refactor: Simplify stuff

Squashed commit of the following:

commit b061842
Author: Rafael Espinoza <[email protected]>
Date:   Sun Apr 18 22:36:53 2021 -0700

    refactor: Rename MigrationsConf to Config, reduce usage

    This is another vestige of some overcomplicated design from when I first
    started this project. There was some unnecessary coupling between this
    type, the DSN type (removed in another commit) and the Driver type.

commit 0a01070
Author: Rafael Espinoza <[email protected]>
Date:   Sun Apr 18 20:08:11 2021 -0700

    refactor: Update Driver and remove DSN type

    Reduce the amount of work that a Driver needs to do by having the core
    library take care of the environment variable. Much easier to pass this
    in to the Driver as a regular argument. Another nice thing, you don't
    need to specify the DB_DSN anymore if all you want to do is look at the
    help menu.

    The DSN is now just one environment variable and can be handled by the
    godfish package itself. No need for this creational build pattern thing.

commit be83516
Author: Rafael Espinoza <[email protected]>
Date:   Fri Apr 2 18:06:02 2021 -0700

    refactor: Remove code, clean up stuff

    The DSN.Boot method and ConnectionParams type aren't so useful now that
    you can directly use the data source name.

driver.go

@@ -12,13 +12,11 @@ type Driver interface {
 	// internal reference to that connection for later use. This library might
 	// call this method multiple times, so use the internal reference if it's
 	// present instead of reconnecting to the database.
-	Connect() (*sql.DB, error)
+	Connect(dsn string) (*sql.DB, error)
 	// Close should check if there's an internal reference to a database
 	// connection (a *sql.DB) and if it's present, close it. Then reset the
 	// internal reference to that connection to nil.
 	Close() error
-	// DSN returns data source name info, ie: how do I connect?
-	DSN() DSN
 
 	// AppliedVersions queries the schema migrations table for migration
 	// versions that have been executed against the database. If the schema
@@ -39,43 +37,6 @@ type Driver interface {
 	UpdateSchemaMigrations(dir Direction, version string) error
 }
 
-// NewDriver initializes a Driver implementation by name and connection
-// parameters.
-func NewDriver(dsn DSN, migConf *MigrationsConf) (driver Driver, err error) {
-	return dsn.NewDriver(migConf)
-}
-
-// DSN generates a data source name or connection URL for DB connections. The
-// output will be passed to the standard library's sql.Open method.
-type DSN interface {
-	// Boot takes inputs from the host environment so it can create a Driver.
-	//
-	// Deprecated: Set the DB_DSN environment variable instead of using this.
-	Boot(ConnectionParams) error
-	// NewDriver calls the constructor of the corresponding Driver.
-	NewDriver(*MigrationsConf) (Driver, error)
-	// String uses connection parameters to form the data source name.
-	String() string
-}
-
-// ConnectionParams is what to use when initializing a DSN.
-//
-// Deprecated: Set the DB_DSN environment variable instead of using this.
-type ConnectionParams struct {
-	Encoding string // Encoding is the client encoding for the connection.
-	Host     string // Host is the name of the host to connect to.
-	Name     string // Name is the database name.
-	Pass     string // Pass is the password to use for the connection.
-	Port     string // Port is the connection port.
-	User     string // User is the name of the user to connect as.
-}
-
-// MigrationsConf is intended to lend customizations such as specifying the path
-// to the migration files.
-type MigrationsConf struct {
-	PathToFiles string `json:"path_to_files"`
-}
-
 // AppliedVersions represents an iterative list of migrations that have been run
 // against the database and have been recorded in the schema migrations table.
 // It's enough to convert a *sql.Rows struct when implementing the Driver

drivers/mysql/godfish/main.go

@@ -9,9 +9,7 @@ import (
 )
 
 func main() {
-	var dsn mysql.DSN
-	err := commands.Run(&dsn)
-	if err != nil {
+	if err := commands.Run(mysql.NewDriver()); err != nil {
 		log.Println(err)
 		os.Exit(1)
 	}

drivers/mysql/mysql.go

@@ -3,64 +3,28 @@ package mysql
 import (
 	"database/sql"
 	"fmt"
-	"os"
 	"regexp"
 	"strings"
 
 	my "github.com/go-sql-driver/mysql"
 	"github.com/rafaelespinoza/godfish"
 )
 
-// DSN implements the godfish.DSN interface and defines keys, values needed to
-// connect to a mysql database.
-type DSN struct {
-	godfish.ConnectionParams
-}
-
-var _ godfish.DSN = (*DSN)(nil)
-
-// Boot initializes the DSN from environment inputs.
-func (p *DSN) Boot(params godfish.ConnectionParams) error {
-	p.ConnectionParams = params
-	return nil
-}
-
 // NewDriver creates a new mysql driver.
-func (p *DSN) NewDriver(migConf *godfish.MigrationsConf) (godfish.Driver, error) {
-	return newMySQL(*p)
-}
-
-// String generates a data source name (or connection URL) based on the fields.
-func (p *DSN) String() string {
-	return os.Getenv("DB_DSN")
-}
+func NewDriver() godfish.Driver { return &driver{} }
 
