Goravel models and migrations with Postgres

Part 4 of the Goravel series. The original on DevChalk has the colour-matched code, the figures and the full diffs. Code for this part: krishankumar01/goravel-taskflow/tree/part-04.

TaskFlow reads requests, but it has nowhere to keep anything yet. In this part we create the users table from the database design. We write a model, and Goravel writes the migration from it.

Start from the Reading Request Data code:

git clone https://github.com/krishankumar01/goravel-taskflow
cd goravel-taskflow
git checkout part-03
cp .env.example .env
go run . artisan key:generate
docker compose up -d

The model

A model is a Go struct that stands for one table. Create one for users:

$ go run . artisan make:model User
 SUCCESS  Model created successfully

This creates app/models/user.go:

app/models/user.go

package models

import (
    "github.com/goravel/framework/database/orm"
)

type User struct {
    orm.Model
}

orm.Model gives every model an id and two timestamps: when the row was created and when it was last updated. Goravel fills the timestamps for you when a row is saved. A model named User uses a table named users.

Now add the fields from the design:

app/models/user.go

 package models

 import (
    "github.com/goravel/framework/database/orm"
 )

+type Role string
+
+const (
+   RoleManager Role = "manager"
+   RoleMember  Role = "member"
+)
+
 type User struct {
    orm.Model
+   Name     string `gorm:"size:255;not null"`
+   Email    string `gorm:"size:255;unique;not null"`
+   Password string `gorm:"size:255;not null"`
+   Role     Role   `gorm:"type:enum('manager','member');default:'member';not null"`
 }

• Email is unique, so two users can never share an email.
• Role has its own type with two values, manager and member. If no role is given, the database uses member.
• In code you write models.RoleManager instead of the string "manager". If you mistype RoleManager, the build fails and tells you. If you mistype "manager", it builds fine and the bug shows up later.

The GORM tags after each field describe its column: size:255 is the maximum length, and not null says it must have a value. Password will hold a hashed password, never the real one. We hash it when we build register and login.

Goravel does not create or change tables from these tags while the app runs. The tags only matter when make:migration reads them to write a migration.

Other tags make:migration understands:

Here is a model that tries a different tag on each field. It is only an example, so do not add it to TaskFlow:

app/models/probe.go

type Probe struct {
    orm.Model
    Title  string  `gorm:"size:100"`
    Body   string  `gorm:"type:text"`
    Nick   *string `gorm:"size:50"`
    Points int     `gorm:"default:0"`
    Done   bool    `gorm:"default:false"`
    Code   string  `gorm:"size:20;uniqueIndex"`
    Status string  `gorm:"size:20;index"`
    Note   string  `gorm:"size:255;comment:shown to the user"`
    DueAt  *string `gorm:"column:due_on;size:10"`
    Price  float64 `gorm:"type:decimal;precision:10;scale:2"`
    Meta   string  `gorm:"migration:json"`
}

And what make:migration -m Probe wrote for it:

return facades.Schema().Create("probes", func(table schema.Blueprint) {
    table.TimestampTz("created_at").Nullable()
    table.TimestampTz("updated_at").Nullable()
    table.BigIncrements("id")
    table.String("title", 100)
    table.Text("body")
    table.String("nick", 50).Nullable()
    table.BigInteger("points").Default(0)
    table.Boolean("done").Default(false)
    table.String("code", 20)
    table.String("status", 20)
    table.String("note", 255).Comment("shown to the user")
    table.String("due_on", 10).Nullable()
    table.Decimal("price").Places(2).Total(10)
    table.Json("meta")

    table.Unique("code").Name("idx_probes_code")
    table.Index("status").Name("idx_probes_status")
})

• A pointer field, like *string, makes a column nullable. Every other column is not null, with or without a not null tag.
• Give a decimal its size with precision and scale. If you write type:decimal(10,2) instead, the size is lost.
• uniqueIndex works like unique, but the index is named idx_<table>_<column> instead of <table>_<column>_unique.
• migration: takes the name of a schema builder method, so migration:json calls table.Json.

The migration

A migration is a Go file with two methods: Up makes a change to the database, and Down undoes it. You could create the table by hand in Postgres, but then it would only exist on your machine. A migration lives in the project with the code, so every copy of TaskFlow gets the same table.

Goravel can write that file for you from the model. -m User tells it which model to read. If you run it now, it fails:

$ go run . artisan make:migration create_users_table -m User
ERROR   create migration failed: model User not found in registered models

Goravel only knows the models you tell it about, because Go cannot look up a type by its name while the program runs. Register User in bootstrap/app.go:

bootstrap/app.go

 package bootstrap

 import (
+   "github.com/goravel/framework/contracts/database/schema"
    contractsfoundation "github.com/goravel/framework/contracts/foundation"
    "github.com/goravel/framework/foundation"

+   "taskflow/app/facades"
+   "taskflow/app/models"
    "taskflow/config"
    "taskflow/routes"
 )

 func Boot() contractsfoundation.Application {
    return foundation.Setup().
        WithMigrations(Migrations).
        // ... 4 lines not shown
        WithProviders(Providers).
        WithConfig(config.Boot).
+       WithCallback(func() {
+           facades.Schema().Extend(schema.Extension{
+               Models: []any{models.User{}},
+           })
+       }).
        Create()
 }

