README
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Migrations
Database migrations are handled by this package. All migrations should be created in separate files, following a starndard naming convetion
The migrations.go file defines an array of migrate functions that are called by the gormigrate helper. Each migration function should perform a specific migration.
Creating a new migration
Create a migration ID based on the time using the YYYYMMDDHHMM format. Example: August 21 2018 at 2:54pm would be 201808211454.
Your migration's name should be used in the file name and in the function name and should adequately represent the actions your migration is taking. If your migration is doing too much to fit in a name, you should consider creating multiple migrations.
Create a separate file in pkg/db/ following the naming schema in place: <migration_id>_<migration_name>.go. In the file, you'll create a function that returns a gormmigrate.Migration object with gormigrate.Migrate and gormigrate.Rollback functions defined.
Add the function you created in the separate file to the migrations list in pkg/db/migrations.go.
If necessary, write a test to verify the migration. See test/integration/migrations_test.go for examples.
Migration Rules
Migration IDs
Each migration has an ID that defines the order in which the migration is run.
IDs are numerical timestamps that must sort ascending. Use YYYYMMDDHHMM w/ 24 hour time for format.
Example: August 21 2018 at 2:54pm would be 201808211454.
Migration IDs must be descending. If you create a migration, submit an MR, and another MR is merged before yours is able to be merged, you must update the ID to represent a date later than any previous migration.
Models in Migrations
Represent modesl inline with migrations to represent the evolution of the object over time.
For example, it is necessary to add a boolean field "hidden" to the "Account" model. This is how you would represent the account model in that migration:
type Account struct {
Model
Username string
FirstName string
LastName string
Hidden boolean
}
err := tx.AutoMigrate(&Account{}).Error
if err != nil {
...
DO NOT IMPORT THE API PKG. When a migration imports the api pkg and uses models defined in it, the migration may work the first time it is run. The models in pkg/api are bound to change as the project grows. Eventually, the models could change so that the migration breaks, causing any new deployments to fail on your old shitty migration.
Record Deletions
If it is necessary to delete a record in a migration, be aware of a couple caveats around deleting wth gorm:
-
You must pass a record with an ID to
gorm.Delete(&record), otherwise ALL RECORDS WILL BE DELETED -
Gorm soft deletes by default. This means it sets the
deleted_atfield to a non-null value and any subsequent gorm calls will ignore it. If you are deleting a record that needs to be permanently deleted (like permissions), usegorm.Unscoped().Delete.
See the gorm documentation around deletions for more information
Migration tests
In most cases, it shouldn't be necessary to create a test for a migration. However, if the migration is manipulating records and poses a significant risk of completely borking up important data, a test should be written.
Tests are difficult to write for migrations and are likely to fail one day long after the migration has already run in production. After a migration is run in production, it is safe to delete the test from the integration test suite.
The test helper has a couple helpful functions for testing migrations. You can use h.CleanDB() to completely wipe the database clean, then h.MigrateTo(<migration_id>) to migrate to a specific migration ID. You should then be able to create whatever records in the database you need to test against and finally run h.MigrateDB() to run your created migration and all subsequent migrations.
Documentation
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Index ¶
- func ArgsToOrderBy(orderByArgs []string, disallowedFields map[string]string) (orderBy []string, err *errors.ServiceError)
- func FieldNameWalk(n tsl.Node, disallowedFields map[string]string) (newNode tsl.Node, err *errors.ServiceError)
- func GetTableName(g2 *gorm.DB) string
- func MarkForRollback(ctx context.Context, err error)
- func Migrate(g2 *gorm.DB) error
- func MigrateTo(sessionFactory SessionFactory, migrationID string)
- func NewContext(ctx context.Context, connection SessionFactory) (context.Context, error)
- func RegisterAdvisoryLockMetrics()
- func ResetAdvisoryLockMetricsCollectors()
- func Resolve(ctx context.Context)
- func TransactionMiddleware(next http.Handler, connection SessionFactory) http.Handler
- func UnregisterAdvisoryLockMetrics()
- func UpdateAdvisoryLockCountMetric(lockType LockType, status string)
- func UpdateAdvisoryLockDurationMetric(lockType LockType, status string, startTime time.Time)
- type AdvisoryLock
- type AdvisoryLockFactory
- func (f *AdvisoryLockFactory) NewAdvisoryLock(ctx context.Context, id string, lockType LockType) (string, error)
- func (f *AdvisoryLockFactory) NewNonBlockingLock(ctx context.Context, id string, lockType LockType) (string, bool, error)
- func (f *AdvisoryLockFactory) Unlock(ctx context.Context, uuid string)
- type AdvisoryLockStore
- type LockFactory
- type LockType
- type MetricsCollector
- type SessionFactory
- type StringMap
Constants ¶
This section is empty.
