Database.Beam.Migrate.Types

Checked database entities

type CheckedDatabaseSettings be db = db (CheckedDatabaseEntity be db)

The type of a checked database descriptor. Conceptually, this is just a DatabaseSettings with a set of predicates. Use unCheckDatabase to get the regular DatabaseSettings object and collectChecks to access the predicates.

class IsDatabaseEntity be entity => IsCheckedDatabaseEntity be entity where

Like IsDatabaseEntity in beam-core, but for entities against which we can generate DatabasePredicates. Conceptually, this is the same as IsDatabaseEntity, but with one extra function to generate DatabasePredicates from the description.

Minimal complete definition

unCheck, collectEntityChecks, checkedDbEntityAuto

Associated Types

data CheckedDatabaseEntityDescriptor be entity :: *

The type of the descriptor for this checked entity. Usually this wraps the corresponding DatabaseEntityDescriptor from IsDatabaseEntity, along with some mechanism for generating DatabasePredicates.

type CheckedDatabaseEntityDefaultRequirements be entity syntax :: Constraint

Like DatabaseEntityDefaultRequirements but for checked entities

Methods

unCheck :: CheckedDatabaseEntityDescriptor be entity -> DatabaseEntityDescriptor be entity

Produce the corresponding DatabaseEntityDescriptior

collectEntityChecks :: CheckedDatabaseEntityDescriptor be entity -> [SomeDatabasePredicate]

Produce the set of DatabasePredicates that apply to this entity

checkedDbEntityAuto :: CheckedDatabaseEntityDefaultRequirements be entity syntax => Proxy syntax -> Text -> CheckedDatabaseEntityDescriptor be entity

Like dbEntityAuto but for checked databases. Most often, this wraps dbEntityAuto and provides some means to generate DatabasePredicates

Instances

Beamable tbl => IsCheckedDatabaseEntity be (TableEntity tbl)

Defined in Database.Beam.Migrate.Types.CheckedEntities

Associated Types

data CheckedDatabaseEntityDescriptor be (TableEntity tbl) :: *

type CheckedDatabaseEntityDefaultRequirements be (TableEntity tbl) syntax :: Constraint

Methods

unCheck :: CheckedDatabaseEntityDescriptor be (TableEntity tbl) -> DatabaseEntityDescriptor be (TableEntity tbl)

collectEntityChecks :: CheckedDatabaseEntityDescriptor be (TableEntity tbl) -> [SomeDatabasePredicate]

checkedDbEntityAuto :: CheckedDatabaseEntityDefaultRequirements be (TableEntity tbl) syntax => Proxy syntax -> Text -> CheckedDatabaseEntityDescriptor be (TableEntity tbl)

IsCheckedDatabaseEntity be (DomainTypeEntity ty)

Defined in Database.Beam.Migrate.Types.CheckedEntities

Associated Types

data CheckedDatabaseEntityDescriptor be (DomainTypeEntity ty) :: *

type CheckedDatabaseEntityDefaultRequirements be (DomainTypeEntity ty) syntax :: Constraint

Methods

unCheck :: CheckedDatabaseEntityDescriptor be (DomainTypeEntity ty) -> DatabaseEntityDescriptor be (DomainTypeEntity ty)

collectEntityChecks :: CheckedDatabaseEntityDescriptor be (DomainTypeEntity ty) -> [SomeDatabasePredicate]

checkedDbEntityAuto :: CheckedDatabaseEntityDefaultRequirements be (DomainTypeEntity ty) syntax => Proxy syntax -> Text -> CheckedDatabaseEntityDescriptor be (DomainTypeEntity ty)

data CheckedDatabaseEntity be (db :: (* -> *) -> *) entityType where

Like DatabaseEntity but for checked databases

Constructors

CheckedDatabaseEntity :: IsCheckedDatabaseEntity be entityType => CheckedDatabaseEntityDescriptor be entityType -> [SomeDatabasePredicate] -> CheckedDatabaseEntity be db entityType

unCheckDatabase :: forall be db. Database be db => CheckedDatabaseSettings be db -> DatabaseSettings be db

Convert a CheckedDatabaseSettings to a regular DatabaseSettings. The return value is suitable for use in any regular beam query or DML statement.

collectChecks :: forall be db. Database be db => CheckedDatabaseSettings be db -> [SomeDatabasePredicate]

A beam-migrate database schema is defined completely by the set of predicates that apply to it. This function allows you to access this definition for a CheckedDatabaseSettings object.

