Copyright	(c) digitally induced GmbH 2025
Safe Haskell	None
Language	GHC2021

IHP.Hasql.FromRow

Contents

Orphan instances

Description

This module provides FromRowHasql, a typeclass parallel to postgresql-simple's FromRow, for decoding database rows using hasql's more efficient prepared statement approach.

Instances are generated by the SchemaCompiler with explicit inline decoders in idiomatic hasql applicative style.

Also provides parser functions used by the generated decoders for custom PostgreSQL types.

Synopsis

class FromRowHasql a where
- hasqlRowDecoder :: Row a
class HasqlDecodeColumn a where
- hasqlColumnDecoder :: Row a

Documentation

class FromRowHasql a where Source #

Typeclass for types that can be decoded from a hasql result row

This is the hasql equivalent of postgresql-simple's FromRow class. The SchemaCompiler generates instances for all model types using idiomatic hasql applicative style with explicit inline decoders.

Methods

hasqlRowDecoder :: Row a Source #

Decoder for a single row

Instances

Instances details

HasqlDecodeColumn a => FromRowHasql (Only a) Source #
Instance details Defined in IHP.Hasql.FromRow Methods hasqlRowDecoder :: Row (Only a) Source #
(HasqlDecodeColumn a, HasqlDecodeColumn b) => FromRowHasql (a, b) Source #
Instance details Defined in IHP.Hasql.FromRow Methods hasqlRowDecoder :: Row (a, b) Source #
(HasqlDecodeColumn a, HasqlDecodeColumn b, HasqlDecodeColumn c) => FromRowHasql (a, b, c) Source #
Instance details Defined in IHP.Hasql.FromRow Methods hasqlRowDecoder :: Row (a, b, c) Source #
(HasqlDecodeColumn a, HasqlDecodeColumn b, HasqlDecodeColumn c, HasqlDecodeColumn d) => FromRowHasql (a, b, c, d) Source #
Instance details Defined in IHP.Hasql.FromRow Methods hasqlRowDecoder :: Row (a, b, c, d) Source #
(HasqlDecodeColumn a, HasqlDecodeColumn b, HasqlDecodeColumn c, HasqlDecodeColumn d, HasqlDecodeColumn e) => FromRowHasql (a, b, c, d, e) Source #
Instance details Defined in IHP.Hasql.FromRow Methods hasqlRowDecoder :: Row (a, b, c, d, e) Source #

class HasqlDecodeColumn a where Source #

Typeclass for building column-level row decoders, handling nullable/non-nullable. Uses IsScalar from hasql-mapping for value-level decoding.

Methods

hasqlColumnDecoder :: Row a Source #

Instances

Instances details

HasqlDecodeColumn Int Source #	IHP's schema maps SQL `INT` (int4) to Haskell `Int`, but hasql-mapping's `IsScalar Int` instance uses `int8` (bigint). Override to match IHP conventions.
Instance details Defined in IHP.Hasql.FromRow Methods hasqlColumnDecoder :: Row Int Source #
IsScalar a => HasqlDecodeColumn a Source #
Instance details Defined in IHP.Hasql.FromRow Methods hasqlColumnDecoder :: Row a Source #
IsScalar (PrimaryKey table) => HasqlDecodeColumn (Id' table) Source #	Decode `Id` table' by decoding the primary key type and wrapping with `Id`
Instance details Defined in IHP.Hasql.FromRow Methods hasqlColumnDecoder :: Row (Id' table) Source #
IsScalar (PrimaryKey table) => HasqlDecodeColumn (Maybe (Id' table)) Source #	Decode 'Maybe (Id' table)' for nullable foreign keys
Instance details Defined in IHP.Hasql.FromRow Methods hasqlColumnDecoder :: Row (Maybe (Id' table)) Source #
HasqlDecodeColumn (Maybe Int) Source #
Instance details Defined in IHP.Hasql.FromRow Methods hasqlColumnDecoder :: Row (Maybe Int) Source #
IsScalar a => HasqlDecodeColumn (Maybe a) Source #
Instance details Defined in IHP.Hasql.FromRow Methods hasqlColumnDecoder :: Row (Maybe a) Source #

Orphan instances

IsScalar Integer Source #	IHP's schema maps SQL `BIGINT`/`BIGSERIAL` to Haskell `Integer` (see `atomicType` in `SchemaCompiler`). `hasql-mapping` ships no 'IsScalar Integer' instance, so `BIGSERIAL` primary keys (and foreign keys referencing them) fail to typecheck in generated `RowDecoder` modules with `No instance for Mapping.IsScalar Integer`. Provide one backed by the `int8` codec, mirroring the 'DefaultParamEncoder Integer' instance in IHP.Hasql.Encoders.
Instance details Methods encoder :: Value Integer Source # decoder :: Value Integer Source #
IsScalar (PrimaryKey table) => IsScalar (Id' table) Source #	`IsScalar` instance for `Id'` so that Id columns can use `encoder` and `decoder` directly in generated code, without manual wrapping/unwrapping.
Instance details Methods encoder :: Value (Id' table) Source # decoder :: Value (Id' table) Source #