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Let's take an existing Rails app, and convert it from using SQLite to PostgreSQL.
In your terminal:
git clone https://github.com/treehouse-projects/rails-guestbook.git guestbook
Edit the project Gemfile:
# Replace:
gem 'sqlite3'
# With:
gem 'pg', '~> 0.18'
In your terminal:
bundle install
Edit config/database.yml:
default: &default
adapter: postgresql
encoding: unicode
pool: 5
development:
<<: *default
database: guestbook_development
username: <YOUR_POSTGRESQL_USER_NAME>
test:
<<: *default
database: guestbook_test
username: <YOUR_POSTGRESQL_USER_NAME>
production:
<<: *default
database: guestbook_production
username: deploy
In your terminal:
bin/rails db:setup
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Next we're going to need to update our
rails app to use post press instead of
0:00
sequel line.
0:03
So we're going to need to first and
use the postgres gem.
0:04
So I'm going to go here
into our apps Gemfile and
0:09
you see here a line that says, Use sqlite3
as the database for Active Record.
0:12
We wanna use the pg gem instead.
0:16
So I'm gonna replace splite3 with pg, and
0:18
then we're gonna want
a particular version.
0:20
So, I'm going to use the so-called
twiddle wakka syntax,
0:23
which will lock it to
a particular minor version.
0:27
So, I'm gonna use the latest
version that's available
0:31
right now 0.18, save that.
0:36
And now,
0:40
here in the app directory I need to run
bundle install to install the new gems.
0:41
Next I'm going to need to edit
the database.yml file within the config
0:49
directory to tell it to connect
to postgres instead of sqlite.
0:53
So let's delete all these comments here
at the top that talk about sqlite and
0:58
here in the default set of options we're
gonna set the adapter not to sqlite3,
1:04
but to postgresql.
1:10
It's going to want to know
what encoding to save text as.
1:12
And we don't want it using ASCII
we want it using unicode, so
1:17
that we can save characters
from other languages.
1:20
We'll go and leave the pool config
setting, and remove the time out here.
1:24
Now let's go on and
1:30
edit our particular environments which
we'll use the default settings as a basis.
1:32
For our development database we want
to use not this sqlite database, but
1:37
a postgres database named guestbook,
1:41
which is the name of our app,
underscore development.
1:44
Unlike sqlite, postgres supports multiple
users updating the same database, so
1:50
we need to tell it what username
to expect updates to come from.
1:54
So I'm gonna add a username, setting and
I'll use my developer account name, jay.
1:57
We'll do the same for
the test environment.
2:05
Tell it not to look at
a sqlite database file but
2:07
a postgres database named guestbook_test.
2:11
That's guestbook_test as opposed
to guestbook development,
2:15
which it was in
the development environment.
2:19
And again we're going to need
a user name setting of jay,
2:23
which I'll just copy down from
the development environment.
2:26
And last up is production,
2:30
which again will update it
to say guestbook_production.
2:32
But for the production environment we
don't want to use a username matching our
2:38
development name.
2:43
We're gonna want the username
that's responsible for
2:44
maintenance of our application.
2:47
That's going to be the deploy
user in this case.
2:48
Save that and we're done.
2:53
So we set our rails app up to
use a postgres database ,now
2:55
let's actually create that database.
2:58
We're going to need to from our app
to rectory run the command bin/rails
3:00
db:setup and what this will do,
is it'll create both the development, and
3:05
the test databases, and
it will load the schema into them.
3:10
Loading the scheme is actually going to
be more efficient and safer than actually
3:14
running all our migrations since
this is a brand new database.
3:17
So let's run that command.
3:22
It'll create the databases and
set up all the tables for us.
3:25
Next, let's run the rails server and
try the app out, bin/rails server,
3:30
go to our browser, and we'll visit
localhost:3000, where the app is running.
3:36
We've shown an app like this previously,
3:45
it's just a simple guestbook app that can
collect signatures from your visitors.
3:47
The list of signatures is totally
blank since this is a new database, so
3:52
let's create a signature now.
3:55
Hello, PostgresQLI.
3:57
And there it is.
4:01
And there it is in our list.
4:03
Create another one.
4:05
And it looks like we're able to
write signatures of that base and
4:13
read them back out.
4:15
We can also view the contents of
the postgres database directly.
4:17
Just let me quit out of the server here.
4:22
And to connect to the database I'm
gonna run the command bin/rails db.
4:25
This is a command built into rails
that takes whatever database you
4:30
currently have set up and connects to it
using that databases command line program.
4:33
So when I run the rails db commanded,
4:38
it'll connect me to
the postgres terminal program.
4:40
From there I can run sequel commands
like select * from signatures;
4:43
And we're able to see all the records
that have been created via the web app.
4:51
Only when I exit the postgres
terminal we can type backslash q, or
4:56
just hold CNTRL+D.
5:00
So that's it.
5:02
Our app seems to be working with
the postgres database in the development
5:03
environment.
5:06
Next we're gonna show you how
to set it up in production.
5:07
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