Database.PostgreSQL.Models

Type classes for PostgreSQL-backed data models.

Documentation

class FromParams p where

Methods

fromParams :: [Param] -> Maybe p

Converts an HTML form into a type

Instances

(FromParams a, FromParams b) => FromParams (a, b)

type Param = (ByteString, ByteString)

Post parameter name and value.

class (FromRow p, ToRow p, ToField (PrimaryKey p), FromField (PrimaryKey p)) => PostgreSQLModel p where

Basis type for PostgreSQL-backed data-models. Instances must, at minimum, implement primaryKey, tableName and columns. /Note: the column ordering must match that used in the type's implementation of FromRow and ToRow/

Associated Types

type PrimaryKey p :: *

Methods

primaryKey :: p -> Maybe (PrimaryKey p)

Given a model, returns the value of it's primary key. In many cases, this will simply be an alias to a record accessor.

tableName :: p -> TableName p

Returns the TableName of the model. Instances should have a top-level value for the TableName that is always returned. For example:

 employees :: TableName Employee
 employees = TableName "employees"

 instance PostgreSQLModel Employee where
   ...
   tableName _ = employess

columns :: TableName p -> [String]

Column names excluding primary key. Column order must match the ordering used in ToRow and FromRow.

primaryKeyName :: TableName p -> String

Name of primary key column (default: "id").

columns_ :: TableName p -> [String]

Column names with primary-key name prepended.

orderBy :: TableName p -> Maybe String

insert :: p -> Connection -> IO (PrimaryKey p)

Inserts the model into the database. It relies on the primary key being autogenerated by the database.

upsert :: p -> Connection -> IO (PrimaryKey p)

Create or update the model (uses the primary key to determine if the model already exists in the database)

find :: TableName p -> PrimaryKey p -> Connection -> IO (Maybe p)

Retrieves the single model corresponding to the given primary key

findFirst

Arguments

:: ToField f

=> TableName p

-> String

Search column name

-> f

Search value

-> Connection

-> IO (Maybe p)

Finds the first model in the database based on the column-value contstraint.

findAll :: TableName p -> Connection -> IO [p]

Retrieves all models in the table

findAllBy

Arguments

:: ToField f

=> TableName p

-> String

Search column name

-> f

Search value

-> Connection

-> IO [p]

Retrieves all models in the table subject to the column-value constraint.

class (PostgreSQLModel parent, PostgreSQLModel child) => HasMany parent child where

Defines a "has-many" relationship between two models, where the parent model may be associated with zero or more of the child model. Specifically, the child table has a foreign key column pointing to the parent model.

Methods

foreignKey :: TableName parent -> TableName child -> String

childrenOf :: parent -> TableName child -> Connection -> IO [child]

childOf :: parent -> TableName child -> PrimaryKey child -> Connection -> IO (Maybe child)

childOfBy :: ToField v => parent -> TableName child -> String -> v -> Connection -> IO (Maybe child)

childrenOfBy :: ToField f => parent -> TableName child -> String -> f -> Connection -> IO [child]

insertFor :: parent -> child -> Connection -> IO (PrimaryKey child)

newtype TableName p

Wrapper type representing PostgreSQL table names

Constructors

TableName String

Instances

Eq (TableName p)

Show (TableName p)

fromTableName :: TableName p -> String

Unwraps a TableName

fromString :: IsString a => String -> a

class IsString a where

Class for string-like datastructures; used by the overloaded string extension (-foverloaded-strings in GHC).

Methods

fromString :: String -> a

Instances

IsString ByteString

IsString ByteString

IsString Text

IsString Text

IsString Query

IsString [Char]

~ * a ByteString => IsString (Parser a)

(IsString s, FoldCase s) => IsString (CI s)