gogjango/gjango

package migration

import (
    "flag"
    "fmt"
    "log"
    "os"

    migrations "github.com/go-pg/migrations/v7"
    "github.com/go-pg/pg/v9"
    "github.com/go-pg/pg/v9/orm"
    "github.com/gogjango/gjango/config"
    "github.com/gogjango/gjango/model"
)

const usageText = `This program runs command on the db. Supported commands are:
  - init - creates version info table in the database
  - up - runs all available migrations.
  - up [target] - runs available migrations up to the target one.
  - down - reverts last migration.
  - reset - reverts all migrations.
  - version - prints current db version.
  - set_version [version] - sets db version without running migrations.
  - create_schema [version] - creates initial set of tables from models (structs).
Usage:
  go run *.go <command> [args]
`

// Run executes migration subcommands
func Run(args ...string) error {
    fmt.Println("Running migration")

    p := config.GetPostgresConfig()

    // connection to db as postgres superuser
    dbSuper := config.GetPostgresSuperUserConnection()
    defer dbSuper.Close()

    // connection to db as POSTGRES_USER
    db := config.GetConnection()
    defer db.Close()

    createUserIfNotExist(dbSuper, p)

    createDatabaseIfNotExist(dbSuper, p)

    if flag.Arg(0) == "create_schema" {
        createSchema(db, &model.Company{}, &model.Location{}, &model.Role{}, &model.User{}, &model.Verification{})
        os.Exit(2)
    }

    oldVersion, newVersion, err := migrations.Run(db, args...)
    if err != nil {
        exitf(err.Error())
    }
    if newVersion != oldVersion {
        fmt.Printf("migrated from version %d to %d\n", oldVersion, newVersion)
    } else {
        fmt.Printf("version is %d\n", oldVersion)
    }
    return nil
}

func usage() {
    fmt.Print(usageText)
    flag.PrintDefaults()
    os.Exit(2)
}

func errorf(s string, args ...interface{}) {
    fmt.Fprintf(os.Stderr, s+"\n", args...)
}

func exitf(s string, args ...interface{}) {
    errorf(s, args...)
    os.Exit(1)
}

func createUserIfNotExist(db *pg.DB, p *config.PostgresConfig) {
    statement := fmt.Sprintf(`SELECT * FROM pg_roles WHERE rolname = '%s';`, p.User)
    res, _ := db.Exec(statement)
    if res.RowsReturned() == 0 {
        statement = fmt.Sprintf(`CREATE USER %s WITH PASSWORD '%s';`, p.User, p.Password)
        _, err := db.Exec(statement)
        if err != nil {
            fmt.Println(err)
        } else {
            fmt.Printf(`Created user %s`, p.User)
        }
    }
}

func createDatabaseIfNotExist(db *pg.DB, p *config.PostgresConfig) {
    statement := fmt.Sprintf(`SELECT 1 AS result FROM pg_database WHERE datname = '%s';`, p.Database)
    res, _ := db.Exec(statement)
    if res.RowsReturned() == 0 {
        fmt.Println("creating database")
        statement = fmt.Sprintf(`CREATE DATABASE %s WITH OWNER %s;`, p.Database, p.User)
        _, err := db.Exec(statement)
        if err != nil {
            fmt.Println(err)
        } else {
            fmt.Printf(`Created database %s`, p.Database)
        }
    }
}

func createSchema(db *pg.DB, models ...interface{}) {
    for _, model := range models {
        opt := &orm.CreateTableOptions{
            IfNotExists:   true,
            FKConstraints: true,
        }
        err := db.CreateTable(model, opt)
        if err != nil {
            log.Fatal(err)
        }
    }
}