 // driver implements the godfish.Driver interface for mysql databases.
 type driver struct {
 	connection *sql.DB
-	dsn        DSN
-}
-
-var _ godfish.Driver = (*driver)(nil)
-
-func newMySQL(dsn DSN) (*driver, error) {
-	if dsn.Host == "" {
-		dsn.Host = "localhost"
-	}
-	if dsn.Port == "" {
-		dsn.Port = "3306"
-	}
-	return &driver{dsn: dsn}, nil
 }
 
-func (d *driver) Name() string     { return "mysql" }
-func (d *driver) DSN() godfish.DSN { return &d.dsn }
-func (d *driver) Connect() (conn *sql.DB, err error) {
+func (d *driver) Name() string { return "mysql" }
+func (d *driver) Connect(dsn string) (conn *sql.DB, err error) {
 	if d.connection != nil {
 		conn = d.connection
 		return
 	}
-	if conn, err = sql.Open(d.Name(), d.DSN().String()); err != nil {
+	if conn, err = sql.Open(d.Name(), dsn); err != nil {
 		return
 	}
 	d.connection = conn

drivers/mysql/mysql_test.go

@@ -8,5 +8,5 @@ import (
 )
 
 func Test(t *testing.T) {
-	internal.RunDriverTests(t, &mysql.DSN{})
+	internal.RunDriverTests(t, mysql.NewDriver())
 }

drivers/postgres/godfish/main.go

@@ -9,9 +9,7 @@ import (
 )
 
 func main() {
-	var dsn postgres.DSN
-	err := commands.Run(&dsn)
-	if err != nil {
+	if err := commands.Run(postgres.NewDriver()); err != nil {
 		log.Println(err)
 		os.Exit(1)
 	}

drivers/postgres/postgres.go

@@ -2,62 +2,26 @@ package postgres
 
 import (
 	"database/sql"
-	"os"
 
 	"github.com/lib/pq"
 	"github.com/rafaelespinoza/godfish"
 )
 
-// DSN implements the godfish.DSN interface and defines keys, values needed to
-// connect to a postgres database.
-type DSN struct {
-	godfish.ConnectionParams
-}
-
-var _ godfish.DSN = (*DSN)(nil)
-
-// Boot initializes the DSN from environment inputs.
-func (p *DSN) Boot(params godfish.ConnectionParams) error {
-	p.ConnectionParams = params
-	return nil
-}
-
 // NewDriver creates a new postgres driver.
-func (p *DSN) NewDriver(migConf *godfish.MigrationsConf) (godfish.Driver, error) {
-	return newPostgres(*p)
-}
-
-// String generates a data source name (or connection URL) based on the fields.
-func (p *DSN) String() string {
-	return os.Getenv("DB_DSN")
-}
+func NewDriver() godfish.Driver { return &driver{} }
 
 // driver implements the Driver interface for postgres databases.
 type driver struct {
 	connection *sql.DB
-	dsn        DSN
-}
-
-var _ godfish.Driver = (*driver)(nil)
-
-func newPostgres(dsn DSN) (*driver, error) {
-	if dsn.Host == "" {
-		dsn.Host = "localhost"
-	}
-	if dsn.Port == "" {
-		dsn.Port = "5432"
-	}
-	return &driver{dsn: dsn}, nil
 }
 
-func (d *driver) Name() string     { return "postgres" }
-func (d *driver) DSN() godfish.DSN { return &d.dsn }
-func (d *driver) Connect() (conn *sql.DB, err error) {
+func (d *driver) Name() string { return "postgres" }
+func (d *driver) Connect(dsn string) (conn *sql.DB, err error) {
 	if d.connection != nil {
 		conn = d.connection
 		return
 	}
-	if conn, err = sql.Open(d.Name(), d.DSN().String()); err != nil {
+	if conn, err = sql.Open(d.Name(), dsn); err != nil {
 		return
 	}
 	d.connection = conn

drivers/postgres/postgres_test.go

@@ -8,5 +8,5 @@ import (
 )
 
 func Test(t *testing.T) {
-	internal.RunDriverTests(t, &postgres.DSN{})
+	internal.RunDriverTests(t, postgres.NewDriver())
 }

godfish.go

@@ -14,7 +14,16 @@ import (
 
 // Migrate executes all migrations at directoryPath in the specified direction.
 func Migrate(driver Driver, directoryPath string, direction Direction, finishAtVersion string) (err error) {
-	var migrations []Migration
+	var (
+		dsn        string
+		migrations []Migration
+	)
+	if dsn, err = getDSN(); err != nil {
+		return
+	}
+	if _, err = driver.Connect(dsn); err != nil {
+		return
+	}
 	defer driver.Close()
 
 	if finishAtVersion == "" && direction == DirForward {
@@ -23,9 +32,6 @@ func Migrate(driver Driver, directoryPath string, direction Direction, finishAtV
 		finishAtVersion = minVersion
 	}
 
