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SQL Migrations with Cobra & Golang Migrate

lucasnevespereira profile image Lucas Neves Pereira ・4 min read

Hello dear readers, lately I've been struggling to run database migrations in Golang with sqlite3 but I have found a solution and I want to share it with you guys.

Let's do this

Start by creating a simple project Golang project in your computer

mkdir migration-cli
cd migration-cli
go mod init migration-cli
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Then get the cobra package

go get -u github.com/spf13/cobra
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Open this in your favourite code editor and create and add a main.go file

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Adding Cobra

We are going to start by creating a package cmd with a root.go file.

There we are going to setup a root command for our cli using cobra of course. The name of this cli will be mcli for example purposes.

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SubCommands

Let's create a subcommand named migrate that will have a another up and down subcommand.

migrate.go will be a very simple file, it is like a subroot command that is added to the root command 🙂

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Now we can create migrateUp.go and migrateDown.go that are subcommands for migrate. The difference is that up and down will have an extra Run cobra property where we are going to write the actual logic to run our migrations.

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To finish setting this up, in our main.go we need to call Execute() from our cmd/root.go file.

To test if the commands are called you can either build your program with a custom name and then call it

go build -o mcli
./mcli migrate up
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or for now just use go run

go run main.go migrate up
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Setup Database

I'll be using sqlite3 for the database, I'm gonna start by creating a database package with a config file.

In that config file I'll write a Open method that will return an instance of my database.

For that I'll need the sqlite3 driver package

go get -u github.com/mattn/go-sqlite3
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Now we can call database.Open() in our migrate subcommands to test the database connection.

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go build -o mcli
./mcli migrate up
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It's working and as you can see it created a myDB file.
I will open this file in DB Browser for Sqlite that is a GUI for SQLITE.

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Okay we know how to open our database let's write our migrations.

Migrations

In a new directory migrations I am going to create a 1_install.up.sql file and a 1_install.down.sql, this syntax will allow golang migrate to know the version of our migration file as well as the action.

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Now let's add golang migrate

go get -u github.com/golang-migrate/migrate/v4

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Back to migrateUp.go we are going to write the logic to run our up migration using golang migrate package.

Let's build the program and run ./mcli migrate up again to test this 🙂

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Seems to be working, if we open the myDB file in DB Browser for Sqlite again we should see our tables.

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Perfect! Now let's do the same thing for migrate down the logic is basically the same but instead of call the golang migrate built in func Up() we call Down().

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Let's test migrate down 👍🏼

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Now if you open your myDB file again our tables should be gone.

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Conclusion

Okay, that's it! I hope this article will help 😀
The code source is here.
Youtube video here.

See you soon 👋🏼

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