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migrator: add functional options
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This allows customizing migrator behaviour by exposing it's configurable
parts through functional options. This change starts by adding a
`Migrations` and `TableName` options to fullfil current requirements.

Closes #13
Superseeds #14
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@glerchundi @lopezator
glerchundi authored and lopezator committed Aug 11, 2019
1 parent 32f7aaa commit 400b0c9
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Showing 4 changed files with 109 additions and 74 deletions.
4 changes: 2 additions & 2 deletions Makefile
View file
Original file line number Diff line number Diff line change
Expand Up @@ -21,7 +21,7 @@ prepare: setup-env mod-download
.PHONY: mod-download
mod-download:
@echo "Running download..."
go mod download GOPROXY="$(GOPROXY)"
GOPROXY="$(GOPROXY)" go mod download

.PHONY: sanity-check
sanity-check: golangci-lint
Expand All @@ -34,4 +34,4 @@ golangci-lint:
.PHONY: test
test:
@echo "Running tests..."
2>&1 POSTGRES_URL="$(POSTGRES_URL)" MYSQL_URL="$(MYSQL_URL)" go test -v -tags="unit integration" -coverprofile=coverage.txt -covermode=atomic
2>&1 POSTGRES_URL="$(POSTGRES_URL)" MYSQL_URL="$(MYSQL_URL)" go test -v -tags="unit integration" -coverprofile=coverage.txt -covermode=atomic
20 changes: 11 additions & 9 deletions README.md
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Original file line number Diff line number Diff line change
Expand Up @@ -49,15 +49,17 @@ import (

func main() {
m := migrator.New(
&migrator.Migration{
Name: "Create table foo",
Func: func(tx *sql.Tx) error {
if _, err := tx.Exec("CREATE TABLE foo (id INT PRIMARY KEY)"); err != nil {
return err
}
return nil
Migrations(
&migrator.Migration{
Name: "Create table foo",
Func: func(tx *sql.Tx) error {
if _, err := tx.Exec("CREATE TABLE foo (id INT PRIMARY KEY)"); err != nil {
return err
}
return nil
},
},
},
),
)