Modifyinging checked entities

data CheckedFieldModification tbl a

Purposefully opaque type describing how to modify a table field. Used to parameterize the second argument to modifyCheckedTable. For now, the only way to construct a value is the IsString instance, which allows you to rename the field.

Instances

Beamable tbl => RenamableWithRule (tbl (CheckedFieldModification tbl))

Defined in Database.Beam.Migrate.Types.CheckedEntities

Methods

renamingFields :: (Text -> Text) -> tbl (CheckedFieldModification tbl)

IsString (CheckedFieldModification tbl a)

Defined in Database.Beam.Migrate.Types.CheckedEntities

Methods

fromString :: String -> CheckedFieldModification tbl a

checkedFieldNamed :: Text -> CheckedFieldModification tbl a

modifyCheckedTable :: (Text -> Text) -> tbl (CheckedFieldModification tbl) -> EntityModification (CheckedDatabaseEntity be db) be (TableEntity tbl)

Modify a checked table.

The first argument is a function that takes the original table name as input and produces a new table name.

The second argument gives instructions on how to rename each field in the table. Use checkedTableModification to create a value of this type which does no renaming. Each field in the table supplied here has the type CheckedFieldModification. Most commonly, the programmer will use the OverloadedStrings instance to provide a new name.

Examples

Rename a table, without renaming any of its fields:

modifyCheckedTable (_ -> NewTblNm) checkedTableModification

Modify a table, renaming the field called _field1 in Haskell to FirstName. Note that below, FirstName represents a CheckedFieldModification object.

modifyCheckedTable id (checkedTableModification { _field1 = FirstName })

checkedTableModification :: forall tbl. Beamable tbl => tbl (CheckedFieldModification tbl)

Produce a table field modification that does nothing

Most commonly supplied as the second argument to modifyCheckedTable when you just want to rename the table, not the fields.

Predicates

class (Typeable p, Hashable p, Eq p) => DatabasePredicate p where

A predicate is a type that describes some condition that the database schema must meet. Beam represents database schemas as the set of all predicates that apply to a database schema. The Hashable and Eq instances allow us to build HashSets of predicates to represent schemas in this way.

Minimal complete definition

englishDescription, predicateSpecificity, serializePredicate

Methods

englishDescription :: p -> String

An english language description of this predicate. For example, "There is a table named TableName"

predicateSpecificity :: proxy p -> PredicateSpecificity

Whether or not this predicate applies to all backends or only one backend. This is used when attempting to translate schemas between backends. If you are unsure, provide PredicateSpecificityOnlyBackend along with an identifier unique to your backend.

serializePredicate :: p -> Value

Serialize a predicate to a JSON Value.

predicateCascadesDropOn :: DatabasePredicate p' => p -> p' -> Bool

Some predicates require other predicates to be true. For example, in order for a table to have a column, that table must exist. This function takes in the current predicate and another arbitrary database predicate. It should return True if this predicate needs the other predicate to be true in order to exist.

By default, this simply returns False, which makes sense for many predicates.

Instances

DatabasePredicate TableHasPrimaryKey

Defined in Database.Beam.Migrate.Checks

Methods

englishDescription :: TableHasPrimaryKey -> String

predicateSpecificity :: proxy TableHasPrimaryKey -> PredicateSpecificity

serializePredicate :: TableHasPrimaryKey -> Value

predicateCascadesDropOn :: DatabasePredicate p' => TableHasPrimaryKey -> p' -> Bool

DatabasePredicate TableExistsPredicate

Defined in Database.Beam.Migrate.Checks

Methods

englishDescription :: TableExistsPredicate -> String

predicateSpecificity :: proxy TableExistsPredicate -> PredicateSpecificity

serializePredicate :: TableExistsPredicate -> Value

predicateCascadesDropOn :: DatabasePredicate p' => TableExistsPredicate -> p' -> Bool

