Database.Selda.Backend · selda-0.5.2.1

classclass MonadIO m => MonadSelda (m :: Type -> Type) where

#

Some monad with Selda SQL capabilitites.

Associated types

type family Backend (m :: Type -> Type)
Type of database backend used by m.

Methods

withConnection :: (SeldaConnection (Backend m) -> m a) -> m a
Pass a Selda connection to the given computation and execute it. After the computation finishes, withConnection is free to do anything it likes to the connection, including closing it or giving it to another Selda computation. Thus, the computation must take care never to return or otherwise access the connection after returning.
transact :: m a -> m a
Perform the given computation as a transaction. Implementations must ensure that subsequent calls to withConnection within the same transaction always passes the same connection to its argument.

Instances1MonadSelda

(MonadIO m, MonadMask m) => MonadSelda (SeldaT b m)Defined in selda-0.5.2.1 · Database.Selda.Backend.Internal

newtypenewtype SeldaT b (m :: Type -> Type) a

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Monad transformer adding Selda SQL capabilities.

Instances11MonadTrans, Monad, Functor, MonadFail, Applicative, MonadIO, …

MonadTrans (SeldaT b)Defined in selda-0.5.2.1 · Database.Selda.Backend.Internal
Monad m => Monad (SeldaT b m)Defined in selda-0.5.2.1 · Database.Selda.Backend.Internal
Functor m => Functor (SeldaT b m)Defined in selda-0.5.2.1 · Database.Selda.Backend.Internal
MonadFail m => MonadFail (SeldaT b m)Defined in selda-0.5.2.1 · Database.Selda.Backend.Internal
Applicative m => Applicative (SeldaT b m)Defined in selda-0.5.2.1 · Database.Selda.Backend.Internal
MonadIO m => MonadIO (SeldaT b m)Defined in selda-0.5.2.1 · Database.Selda.Backend.Internal
MonadCatch m => MonadCatch (SeldaT b m)Defined in selda-0.5.2.1 · Database.Selda.Backend.Internal
MonadMask m => MonadMask (SeldaT b m)Defined in selda-0.5.2.1 · Database.Selda.Backend.Internal
MonadThrow m => MonadThrow (SeldaT b m)Defined in selda-0.5.2.1 · Database.Selda.Backend.Internal
(MonadIO m, MonadMask m) => MonadSelda (SeldaT b m)Defined in selda-0.5.2.1 · Database.Selda.Backend.Internal
type Backend (SeldaT b m) = bDefined in selda-0.5.2.1 · Database.Selda.Backend.Internal

typetype SeldaM b = SeldaT b IO

#

The simplest form of Selda computation; SeldaT specialized to IO.

datadata SeldaError

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Thrown by any function in SeldaT if an error occurs.

Constructors

DbError String
Unable to open or connect to database.
SqlError String
An error occurred while executing query.
UnsafeError String
An error occurred due to improper use of an unsafe function.

Instances3Eq, Show, Exception

Eq SeldaErrorDefined in selda-0.5.2.1 · Database.Selda.Backend.Internal
Show SeldaErrorDefined in selda-0.5.2.1 · Database.Selda.Backend.Internal
Exception SeldaErrorDefined in selda-0.5.2.1 · Database.Selda.Backend.Internal

newtypenewtype StmtID

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A prepared statement identifier. Guaranteed to be unique per application.

Instances3Eq, Ord, Show

Eq StmtIDDefined in selda-0.5.2.1 · Database.Selda.Backend.Internal
Ord StmtIDDefined in selda-0.5.2.1 · Database.Selda.Backend.Internal
Show StmtIDDefined in selda-0.5.2.1 · Database.Selda.Backend.Internal

datadata BackendID

#

Uniquely identifies some particular backend.

When publishing a new backend, consider submitting a pull request with a constructor for your backend instead of using the Other constructor.

Constructors

Instances3Eq, Ord, Show

Eq BackendIDDefined in selda-0.5.2.1 · Database.Selda.Backend.Internal
Ord BackendIDDefined in selda-0.5.2.1 · Database.Selda.Backend.Internal
Show BackendIDDefined in selda-0.5.2.1 · Database.Selda.Backend.Internal

typetype QueryRunner a = Text -> [Param] -> IO a

#

A function which executes a query and gives back a list of extensible tuples; one tuple per result row, and one tuple element per column.

datadata SeldaBackend b

#

A collection of functions making up a Selda backend.