// Migrate up
Expand All @@ -72,7 +74,7 @@ func main() {
```

Notes on examples above:
- Migrator creates/manages a table named `migrations` to keep track of the applied versions
- Migrator creates/manages a table named `migrations` to keep track of the applied versions. However, if want to customize the table name `TableName("my_migrations")` can be also used.

### Looking for more examples?

Expand Down
55 changes: 44 additions & 11 deletions migrator.go
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Original file line number Diff line number Diff line change
Expand Up @@ -6,24 +6,54 @@ import (
"fmt"
)

const tableName = "migrations"
const defaultTableName = "migrations"

// Migrator is the migrator implementation
type Migrator struct {
tableName string
migrations []interface{}
}

// Option sets options such migrations or table name.
type Option func(*Migrator)

// TableName creates an option to allow overriding the default table name
func TableName(tableName string) Option {
return func(m *Migrator) {
m.tableName = tableName
}
}

// Migrations creates an option with provided migrations
func Migrations(migrations ...interface{}) Option {
return func(m *Migrator) {
m.migrations = migrations
}
}

// New creates a new migrator instance
func New(migrations ...interface{}) (*Migrator, error) {
for _, m := range migrations {
func New(opts ...Option) (*Migrator, error) {
m := &Migrator{
tableName: defaultTableName,
}
for _, opt := range opts {
opt(m)
}

if len(m.migrations) == 0 {
return nil, errors.New("migrator: migrations must be provided")
}

for _, m := range m.migrations {
switch m.(type) {
case *Migration:
case *MigrationNoTx:
default:
return nil, errors.New("migrator: invalid migration type")
}
}
return &Migrator{migrations: migrations}, nil

return m, nil
}

// Migrate applies all available migrations
Expand All @@ -35,13 +65,13 @@ func (m *Migrator) Migrate(db *sql.DB) error {
version VARCHAR(255) NOT NULL,
PRIMARY KEY (id)
);
`, tableName))
`, m.tableName))
if err != nil {
return err
}

// count applied migrations
count, err := countApplied(db)
count, err := countApplied(db, m.tableName)
if err != nil {
return err
}
Expand All @@ -52,7 +82,7 @@ func (m *Migrator) Migrate(db *sql.DB) error {

// plan migrations
for idx, migration := range m.migrations[count:len(m.migrations)] {
insertVersion := fmt.Sprintf("INSERT INTO %s (id, version) VALUES (%d, '%s')", tableName, idx+count, migration.(fmt.Stringer).String())
insertVersion := fmt.Sprintf("INSERT INTO %s (id, version) VALUES (%d, '%s')", m.tableName, idx+count, migration.(fmt.Stringer).String())
switch m := migration.(type) {
case *Migration:
if err := migrate(db, insertVersion, m); err != nil {
Expand All @@ -69,12 +99,15 @@ func (m *Migrator) Migrate(db *sql.DB) error {
}

// Pending returns all pending (not yet applied) migrations
func (m *Migrator) Pending(db *sql.DB) []interface{} {
count, _ := countApplied(db)
return m.migrations[count:len(m.migrations)]
func (m *Migrator) Pending(db *sql.DB) ([]interface{}, error) {
count, err := countApplied(db, m.tableName)
if err != nil {
return nil, err
}
return m.migrations[count:len(m.migrations)], nil
}

func countApplied(db *sql.DB) (int, error) {
func countApplied(db *sql.DB, tableName string) (int, error) {
// count applied migrations
var count int
rows, err := db.Query(fmt.Sprintf("SELECT count(*) FROM %s", tableName))
Expand Down
104 changes: 52 additions & 52 deletions migrator_test.go
View file
Original file line number Diff line number Diff line change
Expand Up @@ -13,43 +13,45 @@ import (
_ "github.com/lib/pq" // postgres driver
)

func migrateTest(driverName, url string) error {
migrator, err := New(
&Migration{
Name: "Using tx, encapsulate two queries",
Func: func(tx *sql.Tx) error {
if _, err := tx.Exec("CREATE TABLE foo (id INT PRIMARY KEY)"); err != nil {
return err
}
if _, err := tx.Exec("INSERT INTO foo (id) VALUES (1)"); err != nil {
return err
}
return nil
},
var migrations = []interface{}{
&Migration{
Name: "Using tx, encapsulate two queries",
Func: func(tx *sql.Tx) error {
if _, err := tx.Exec("CREATE TABLE foo (id INT PRIMARY KEY)"); err != nil {
return err
}
if _, err := tx.Exec("INSERT INTO foo (id) VALUES (1)"); err != nil {
return err
}
return nil
},
&MigrationNoTx{
Name: "Using db, execute one query",
Func: func(db *sql.DB) error {
if _, err := db.Exec("INSERT INTO foo (id) VALUES (2)"); err != nil {
return err
}
return nil
},
},
&MigrationNoTx{
Name: "Using db, execute one query",
Func: func(db *sql.DB) error {
if _, err := db.Exec("INSERT INTO foo (id) VALUES (2)"); err != nil {
return err
}
return nil
},
&Migration{
Name: "Using tx, one embedded query",
Func: func(tx *sql.Tx) error {
query, err := _escFSString(false, "/testdata/0_bar.sql")
if err != nil {
return err
}
if _, err := tx.Exec(query); err != nil {
return err
}
return nil
},
},
&Migration{
Name: "Using tx, one embedded query",
Func: func(tx *sql.Tx) error {
query, err := _escFSString(false, "/testdata/0_bar.sql")
if err != nil {
return err
}
if _, err := tx.Exec(query); err != nil {
return err
}
return nil
},
)
},
}

func migrateTest(driverName, url string) error {
migrator, err := New(Migrations(migrations...))
if err != nil {
return err
}
Expand Down Expand Up @@ -89,7 +91,7 @@ func TestMigrationNumber(t *testing.T) {
if err != nil {
t.Fatal(err)
}
count, err := countApplied(db)
count, err := countApplied(db, defaultTableName)
if err != nil {
t.Fatal(err)
}
Expand All @@ -99,7 +101,7 @@ func TestMigrationNumber(t *testing.T) {
}

func TestDatabaseNotFound(t *testing.T) {
migrator, err := New(&Migration{})
migrator, err := New(Migrations(&Migration{}))
if err != nil {
t.Fatal(err)
}
Expand All @@ -114,7 +116,7 @@ func TestBadMigrations(t *testing.T) {
if err != nil {
t.Fatal(err)
}
_, err = db.Exec(fmt.Sprintf("DROP TABLE IF EXISTS %s", tableName))
_, err = db.Exec(fmt.Sprintf("DROP TABLE IF EXISTS %s", defaultTableName))
if err != nil {
t.Fatal(err)
}
Expand All @@ -126,27 +128,27 @@ func TestBadMigrations(t *testing.T) {
}{
{
name: "bad tx migration",
input: mustMigrator(New(&Migration{
input: mustMigrator(New(Migrations(&Migration{
Name: "bad tx migration",
Func: func(tx *sql.Tx) error {
if _, err := tx.Exec("FAIL FAST"); err != nil {
return err
}
return nil
},
})),
}))),
},
{
name: "bad db migration",
input: mustMigrator(New(&MigrationNoTx{
input: mustMigrator(New(Migrations(&MigrationNoTx{
Name: "bad db migration",
Func: func(db *sql.DB) error {
if _, err := db.Exec("FAIL FAST"); err != nil {
return err
}
return nil
},
})),
}))),
},
}

Expand Down Expand Up @@ -189,7 +191,7 @@ func TestBadMigrationNumber(t *testing.T) {
if err != nil {
t.Fatal(err)
}
migrator := mustMigrator(New(
migrator := mustMigrator(New(Migrations(
&Migration{
Name: "bad migration number",
Func: func(tx *sql.Tx) error {
Expand All @@ -199,7 +201,7 @@ func TestBadMigrationNumber(t *testing.T) {
return nil
},
},
))
)))
if err := migrator.Migrate(db); err == nil {
t.Fatalf("BAD MIGRATION NUMBER should fail: %v", err)
}
Expand All @@ -210,12 +212,7 @@ func TestPending(t *testing.T) {
if err != nil {
t.Fatal(err)
}
migrator, _ := New()
pending := migrator.Pending(db)
if len(pending) != 0 {
t.Fatalf("pending migrations should be 0")
}
migrator = mustMigrator(New(
migrator := mustMigrator(New(Migrations(
&Migration{
Name: "Using tx, create baz table",
Func: func(tx *sql.Tx) error {
Expand All @@ -225,9 +222,12 @@ func TestPending(t *testing.T) {
return nil
},
},
))
pending = migrator.Pending(db)
)))
pending, err := migrator.Pending(db)
if err != nil {
t.Fatal(err)
}
if len(pending) != 1 {
t.Fatalf("pending migrations should be 1")
t.Fatalf("pending migrations should be 1, got %d", len(pending))
}
}

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