(Typeable syntax, Sql92SerializableConstraintDefinitionSyntax (Sql92ColumnSchemaColumnConstraintDefinitionSyntax syntax), Hashable (Sql92ColumnSchemaColumnConstraintDefinitionSyntax syntax), Sql92DisplaySyntax (Sql92ColumnSchemaColumnConstraintDefinitionSyntax syntax), Eq (Sql92ColumnSchemaColumnConstraintDefinitionSyntax syntax)) => DatabasePredicate (TableColumnHasConstraint syntax)

Defined in Database.Beam.Migrate.Checks

Methods

englishDescription :: TableColumnHasConstraint syntax -> String

predicateSpecificity :: proxy (TableColumnHasConstraint syntax) -> PredicateSpecificity

serializePredicate :: TableColumnHasConstraint syntax -> Value

predicateCascadesDropOn :: DatabasePredicate p' => TableColumnHasConstraint syntax -> p' -> Bool

(Typeable syntax, Sql92SerializableDataTypeSyntax (Sql92ColumnSchemaColumnTypeSyntax syntax), Hashable (Sql92ColumnSchemaColumnTypeSyntax syntax), Sql92DisplaySyntax (Sql92ColumnSchemaColumnTypeSyntax syntax), Eq (Sql92ColumnSchemaColumnTypeSyntax syntax)) => DatabasePredicate (TableHasColumn syntax)

Defined in Database.Beam.Migrate.Checks

Methods

englishDescription :: TableHasColumn syntax -> String

predicateSpecificity :: proxy (TableHasColumn syntax) -> PredicateSpecificity

serializePredicate :: TableHasColumn syntax -> Value

predicateCascadesDropOn :: DatabasePredicate p' => TableHasColumn syntax -> p' -> Bool

data SomeDatabasePredicate where

A Database predicate is a value of any type which satisfies DatabasePredicate. We often want to store these in lists and sets, so we need a monomorphic container that can store these polymorphic values.

Constructors

SomeDatabasePredicate :: DatabasePredicate p => p -> SomeDatabasePredicate

Instances

Eq SomeDatabasePredicate

Defined in Database.Beam.Migrate.Types.Predicates

Methods

(==) :: SomeDatabasePredicate -> SomeDatabasePredicate -> Bool

(/=) :: SomeDatabasePredicate -> SomeDatabasePredicate -> Bool

Show SomeDatabasePredicate

Defined in Database.Beam.Migrate.Types.Predicates

Methods

showsPrec :: Int -> SomeDatabasePredicate -> ShowS

show :: SomeDatabasePredicate -> String

showList :: [SomeDatabasePredicate] -> ShowS

Hashable SomeDatabasePredicate

Defined in Database.Beam.Migrate.Types.Predicates

Methods

hashWithSalt :: Int -> SomeDatabasePredicate -> Int

hash :: SomeDatabasePredicate -> Int

NFData SomeDatabasePredicate

Defined in Database.Beam.Migrate.Types.Predicates

Methods

rnf :: SomeDatabasePredicate -> ()

data PredicateSpecificity

Some predicates make sense in any backend. Others only make sense in one. This denotes the difference.