Constructors

SeldaBackend
- runStmt :: Text -> [Param] -> IO (Int, [[SqlValue]])
  Execute an SQL statement.
- runStmtWithPK :: Text -> [Param] -> IO Int64
  Execute an SQL statement and return the last inserted primary key, where the primary key is auto-incrementing. Backends must take special care to make this thread-safe.
- prepareStmt :: StmtID -> [SqlTypeRep] -> Text -> IO Dynamic
  Prepare a statement using the given statement identifier.
- runPrepared :: Dynamic -> [Param] -> IO (Int, [[SqlValue]])
  Execute a prepared statement.
- getTableInfo :: TableName -> IO TableInfo
  Get a list of all columns in the given table, with the type and any modifiers for each column. Return an empty list if the given table does not exist.
- ppConfig :: PPConfig
  SQL pretty-printer configuration.
- closeConnection :: SeldaConnection b -> IO ()
  Close the currently open connection.
- backendId :: BackendID
  Unique identifier for this backend.
- disableForeignKeys :: Bool -> IO ()
  Turn on or off foreign key checking, and initiate/commit a transaction.
  When implementing this function, it is safe to assume that disableForeignKeys True will always be called exactly once before each disableForeignKeys False.

datadata SeldaConnection b

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datadata SqlValue where

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Some value that is representable in SQL.

Constructors

Instances1Show

Show SqlValueDefined in selda-0.5.2.1 · Database.Selda.SqlType

datadata IndexMethod

#

Method to use for indexing with indexedUsing. Index methods are ignored by the SQLite backend, as SQLite doesn't support different index methods.

BTreeIndex HashIndex

Instances3Eq, Ord, Show

Eq IndexMethodDefined in selda-0.5.2.1 · Database.Selda.Table.Type
Ord IndexMethodDefined in selda-0.5.2.1 · Database.Selda.Table.Type
Show IndexMethodDefined in selda-0.5.2.1 · Database.Selda.Table.Type

datadata Param where

#

A parameter to a prepared SQL statement.

Constructors

Param :: !Lit a -> Param

Instances3Eq, Ord, Show

Eq ParamDefined in selda-0.5.2.1 · Database.Selda.SQL
Ord ParamDefined in selda-0.5.2.1 · Database.Selda.SQL
Show ParamDefined in selda-0.5.2.1 · Database.Selda.SQL

datadata ColAttr

#

Column attributes such as nullability, auto increment, etc. When adding elements, make sure that they are added in the order required by SQL syntax, as this list is only sorted before being pretty-printed.

Constructors

Instances3Eq, Ord, Show

Eq ColAttrDefined in selda-0.5.2.1 · Database.Selda.Table.Type
Ord ColAttrDefined in selda-0.5.2.1 · Database.Selda.Table.Type
Show ColAttrDefined in selda-0.5.2.1 · Database.Selda.Table.Type

datadata AutoIncType

#

Strongly or weakly auto-incrementing primary key?

Weak Strong

Instances3Eq, Ord, Show

Eq AutoIncTypeDefined in selda-0.5.2.1 · Database.Selda.Table.Type
Ord AutoIncTypeDefined in selda-0.5.2.1 · Database.Selda.Table.Type
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datadata PPConfig

#

Backend-specific configuration for the SQL pretty-printer.

Constructors

PPConfig
- ppType :: SqlTypeRep -> Text
  The SQL type name of the given type.
  This function should be used everywhere a type is needed to be printed but in primary keys position. This is due to the fact that some backends might have a special representation of primary keys (using sequences are such). If you have such a need, please use the ppTypePK record instead.
- ppTypeHook :: SqlTypeRep -> [ColAttr] -> (SqlTypeRep -> Text) -> Text
  Hook that allows you to modify ppType output.
- ppTypePK :: SqlTypeRep -> Text
  The SQL type name of the given type for primary keys uses.
- ppPlaceholder :: Int -> Text
  Parameter placeholder for the nth parameter.
- ppColAttrs :: [ColAttr] -> Text
  List of column attributes.
- ppColAttrsHook :: SqlTypeRep -> [ColAttr] -> ([ColAttr] -> Text) -> Text
  Hook that allows you to modify ppColAttrs output.
- ppAutoIncInsert :: Text
  The value used for the next value for an auto-incrementing column. For instance, DEFAULT for PostgreSQL, and NULL for SQLite.
- ppMaxInsertParams :: Maybe Int
  Insert queries may have at most this many parameters; if an insertion has more parameters than this, it will be chunked.
  Note that only insertions of multiple rows are chunked. If your table has more than this many columns, you should really rethink your database design.
- ppIndexMethodHook :: IndexMethod -> Text
  CREATE INDEX suffix to indicate that the index should use the given index method.

valuedefPPConfig :: PPConfig

#

Default settings for pretty-printing. Geared towards SQLite.

