Timothy Messier
79866a287f
This adds the ability to define hooks that will run prior to a schema migration. The hooks should only be used when a migration would fail due to data being in an invalid state, likely due to a bug in the previous schema definition. For example if a column was missing a constraint, and a new migration is attempting to add the constraint, there might already be values that violate the new constraint. In such cases, we would want the user to make a decision to address the data, and need to provide them with details about what data is problematic in case they want to manually address the problem. To help the user, if there is a sane way to address the data, we should provide an option to automatically "repair" the data, allowing the migration to continue. However, this still should be an explicit opt-in from the user, and we need to clearly describe what the repair option would do to the user so they understand the consequences of opting in. To accomplish this each migration can be provided a hook that contains a CheckFunc, RepairFunc, and RepairDescription. These functions must operate at the point-in-time of the migration immediately preceding the current migration, as as such they should not use and domain packages or repositories, instead they should use direct sql with the sql library. The description is used to explain what the RepairFunc will do. Hooks should be defined in `internal/db/schema/migrations/oss/oss.go` and registered with the schema edition. See the example in `internal/db/schema/manager_example_test.go` for more details.
db package
Usage
Just some high-level usage highlights to get you started. Read the godocs for a complete list of capabilities and their documentation.
dialect = postgres.New(postgres.Config{
DSN: connectionUrl},
)
conn, _ := gorm.Open(dialect, &gorm.Config{})
// Db implements both the Reader and Writer interfaces
rw := Db{Tx: conn}
// There are writer methods like: Create, Update and Delete
// that will write Gorm struct to the db. These writer methods
// all support options for writing Oplog entries for the
// caller: WithOplog(yourWrapper, yourMetadata)
// the caller is responsible for the transaction life cycle of the writer
// and if an error is returned the caller must decide what to do with
// the transaction, which is almost always a rollback for the caller.
err = rw.Create(context.Background(), user)
// There are reader methods like: LookupByPublicId,
// LookupByName, SearchBy, LookupBy, etc
// which will lookup resources for you and scan them into your Gorm struct
err = rw.LookupByPublicId(context.Background(), foundUser)
// There's reader ScanRows that facilitates scanning rows from
// a query into your Gorm struct
where := "select * from test_users where name in ($1, $2)"
rows, err := rw.Query(context.Background(), where, []interface{}{"alice", "bob"})
defer rows.Close()
for rows.Next() {
user := db_test.NewTestUser()
// scan the row into your Gorm struct
if err := rw.ScanRows(rows, &user); err != nil {
return err
}
// Do something with the Gorm user struct
}
// DoTx is a writer function that wraps a TxHandler
// in a retryable transaction. You simply implement a
// TxHandler that does your writes and hand the handler
// to DoTx, which will wrap the writes in a retryable
// transaction with the retry attempts and backoff
// strategy you specify via options.
_, err = w.DoTx(
context.Background(),
10, // ten retries
ExpBackoff{}, // exponential backoff
func(w Writer) error {
// the TxHandler updates the user's friendly name
return w.Update(context.Background(), user, []string{"FriendlyName"},
// write oplogs for this update
WithOplog(
InitTestWrapper(t),
oplog.Metadata{
"key-only": nil,
"deployment": []string{"amex"},
"project": []string{"central-info-systems", "local-info-systems"},
},
),
)
})