Constructors

PredicateSpecificityOnlyBackend String

PredicateSpecificityAllBackends

Instances

Eq PredicateSpecificity

Defined in Database.Beam.Migrate.Types.Predicates

Methods

(==) :: PredicateSpecificity -> PredicateSpecificity -> Bool

(/=) :: PredicateSpecificity -> PredicateSpecificity -> Bool

Show PredicateSpecificity

Defined in Database.Beam.Migrate.Types.Predicates

Methods

showsPrec :: Int -> PredicateSpecificity -> ShowS

show :: PredicateSpecificity -> String

showList :: [PredicateSpecificity] -> ShowS

Generic PredicateSpecificity

Defined in Database.Beam.Migrate.Types.Predicates

Associated Types

type Rep PredicateSpecificity :: * -> *

Methods

from :: PredicateSpecificity -> Rep PredicateSpecificity x

to :: Rep PredicateSpecificity x -> PredicateSpecificity

Hashable PredicateSpecificity

Defined in Database.Beam.Migrate.Types.Predicates

Methods

hashWithSalt :: Int -> PredicateSpecificity -> Int

hash :: PredicateSpecificity -> Int

ToJSON PredicateSpecificity

Defined in Database.Beam.Migrate.Types.Predicates

Methods

toJSON :: PredicateSpecificity -> Value

toEncoding :: PredicateSpecificity -> Encoding

toJSONList :: [PredicateSpecificity] -> Value

toEncodingList :: [PredicateSpecificity] -> Encoding

FromJSON PredicateSpecificity

Defined in Database.Beam.Migrate.Types.Predicates

Methods

parseJSON :: Value -> Parser PredicateSpecificity

parseJSONList :: Value -> Parser [PredicateSpecificity]

type Rep PredicateSpecificity

Defined in Database.Beam.Migrate.Types.Predicates

type Rep PredicateSpecificity = D1 (MetaData "PredicateSpecificity" "Database.Beam.Migrate.Types.Predicates" "beam-migrate-0.3.2.1-5uUjtiBqfLqFuBaaiGZEEb" False) (C1 (MetaCons "PredicateSpecificityOnlyBackend" PrefixI False) (S1 (MetaSel (Nothing :: Maybe Symbol) NoSourceUnpackedness NoSourceStrictness DecidedLazy) (Rec0 String)) :+: C1 (MetaCons "PredicateSpecificityAllBackends" PrefixI False) (U1 :: * -> *))

p :: DatabasePredicate p => p -> SomeDatabasePredicate

Convenience synonym for SomeDatabasePredicate

Entity checks

newtype TableCheck

A predicate that depends on the name of a table as well as its fields

Constructors

TableCheck (forall tbl. Table tbl => Text -> tbl (TableField tbl) -> SomeDatabasePredicate)

newtype DomainCheck

A predicate that depends on the name of a domain type

Constructors

DomainCheck (Text -> SomeDatabasePredicate)

newtype FieldCheck

A predicate that depedns on the name of a table and one of its fields

Constructors

FieldCheck (Text -> Text -> SomeDatabasePredicate)

Migrations

data MigrationStep syntax next where

Represents a particular step in a migration

Constructors

MigrationStep :: Text -> Migration syntax a -> (a -> next) -> MigrationStep syntax next

Instances

Functor (MigrationStep syntax)

Defined in Database.Beam.Migrate.Types

Methods

fmap :: (a -> b) -> MigrationStep syntax a -> MigrationStep syntax b

(<$) :: a -> MigrationStep syntax b -> MigrationStep syntax a

newtype MigrationSteps syntax from to

A series of MigrationSteps that take a database from the schema in from to the one in to. Use the migrationStep function and the arrow interface to sequence MigrationSteps.

Constructors

MigrationSteps (Kleisli (F (MigrationStep syntax)) from to)

Instances

Arrow (MigrationSteps syntax)

Defined in Database.Beam.Migrate.Types

Methods

arr :: (b -> c) -> MigrationSteps syntax b c

first :: MigrationSteps syntax b c -> MigrationSteps syntax (b, d) (c, d)

second :: MigrationSteps syntax b c -> MigrationSteps syntax (d, b) (d, c)

(***) :: MigrationSteps syntax b c -> MigrationSteps syntax b' c' -> MigrationSteps syntax (b, b') (c, c')

(&&&) :: MigrationSteps syntax b c -> MigrationSteps syntax b c' -> MigrationSteps syntax b (c, c')

Category (MigrationSteps syntax :: * -> * -> *)

Defined in Database.Beam.Migrate.Types

Methods

id :: MigrationSteps syntax a a

(.) :: MigrationSteps syntax b c -> MigrationSteps syntax a b -> MigrationSteps syntax a c

type Migration syntax = F (MigrationF syntax)

A sequence of potentially reversible schema update commands

data MigrationF syntax next where

Free monadic function for Migrations

Constructors

MigrationRunCommand :: {..} -> MigrationF syntax next

Fields

• _migrationUpCommand :: syntax

  What to execute when applying the migration

• _migrationDownCommand :: Maybe syntax

  What to execute when unapplying the migration

• _migrationNext :: next

Instances

Functor (MigrationF syntax)

