| Safe Haskell | None |
|---|---|
| Language | Haskell2010 |
Database.Schema.Migrations.Store
Description
This module provides an abstraction for a migration store, a
facility in which Migrations can be stored and from which they
can be loaded. This module also provides functions for taking
Migrations from a store and converting them into the appropriate
intermediate types for use with the rest of this library.
Synopsis
- data MigrationStore = MigrationStore {
- loadMigration :: Text -> IO (Either String Migration)
- saveMigration :: Migration -> IO ()
- getMigrations :: IO [Text]
- fullMigrationName :: Text -> IO FilePath
- data MapValidationError
- data StoreData = StoreData {}
- type MigrationMap = Map Text Migration
- loadMigrations :: MigrationStore -> IO (Either [MapValidationError] StoreData)
- storeMigrations :: StoreData -> [Migration]
- storeLookup :: StoreData -> Text -> Maybe Migration
- depGraphFromMapping :: MigrationMap -> Either String (DependencyGraph Migration)
- validateMigrationMap :: MigrationMap -> [MapValidationError]
- validateSingleMigration :: MigrationMap -> Migration -> [MapValidationError]
- leafMigrations :: StoreData -> [Text]
Documentation
data MigrationStore Source #
The type of migration storage facilities. A MigrationStore is a facility in which new migrations can be created, and from which existing migrations can be loaded.
Constructors
| MigrationStore | |
Fields
| |
data MapValidationError Source #
A type for types of validation errors for migration maps.
Constructors
| DependencyReferenceError Text Text | A migration claims a dependency on a migration that does not exist. |
| DependencyGraphError String | An error was encountered when constructing the dependency graph for this store. |
| InvalidMigration String | The specified migration is invalid. |
Instances
| Eq MapValidationError Source # | |
Defined in Database.Schema.Migrations.Store Methods (==) :: MapValidationError -> MapValidationError -> Bool # (/=) :: MapValidationError -> MapValidationError -> Bool # | |
| Show MapValidationError Source # | |
Defined in Database.Schema.Migrations.Store Methods showsPrec :: Int -> MapValidationError -> ShowS # show :: MapValidationError -> String # showList :: [MapValidationError] -> ShowS # | |
Constructors
| StoreData | |
High-level Store API
loadMigrations :: MigrationStore -> IO (Either [MapValidationError] StoreData) Source #
Load migrations from the specified MigrationStore, validate the
loaded migrations, and return errors or a MigrationMap on
success. Generally speaking, this will be the first thing you
should call once you have constructed a MigrationStore.
storeMigrations :: StoreData -> [Migration] Source #
Miscellaneous Functions
depGraphFromMapping :: MigrationMap -> Either String (DependencyGraph Migration) Source #
Create a DependencyGraph from a MigrationMap; returns Left if
the dependency graph cannot be constructed (e.g., due to a
dependency cycle) or Right on success. Generally speaking, you
won't want to use this directly; use loadMigrations instead.
validateMigrationMap :: MigrationMap -> [MapValidationError] Source #
Validate a migration map. Returns zero or more validation errors.
validateSingleMigration :: MigrationMap -> Migration -> [MapValidationError] Source #
Validate a single migration. Looks up the migration's
dependencies in the specified MigrationMap and returns a
MapValidationError for each one that does not exist in the map.
leafMigrations :: StoreData -> [Text] Source #
Finds migrations that no other migration depends on (effectively finds all vertices with in-degree equal to zero).