Flatten package layout

postgres.go

@@ -0,0 +1,128 @@
+package main
+
+import (
+	"database/sql"
+	"fmt"
+	"github.com/lib/pq"
+	"net/url"
+)
+
+// PostgresDriver provides top level database functions
+type PostgresDriver struct {
+}
+
+// Open creates a new database connection
+func (drv PostgresDriver) Open(u *url.URL) (*sql.DB, error) {
+	return sql.Open("postgres", u.String())
+}
+
+func (drv PostgresDriver) openPostgresDB(u *url.URL) (*sql.DB, error) {
+	// connect to postgres database
+	postgresURL := *u
+	postgresURL.Path = "postgres"
+
+	return drv.Open(&postgresURL)
+}
+
+// CreateDatabase creates the specified database
+func (drv PostgresDriver) CreateDatabase(u *url.URL) error {
+	name := 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 PostgresDriver) DropDatabase(u *url.URL) error {
+	name := 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 PostgresDriver) DatabaseExists(u *url.URL) (bool, error) {
+	name := 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 PostgresDriver) 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 PostgresDriver) 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 PostgresDriver) InsertMigration(db Transaction, version string) error {
+	_, err := db.Exec("insert into schema_migrations (version) values ($1)", version)
+
+	return err
+}
+
+// DeleteMigration removes a migration record
+func (drv PostgresDriver) DeleteMigration(db Transaction, version string) error {
+	_, err := db.Exec("delete from schema_migrations where version = $1", version)
+
+	return err
+}