Defined in Database.Beam.Migrate.Types

Methods

fmap :: (a -> b) -> MigrationF syntax a -> MigrationF syntax b

(<$) :: a -> MigrationF syntax b -> MigrationF syntax a

data MigrationCommand cmd

A migration command along with metadata on wheth

Constructors

MigrationCommand

Fields

• migrationCommand :: cmd

  The command to run

• migrationCommandDataLossPossible :: MigrationDataLoss

  Information on whether the migration loses data

Instances

Show cmd => Show (MigrationCommand cmd)

Defined in Database.Beam.Migrate.Types

Methods

showsPrec :: Int -> MigrationCommand cmd -> ShowS

show :: MigrationCommand cmd -> String

showList :: [MigrationCommand cmd] -> ShowS

data MigrationDataLoss

Information on whether a MigrationCommand loses data. You can monoidally combine these to get the potential data loss for a sequence of commands.

Constructors

MigrationLosesData

The command loses data

MigrationKeepsData

The command keeps all data

Instances

Show MigrationDataLoss

Defined in Database.Beam.Migrate.Types

Methods

showsPrec :: Int -> MigrationDataLoss -> ShowS

show :: MigrationDataLoss -> String

showList :: [MigrationDataLoss] -> ShowS

Semigroup MigrationDataLoss

Defined in Database.Beam.Migrate.Types

Methods

(<>) :: MigrationDataLoss -> MigrationDataLoss -> MigrationDataLoss

sconcat :: NonEmpty MigrationDataLoss -> MigrationDataLoss

stimes :: Integral b => b -> MigrationDataLoss -> MigrationDataLoss

Monoid MigrationDataLoss

Defined in Database.Beam.Migrate.Types

Methods

mempty :: MigrationDataLoss

mappend :: MigrationDataLoss -> MigrationDataLoss -> MigrationDataLoss

mconcat :: [MigrationDataLoss] -> MigrationDataLoss

runMigrationSteps

Arguments

:: Monad m

=> Int

Zero-based index of the first step to run

-> Maybe Int

Index of the last step to run, or Nothing to run every step

-> MigrationSteps syntax () a

The set of steps to run

-> (forall a'. Int -> Text -> Migration syntax a' -> m a')

Callback for each step. Called with the step index, the step description and the migration.

-> m a

Run the migration steps between the given indices, using a custom execution function.

runMigrationSilenced :: Migration syntax a -> a

Get the result of a migration, without running any steps

executeMigration :: Applicative m => (syntax -> m ()) -> Migration syntax a -> m a

Execute a given migration, provided a command to execute arbitrary syntax. You usually use this with runNoReturn.

eraseMigrationType :: a -> MigrationSteps syntax a a' -> MigrationSteps syntax () ()

Remove the explicit source and destination schemas from a MigrationSteps object

migrationStep :: Text -> (a -> Migration syntax a') -> MigrationSteps syntax a a'

Create a MigrationSteps from the given description and migration function.

upDown :: syntax -> Maybe syntax -> Migration syntax ()

Given a command in the forward direction, and an optional one in the reverse direction, construct a Migration that performs the given command. Multiple commands can be sequenced monadically.

migrationDataLoss :: Migration syntax a -> MigrationDataLoss

Given a migration, get the potential data loss, if it's run top-down

migrateScript

Arguments

:: (Monoid m, Semigroup m)

=> (Text -> m)

Called at the beginning of each MigrationStep with the step description

-> (syntax -> m)

Called for each command in the migration step

-> MigrationSteps syntax () a

The set of steps to run

-> m

Given functions to render a migration step description and the underlying syntax, create a script for the given MigrationSteps.

evaluateDatabase :: forall syntax a. MigrationSteps syntax () a -> a

Run a MigrationSteps without executing any of the commands against a database.

stepNames :: forall syntax a. MigrationSteps syntax () a -> [Text]

Collect the names of all steps in hte given MigrationSteps