forked from mattes/migrate
/
driver.go
72 lines (63 loc) · 2.01 KB
/
driver.go
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// Package driver holds the driver interface.
package driver
import (
"errors"
"fmt"
"github.com/mattes/migrate/driver/bash"
"github.com/mattes/migrate/driver/postgres"
"github.com/mattes/migrate/file"
neturl "net/url" // alias to allow `url string` func signature in New
)
// Driver is the interface type that needs to implemented by all drivers.
type Driver interface {
// Initialize is the first function to be called.
// Check the url string and open and verify any connection
// that has to be made.
Initialize(url string) error
// FilenameExtension returns the extension of the migration files.
// The returned string must not begin with a dot.
FilenameExtension() string
// Migrate is the heart of the driver.
// It will receive a file which the driver should apply
// to its backend or whatever. The migration function should use
// the pipe channel to return any errors or other useful information.
Migrate(file file.File, pipe chan interface{})
// Version returns the current migration version.
Version() (uint64, error)
}
// New returns Driver and calls Initialize on it
func New(url string) (Driver, error) {
u, err := neturl.Parse(url)
if err != nil {
return nil, err
}
switch u.Scheme {
case "postgres":
d := &postgres.Driver{}
verifyFilenameExtension("postgres", d)
if err := d.Initialize(url); err != nil {
return nil, err
}
return d, nil
case "bash":
d := &bash.Driver{}
verifyFilenameExtension("bash", d)
if err := d.Initialize(url); err != nil {
return nil, err
}
return d, nil
default:
return nil, errors.New(fmt.Sprintf("Driver '%s' not found.", u.Scheme))
}
}
// verifyFilenameExtension panics if the drivers filename extension
// is not correct or empty.
func verifyFilenameExtension(driverName string, d Driver) {
f := d.FilenameExtension()
if f == "" {
panic(fmt.Sprintf("%s.FilenameExtension() returns empty string.", driverName))
}
if f[0:1] == "." {
panic(fmt.Sprintf("%s.FilenameExtension() returned string must not start with a dot.", driverName))
}
}