The default definition of ppTypePK is 'defType, so that you don’t have to do anything special if you don’t use special types for primary keys.

newtypenewtype TableName

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Name of a database table.

Instances4Eq, Ord, Show, IsString

Eq TableNameDefined in selda-0.5.2.1 · Database.Selda.Types
Ord TableNameDefined in selda-0.5.2.1 · Database.Selda.Types
Show TableNameDefined in selda-0.5.2.1 · Database.Selda.Types
IsString TableNameDefined in selda-0.5.2.1 · Database.Selda.Types

newtypenewtype ColName

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Name of a database column.

Instances4Eq, Ord, Show, IsString

Eq ColNameDefined in selda-0.5.2.1 · Database.Selda.Types
Ord ColNameDefined in selda-0.5.2.1 · Database.Selda.Types
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IsString ColNameDefined in selda-0.5.2.1 · Database.Selda.Types

datadata TableInfo

#

Comprehensive information about a table.

Constructors

TableInfo
- tableInfoName :: TableName
  Name of the table.
- tableColumnInfos :: [ColumnInfo]
  Ordered information about each table column.
- tableUniqueGroups :: [[ColName]]
  Unordered list of all (non-PK) uniqueness constraints on this table.
- tablePrimaryKey :: [ColName]
  Unordered list of all primary key constraints on this table.

Instances2Eq, Show

Eq TableInfoDefined in selda-0.5.2.1 · Database.Selda.Backend.Internal
Show TableInfoDefined in selda-0.5.2.1 · Database.Selda.Backend.Internal

datadata ColumnInfo

#

Comprehensive information about a column.

Constructors

ColumnInfo
- colName :: ColName
  Name of the column.
- colType :: Either Text SqlTypeRep
  Selda type of the column, or the type name given by the database if Selda couldn't make sense of the type.
- colIsAutoPrimary :: Bool
  Is the given column auto-incrementing?
- colIsNullable :: Bool
  Can the column be NULL?
- colHasIndex :: Bool
  Is the column explicitly indexed (i.e. using indexed)?
- colFKs :: [(TableName, ColName)]
  Any foreign key (table, column) pairs referenced by this column.

Instances2Eq, Show

Eq ColumnInfoDefined in selda-0.5.2.1 · Database.Selda.Backend.Internal
Show ColumnInfoDefined in selda-0.5.2.1 · Database.Selda.Backend.Internal

valueisAutoPrimary :: ColAttr -> Bool

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valueisPrimary :: ColAttr -> Bool

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valueisUnique :: ColAttr -> Bool

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valuetableInfo :: Table a -> TableInfo

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Get the column information for each column in the given table.

valuefromColInfo :: ColInfo -> ColumnInfo

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Convert a ColInfo into a ColumnInfo.

valuemkTableName :: Text -> TableName

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Create a column name.

valuemkColName :: Text -> ColName

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Create a column name.

valuefromTableName :: TableName -> Text

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Convert a table name into a string, with quotes.

valuefromColName :: ColName -> Text

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Convert a column name into a string, with quotes.

valuerawTableName :: TableName -> Text

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Convert a table name into a string, without quotes.

valuenewConnection

:: MonadIO m
=> SeldaBackend b
-> Text
-> m (SeldaConnection b)

#

Create a new Selda connection for the given backend and database identifier string.

valueallStmts :: SeldaConnection b -> IO [(StmtID, Dynamic)]

#

Get all statements and their corresponding identifiers for the current connection.

valuewithBackend :: MonadSelda m => (SeldaBackend (Backend m) -> m a) -> m a

#

Get the backend in use by the computation.

valuerunSeldaT

:: (MonadIO m, MonadMask m)
=> SeldaT b m a
-> SeldaConnection b
-> m a

#

Run a Selda transformer. Backends should use this to implement their withX functions.

valueseldaClose :: MonadIO m => SeldaConnection b -> m ()

#

Close a reusable Selda connection. Closing a connection while in use is undefined. Passing a closed connection to runSeldaT results in a SeldaError being thrown. Closing a connection more than once is a no-op.