-	if _, err = driver.Connect(); err != nil {
-		return
-	}
 	finder := migrationFinder{
 		direction:       direction,
 		directoryPath:   directoryPath,
@@ -57,17 +63,25 @@ var (
 // ApplyMigration runs a migration at directoryPath with the specified version
 // and direction.
 func ApplyMigration(driver Driver, directoryPath string, direction Direction, version string) (err error) {
-	var mig Migration
-	var pathToFile string
+	var (
+		dsn        string
+		pathToFile string
+		mig        Migration
+	)
+
+	if dsn, err = getDSN(); err != nil {
+		return
+	}
+	if _, err = driver.Connect(dsn); err != nil {
+		return
+	}
 	defer driver.Close()
 
 	if direction == DirUnknown {
 		err = fmt.Errorf("unknown Direction %q", direction)
 		return
 	}
-	if _, err = driver.Connect(); err != nil {
-		return
-	}
+
 	if version == "" {
 		// attempt to find the next version to apply in the direction
 		var limit string
@@ -183,7 +197,11 @@ func runMigration(driver Driver, pathToFile string, mig Migration) (err error) {
 // the database. Running any migration will create the table, so you don't
 // usually need to call this function.
 func CreateSchemaMigrationsTable(driver Driver) (err error) {
-	if _, err = driver.Connect(); err != nil {
+	var dsn string
+	if dsn, err = getDSN(); err != nil {
+		return
+	}
+	if _, err = driver.Connect(dsn); err != nil {
 		return err
 	}
 	defer driver.Close()
@@ -192,7 +210,11 @@ func CreateSchemaMigrationsTable(driver Driver) (err error) {
 
 // Info displays the outputs of various helper functions.
 func Info(driver Driver, directoryPath string, direction Direction, finishAtVersion string) (err error) {
-	if _, err = driver.Connect(); err != nil {
+	var dsn string
+	if dsn, err = getDSN(); err != nil {
+		return
+	}
+	if _, err = driver.Connect(dsn); err != nil {
 		return err
 	}
 	defer driver.Close()
@@ -206,6 +228,11 @@ func Info(driver Driver, directoryPath string, direction Direction, finishAtVers
 	return
 }
 
+// Config is for various runtime settings.
+type Config struct {
+	PathToFiles string `json:"path_to_files"`
+}
+
 // Init creates a configuration file at pathToFile unless it already exists.
 func Init(pathToFile string) (err error) {
 	_, err = os.Stat(pathToFile)
@@ -218,7 +245,7 @@ func Init(pathToFile string) (err error) {
 	}
 
 	var data []byte
-	if data, err = json.MarshalIndent(MigrationsConf{}, "", "\t"); err != nil {
+	if data, err = json.MarshalIndent(Config{}, "", "\t"); err != nil {
 		return err
 	}
 	return os.WriteFile(
@@ -454,3 +481,13 @@ func printMigrations(migrations []Migration) {
 		fmt.Printf("\t%-20s | %-s\n", mig.Version().String(), makeMigrationFilename(mig))
 	}
 }
+
+const dsnKey = "DB_DSN"
+
+func getDSN() (dsn string, err error) {
+	dsn = os.Getenv(dsnKey)
+	if dsn == "" {
+		err = fmt.Errorf("missing environment variable: %s", dsnKey)
+	}
+	return
+}

godfish_test.go

@@ -33,7 +33,7 @@ func TestInit(t *testing.T) {
 	if err = godfish.Init(pathToFile); err != nil {
 		t.Fatalf("something else is wrong with setup; %v", err)
 	}
-	var conf godfish.MigrationsConf
+	var conf godfish.Config
 	if data, err := os.ReadFile(pathToFile); err != nil {
 		t.Fatal(err)
 	} else if err = json.Unmarshal(data, &conf); err != nil {
@@ -54,7 +54,7 @@ func TestInit(t *testing.T) {
 	if err := godfish.Init(pathToFile); err != nil {
 		t.Fatal(err)
 	}
-	var conf2 godfish.MigrationsConf
+	var conf2 godfish.Config
 	if data, err := os.ReadFile(pathToFile); err != nil {
 		t.Fatal(err)
 	} else if err = json.Unmarshal(data, &conf2); err != nil {