Documentation ¶
Overview ¶
Package database provides the Driver interface. All database drivers must implement this interface, register themselves, optionally provide a `WithInstance` function and pass the tests in package database/testing.
Index ¶
Examples ¶
Constants ¶
View Source
const NilVersion int = -1
Variables ¶
Functions ¶
func CasRestoreOnErr ¶
CasRestoreOnErr CAS wrapper to automatically restore the lock state on error
func GenerateAdvisoryLockId ¶
GenerateAdvisoryLockId inspired by rails migrations, see https://goo.gl/8o9bCT
Types ¶
type Driver ¶
type Driver interface { // Open returns a new driver instance configured with parameters // coming from the URL string. Migrate will call this function // only once per instance. Open(url string) (Driver, error) SetSourceDriver(sourceDrv source.Driver) error // Close closes the underlying database instance managed by the driver. // Migrate will call this function only once per instance. Close() error // Lock should acquire a database lock so that only one migration process // can run at a time. Migrate will call this function before Run is called. // If the implementation can't provide this functionality, return nil. // Return database.ErrLocked if database is already locked. Lock() error // Unlock should release the lock. Migrate will call this function after // all migrations have been run. Unlock() error // Run applies a migration to the database. migration is guaranteed to be not nil. Run(migration io.Reader) error // SetVersion saves version and dirty state. // Migrate will call this function before and after each call to Run. // version must be >= -1. -1 means NilVersion. // // forced // forced flag indicates that this is a forced migration. // // knownDirection // If knownDirection is not provided, direction will be estimated // based on comparing the given version with the last applied version. SetVersion(version int, dirty bool, forced bool, knownDirection *source.Direction) (*source.Direction, error) // Version returns the currently active version and if the database is dirty. // When no migration has been applied, it must return version -1. // Dirty means, a previous migration failed and user interaction is required. Version() (version int, dirty bool, err error) // ListAppliedVersions returns a list of all versions that are known // to be applied to the database. This will not include versions that // were applied before history tracking was enabled. // Versions that were applied but "reverted" by down migrations will // not be included until up migrations are re-run to restore them. ListAppliedVersions() ([]int, error) // Drop deletes everything in the database. // Note that this is a breaking action, a new call to Open() is necessary to // ensure subsequent calls work as expected. Drop() error }
Driver is the interface every database driver must implement.
How to implement a database driver?
- Implement this interface.
- Optionally, add a function named `WithInstance`. This function should accept an existing DB instance and a Config{} struct and return a driver instance.
- Add a test that calls database/testing.go:Test()
- Add own tests for Open(), WithInstance() (when provided) and Close(). All other functions are tested by tests in database/testing. Saves you some time and makes sure all database drivers behave the same way.
- Call Register in init().
- Create a internal/cli/build_<driver-name>.go file
- Add driver name in 'DATABASE' variable in Makefile
Guidelines:
- Don't try to correct user input. Don't assume things. When in doubt, return an error and explain the situation to the user.
- All configuration input must come from the URL string in func Open() or the Config{} struct in WithInstance. Don't os.Getenv().
Example ¶
// see database/stub for an example // database/stub/stub.go has the driver implementation // database/stub/stub_test.go runs database/testing/test.go:Test
Output:
type Error ¶
type Error struct { // Optional: the line number Line uint // Query is a query excerpt Query []byte // Err is a useful/helping error message for humans Err string // OrigErr is the underlying error OrigErr error }
Error should be used for errors involving queries ran against the database
Directories ¶
Path | Synopsis |
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Package multistmt provides methods for parsing multi-statement database migrations
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Package multistmt provides methods for parsing multi-statement database migrations |
Package testing has the database tests.
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Package testing has the database tests. |
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