Variables ¶
This section is empty.
Functions ¶
func ArgsToOrderBy ¶
func ArgsToOrderBy( orderByArgs []string, disallowedFields map[string]string) (orderBy []string, err *errors.ServiceError)
ArgsToOrderBy returns cleaned orderBy list.
func FieldNameWalk ¶
func FieldNameWalk( n tsl.Node, disallowedFields map[string]string) (newNode tsl.Node, err *errors.ServiceError)
FieldNameWalk walks on the filter tree and check/replace the search fields names: a. the the field name is valid. b. replace the field name with the SQL column name.
func GetTableName ¶
func MarkForRollback ¶
MarkForRollback flags the transaction stored in the context for rollback and logs whatever error caused the rollback
func MigrateTo ¶
func MigrateTo(sessionFactory SessionFactory, migrationID string)
MigrateTo a specific migration will not seed the database, seeds are up to date with the latest schema based on the most recent migration This should be for testing purposes mainly
func NewContext ¶
NewContext returns a new context with transaction stored in it. Upon error, the original context is still returned along with an error
func ResetAdvisoryLockMetricsCollectors ¶
func ResetAdvisoryLockMetricsCollectors()
ResetAdvisoryLockMetricsCollectors resets all collectors
func TransactionMiddleware ¶
func TransactionMiddleware(next http.Handler, connection SessionFactory) http.Handler
TransactionMiddleware creates a new HTTP middleware that begins a database transaction and stores it in the request context.
Types ¶
type AdvisoryLock ¶
type AdvisoryLock struct {
// contains filtered or unexported fields
}
AdvisoryLock represents a postgres advisory lock
begin # start a Tx select pg_advisory_xact_lock(id, lockType) # obtain the lock (blocking) end # end the Tx and release the lock
UUID is a way to own the lock. Only the very first service call that owns the lock will have the correct UUID. This is necessary to allow functions to call other service functions as part of the same lock (id, lockType).
type AdvisoryLockFactory ¶
type AdvisoryLockFactory struct {
// contains filtered or unexported fields
}
func NewAdvisoryLockFactory ¶
func NewAdvisoryLockFactory(connection SessionFactory) *AdvisoryLockFactory
NewAdvisoryLockFactory returns a new factory with AdvisoryLock stored in it.
func (*AdvisoryLockFactory) NewAdvisoryLock ¶
func (*AdvisoryLockFactory) NewNonBlockingLock ¶
type AdvisoryLockStore ¶
type AdvisoryLockStore struct {
// contains filtered or unexported fields
}
AdvisoryLockStore is a thread-safe map that stores AdvisoryLocks. Map access is unsafe only when updates are occurring. As long as all goroutines are only reading—looking up elements in the map, including iterating through it using a for range loop and not changing the map by assigning to elements or doing deletions, it is safe for them to access the map concurrently without synchronization.
func NewAdvisoryLockStore ¶
func NewAdvisoryLockStore() *AdvisoryLockStore
NewAdvisoryLockStore returns a new AdvisoryLockStore.
type LockFactory ¶
type LockFactory interface {
// NewAdvisoryLock constructs a new AdvisoryLock that is a blocking PostgreSQL advisory lock
// defined by (id, lockType) and returns a UUID as this AdvisoryLock owner id.
NewAdvisoryLock(ctx context.Context, id string, lockType LockType) (string, error)
// NewNonBlockingLock constructs a new nonblocking AdvisoryLock defined by (id, lockType),
// returns a UUID and a boolean on whether the lock is acquired.
NewNonBlockingLock(ctx context.Context, id string, lockType LockType) (string, bool, error)
// Unlock unlocks one AdvisoryLock by its owner id.
Unlock(ctx context.Context, uuid string)
}
LockFactory provides the blocking/unblocking locks based on PostgreSQL advisory lock.
type MetricsCollector ¶
type MetricsCollector interface {
}
type SessionFactory ¶
type StringMap ¶
similar to gorms datatypes.JSONMap but it restricts the values to strings
func EmptyMapToNilStringMap ¶
Source Files
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Directories
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| Path | Synopsis |
|---|---|
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Package db_context dbContext provides a wrapper around db context handling to allow access to the db context without requiring importing the db package, thus avoiding cyclic imports
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Package db_context dbContext provides a wrapper around db context handling to allow access to the db context without requiring importing the db package, thus avoiding cyclic imports |