bundle install command will go and find all of the other files that you need,
• 01:24 it'll download them, and you'll be up and running, and good to go.
• 01:27 The question becomes where do you find all these gems, and how do you use them?
• 01:31 Well, there a website called rubygems.org and
• 01:35 it is huge, it is the main repository of all gems ever.
• 01:40 And people can add there own gems and other people can download and use them.
• 01:44 And you can see, 12 billion downloads and counting, this is the place to go.
• 01:49 So you noticed earlier we added Postgres which is pg.
• 01:54 You can see we added it to allow Heroku to play nice with our app.
• 01:58 Well, if I type in pg, you see here is 31 million downloads,
• 02:03 and if we click on this, see here's the Gemfile.
• 02:07 This is the line of code, you'll copy this, and then you'll come back here, and
• 02:11 you'll paste it in, Control V.
• 02:13 And it pops it in.
• 02:15 Right here I just typed in pg, but
• 02:16 you see this squiggly line on the other side of it.
• 02:19 That signifies a version number.
• 02:22 So this is version 0.19 of the pg value.
• 02:26 You don't always have to do that.
• 02:28 It's good that you do that in the future.
• 02:32 When I added pg we didn't really need a version number, I knew that already so
• 02:36 I didn't add one.
• 02:37 But in the future you will add definitely a version number to your Gemfiles.
• 02:40 Basically, just copy and paste this, and you'll see as we move forward and
• 02:44 start using the Gemfile, this becomes second nature to you.
• 02:48 But looking through here there's some interesting stuff.
• 02:50 There's usually a Homepage and a Documentation.
• 02:52 And a lot of times the Homepage and the Documentation page are the same page.
• 02:56 But if you click on here, I don't like the look of that.
• 02:58 Let's go to the Homepage.
• 03:00 You'll often find installation instructions because it's
• 03:04 not always as easy as just typing in a name into your Gemfile and
• 03:07 then running the bundle install.
• 03:09 A lot of times there's additional steps you have take and
• 03:12 the Read Me file will tell you that.
• 03:14 So, it's always important to go ahead and read through the Read Me file.
• 03:17 Another thing to mention is a lot of times there's a bunch of different listings
• 03:21 that look similar, and it can be confusing which one you need to download.
• 03:25 A good rule of thumb is you almost always want the one with the most downloads.
• 03:29 So pg has almost 32 million downloads.
• 03:33 The next one down is 1 million.
• 03:36 You can guess that this is the one we want and this is not the one we want.
• 03:40 So that's something sort of useful to keep in mind, but really simple to use.
• 03:44 That's one of the great things about Rails.
• 03:46 It allows you to add all kinds of cool stuff to your apps without
• 03:49 writing code yourself without inventing things yourself.
• 03:52 You can take gems that other people have created and use them, just drag and
• 03:56 drop, easy.
• 03:57 So you'll see as we move forward, we'll use this a lot.
• 04:00 But right now, just sorta get familiar with this file, and
• 04:04 yeah, that's all for this video.

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