dbmate/driver/postgres/postgres.go
2015-12-01 00:44:12 -08:00

136 lines
3 KiB
Go

package postgres
import (
"database/sql"
"fmt"
"github.com/adrianmacneil/dbmate/driver/shared"
"github.com/lib/pq"
"io"
"net/url"
)
// Driver provides top level database functions
type Driver struct {
}
// Open creates a new database connection
func (drv Driver) Open(u *url.URL) (*sql.DB, error) {
return sql.Open("postgres", u.String())
}
func (drv Driver) openPostgresDB(u *url.URL) (*sql.DB, error) {
// connect to postgres database
postgresURL := *u
postgresURL.Path = "postgres"
return drv.Open(&postgresURL)
}
func mustClose(c io.Closer) {
if err := c.Close(); err != nil {
panic(err)
}
}
// CreateDatabase creates the specified database
func (drv Driver) CreateDatabase(u *url.URL) error {
name := shared.DatabaseName(u)
fmt.Printf("Creating: %s\n", name)
db, err := drv.openPostgresDB(u)
if err != nil {
return err
}
defer mustClose(db)
_, err = db.Exec(fmt.Sprintf("create database %s",
pq.QuoteIdentifier(name)))
return err
}
// DropDatabase drops the specified database (if it exists)
func (drv Driver) DropDatabase(u *url.URL) error {
name := shared.DatabaseName(u)
fmt.Printf("Dropping: %s\n", name)
db, err := drv.openPostgresDB(u)
if err != nil {
return err
}
defer mustClose(db)
_, err = db.Exec(fmt.Sprintf("drop database if exists %s",
pq.QuoteIdentifier(name)))
return err
}
// DatabaseExists determines whether the database exists
func (drv Driver) DatabaseExists(u *url.URL) (bool, error) {
name := shared.DatabaseName(u)
db, err := drv.openPostgresDB(u)
if err != nil {
return false, err
}
defer mustClose(db)
exists := false
err = db.QueryRow("select true from pg_database where datname = $1", name).
Scan(&exists)
if err == sql.ErrNoRows {
return false, nil
}
return exists, err
}
// CreateMigrationsTable creates the schema_migrations table
func (drv Driver) CreateMigrationsTable(db *sql.DB) error {
_, err := db.Exec(`create table if not exists schema_migrations (
version varchar(255) primary key)`)
return err
}
// SelectMigrations returns a list of applied migrations
// with an optional limit (in descending order)
func (drv Driver) SelectMigrations(db *sql.DB, limit int) (map[string]bool, error) {
query := "select version from schema_migrations order by version desc"
if limit >= 0 {
query = fmt.Sprintf("%s limit %d", query, limit)
}
rows, err := db.Query(query)
if err != nil {
return nil, err
}
defer mustClose(rows)
migrations := map[string]bool{}
for rows.Next() {
var version string
if err := rows.Scan(&version); err != nil {
return nil, err
}
migrations[version] = true
}
return migrations, nil
}
// InsertMigration adds a new migration record
func (drv Driver) InsertMigration(db shared.Transaction, version string) error {
_, err := db.Exec("insert into schema_migrations (version) values ($1)", version)
return err
}
// DeleteMigration removes a migration record
func (drv Driver) DeleteMigration(db shared.Transaction, version string) error {
_, err := db.Exec("delete from schema_migrations where version = $1", version)
return err
}