WithCallback takes a function that runs during startup, after the facades are ready. Inside it, Extend adds User to the models Goravel knows. Run the command again:

$ go run . artisan make:migration create_users_table -m User
SUCCESS  Created Migration: create_users_table
 SUCCESS  Migration registered successfully

It writes the migration and adds it to the list in bootstrap/migrations.go. The file name, the struct and the signature include the time you ran the command, so yours will have a different number:

bootstrap/migrations.go

 // ... 8 lines not shown
 func Migrations() []schema.Migration {
    return []schema.Migration{
        &migrations.M20210101000001CreateJobsTable{},
+       &migrations.M20261022221906CreateUsersTable{},
    }
 }

This is what Goravel wrote:

database/migrations/20261022221906_create_users_table.go

package migrations

import (
    "github.com/goravel/framework/contracts/database/schema"

    "taskflow/app/facades"
)

type M20261022221906CreateUsersTable struct{}

// Signature The unique signature for the migration.
func (r *M20261022221906CreateUsersTable) Signature() string {
    return "20261022221906_create_users_table"
}

// Up Run the migrations.
func (r *M20261022221906CreateUsersTable) Up() error {
    if !facades.Schema().HasTable("users") {
        return facades.Schema().Create("users", func(table schema.Blueprint) {
            table.TimestampTz("created_at").Nullable()
            table.TimestampTz("updated_at").Nullable()
            table.BigIncrements("id")
            table.String("name", 255)
            table.String("email", 255)
            table.String("password", 255)
            table.Enum("role", []any{"manager", "member"}).Default("member")

            table.Unique("email")
        })
    }

    return nil
}

// Down Reverse the migrations.
func (r *M20261022221906CreateUsersTable) Down() error {
    return facades.Schema().DropIfExists("users")
}

Up only creates the table if it is not there yet, and Down drops it.

Every column comes from the model:

• created_at, updated_at and id come from orm.Model.
• The unique email became table.Unique("email").
• The role became table.Enum, with member as its default.

Only the two timestamps have Nullable(). Every other column is not null already, so the not null tags change nothing here. They only matter on a pointer field, which would otherwise be nullable. We keep them because they show that each column needs a value.

Run the migration

If Postgres is not running, start it with docker compose up -d. Then run the migrations:

$ go run . artisan migrate
  INFO    Running migration
  INFO    Running: 20210101000002_create_jobs_table
  INFO    Running: 20261022221906_create_users_table
 SUCCESS  Migration success

The jobs migration runs too. It came with the Queue facade we picked when we created the project, and it creates two tables, jobs and failed_jobs. Our queue runs on Redis, so it never uses jobs, but Goravel still records failed jobs in failed_jobs.

Its file and struct say 20210101000001, but it reports itself as 20210101000002. That is in the file Goravel generated, and it does no harm.

To see what has run:

$ go run . artisan migrate:status
  Migration name .............................................. Batch / Status
  20210101000002_create_jobs_table ................................... [1] Ran
  20261022221906_create_users_table .................................. [1] Ran

Each migrate run is one batch, numbered one higher than the last. Both of ours ran in batch 1. To see the table itself:

$ go run . artisan db:table users
  public.users ...............................................................
  Columns .................................................................. 7
  Size .............................................................. 0.023 MB
  Column ................................................................ Type
  created_at timestamptz, nullable ............... timestamp(0) with time zone
  updated_at timestamptz, nullable ............... timestamp(0) with time zone
  id autoincrement, int8 ............ nextval('users_id_seq'::regclass) bigint
  name varchar ........................................ character varying(255)
  email varchar ....................................... character varying(255)
  password varchar .................................... character varying(255)
  role varchar ............ 'member'::character varying character varying(255)
  Index ......................................................................
  users_email_unique email ..................................... btree, unique
  users_pkey id ....................................... btree, unique, primary

Gotcha db:table says role is varchar, not an enum. On Postgres, Goravel stores an enum as a varchar column with a check that only lets the allowed values in. Try a role that is not allowed:

$ docker compose exec postgres psql -U goravel -d taskflow \
    -c "INSERT INTO users (name, email, password, role) VALUES ('Ana', '[e-mail]', 'x', 'admin');"
ERROR:  new row for relation "users" violates check constraint "users_role_check"

Rolling back a migration

When a migration is wrong, you roll it back, fix it, and run it again. migrate:rollback runs Down for the last batch:

$ go run . artisan migrate:rollback
  INFO    Rolling back migration
  INFO    Rolled back: 20261022221906_create_users_table
  INFO    Rolled back: 20210101000002_create_jobs_table
 SUCCESS  Migration rollback success

Both migrations were undone, not only the users one. A rollback undoes the whole last batch, and both migrations ran in batch 1. migrate:status now shows both as pending:

$ go run . artisan migrate:status
  Migration name .............................................. Batch / Status
  20210101000002_create_jobs_table ................................... Pending
  20261022221906_create_users_table .................................. Pending

To undo only the last migration, add --step=1.

Run migrate again and both are back:

$ go run . artisan migrate
  INFO    Running migration
  INFO    Running: 20210101000002_create_jobs_table
  INFO    Running: 20261022221906_create_users_table
 SUCCESS  Migration success

TaskFlow now has a users table, created from its model. There is no table for tasks yet.

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Previous: 03. Reading Request Data
Next: 05. Relationships: Belongs To
Series: Goravel