Building data-driven web apps with Pyramid and SQLAlchemy Transcripts
Chapter: Database migrations with Alembic
Lecture: Getting started with Alembic
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Before we actually get started here
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I want to just do a quick sync up on where we are
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on the GitHub Repo and the source code
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that you get for this course.
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So over here in the GitHub Repo, we are now moving on
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to Chapter 11, Migrations.
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We'll be working in Final.
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Start of course, is where we're starting
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final, whatever we're going to do in the end
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that's what it's going to turn out to be.
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Now in order to use Alembic we need it installed.
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We need to make sure that we have the right
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virtual directory, which I've already created
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for this version of our website.
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We need to make sure that it's active.
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So I'm going to say . venv/bin/activate, remember
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forget the dot, scripts not bin, on Windows.
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Alright, so now looks like we're using
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the one in PyPI_migrations. Great.
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In order to use Alembic we have to, well, have it installed.
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So pip install alembic.
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Boom, looks like it's installed. Excellent.
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Now down here you need to make sure that
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you are in the folder that has your PyPI folder
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and the two ini. So this right here is our web app.
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We're going to put this next to our web app
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not actually deployed within the sort of request space
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of our web app. So we have Alembic installed.
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The next thing to do is to
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build some basic project structure.
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And this structure is going to allow us to configure Alembic
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and it will keep track of the various versions
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and how to evolve from one to the other.
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So the way we do that is we invoke Alembic.
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We tell it to init, and we have to give it
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a folder to create
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and the convention is to use the same name Alembic
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so you will see the Alembic folder.
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Here we go, it's gone and created that
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and it's done a couple of things.
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It's created the folder and an Alembic.ini.
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Excellent, so it says we're going to need to edit that
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and that's true, we're going to need to edit that.
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But now if we look over here, we'll see
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an Alembic folder and we'll see an Alembic.ini
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and if we tree Alembic, you can see
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it just has a couple of things.
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It has a read.me, it has a mako
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which is a template it uses
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to generate the SQL statements, actually
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that it's going to run.
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It has an environment, which allows us to plug in
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our SQLAlchemy models
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and it has a versions folder
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which is going to keep track of where things are.
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So as we use Alembic, we'll start to build up things there.
