Database.PostgreSQL.LTree

This module provides types and functions for PostgreSQL's ltree https://www.postgresql.org/docs/current/ltree.html

You will want to use a specific implementation, e.g. postgresql-simple-ltree.

Documentation

newtype LTree

Wrapper for Postgres' ltree (label tree) type.

Constructors

LTree

Fields

• unLTree :: Seq Label

Instances

Eq LTree

Defined in Database.PostgreSQL.LTree

Methods

(==) :: LTree -> LTree -> Bool

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

Ord LTree

Defined in Database.PostgreSQL.LTree

Methods

compare :: LTree -> LTree -> Ordering

(<) :: LTree -> LTree -> Bool

(<=) :: LTree -> LTree -> Bool

(>) :: LTree -> LTree -> Bool

(>=) :: LTree -> LTree -> Bool

max :: LTree -> LTree -> LTree

min :: LTree -> LTree -> LTree

Show LTree

Defined in Database.PostgreSQL.LTree

Methods

showsPrec :: Int -> LTree -> ShowS

show :: LTree -> String

showList :: [LTree] -> ShowS

ToJSON LTree

Defined in Database.PostgreSQL.LTree

Methods

toJSON :: LTree -> Value

toEncoding :: LTree -> Encoding

toJSONList :: [LTree] -> Value

toEncodingList :: [LTree] -> Encoding

FromJSON LTree

Defined in Database.PostgreSQL.LTree

Methods

parseJSON :: Value -> Parser LTree

parseJSONList :: Value -> Parser [LTree]

data Label

Wrapper for a single label in an ltree. The constructor IS NOT exported to ensure we only construct valid labels. See mkLabel for constructing a Label.

Instances

Eq Label

Defined in Database.PostgreSQL.LTree

Methods

(==) :: Label -> Label -> Bool

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

Ord Label

Defined in Database.PostgreSQL.LTree

Methods

compare :: Label -> Label -> Ordering

(<) :: Label -> Label -> Bool

(<=) :: Label -> Label -> Bool

(>) :: Label -> Label -> Bool

(>=) :: Label -> Label -> Bool

max :: Label -> Label -> Label

min :: Label -> Label -> Label

Show Label

Defined in Database.PostgreSQL.LTree

Methods

showsPrec :: Int -> Label -> ShowS

show :: Label -> String

showList :: [Label] -> ShowS

ToJSON Label

Defined in Database.PostgreSQL.LTree

Methods

toJSON :: Label -> Value

toEncoding :: Label -> Encoding

toJSONList :: [Label] -> Value

toEncodingList :: [Label] -> Encoding

FromJSON Label

Defined in Database.PostgreSQL.LTree

Methods

parseJSON :: Value -> Parser Label

parseJSONList :: Value -> Parser [Label]

map :: (Label -> Label) -> LTree -> LTree

Produce a new LTree by applying the supplied function to each Label.

fromList :: [Label] -> LTree

Convert a list to an LTree.

toList :: LTree -> [Label]

Convert an LTree to a list.

rootLabel :: LTree -> Maybe Label

Get the first Label from an LTree if one exists.

parentLabel :: LTree -> Maybe Label

Get the second-to-last Label in an LTree.

parent :: LTree -> Maybe LTree

Get the parent path of an LTree.

numLabels :: LTree -> Int

Get the length of an LTree.

mkLabel :: Text -> Either String Label

Safely construct a Label from Text. If the supplied Text contains characters unsupported by ltree. On failure, returns Left with an error message.

unsafeMkLabel :: Text -> Label

Same as mkLabel except throws an error for an invalid Text input.

uuidToLabel :: UUID -> Label

A UUID can always be converted into a Label without error by dropping the hyphens. The resulting Label will only contain numbers and lower-case alpha characters.

empty :: LTree

An empty LTree.

null :: LTree -> Bool

Test whether an LTree is empty.

singleton :: Label -> LTree

Construct an LTree from a single Label.

snoc :: LTree -> Label -> LTree

Append a single Label to the end of an LTree; should be O(1) since it's delegating to |>

render :: LTree -> Text

Render an ltree as it would appear in the database.

unsafeUncheckedParse :: Text -> LTree

Unsafely parse an LTree from Text assuming each Label is valid. Use this only if you sure the input is a valid LTree; e.g. it was fetched from a field the database of type ltree.

parse :: Text -> Either String LTree

Parse an LTree from Text. If any Label present is invalid, returns Left.

isImmediateParentOf :: LTree -> LTree -> Bool

Test whether the first LTree is an immediate parent of the second; e.g. a.b is an immediate parent of a.b.c

isImmediateChildOf :: LTree -> LTree -> Bool

Test whether the first LTree is an immediate child of the second; e.g. a.b.c is an immediate child of a.b

parseUUIDFromLabel :: Label -> Either String UUID

Attempt to parse a UUID from a Label.

allLabelsUnique :: LTree -> Bool

Test whether all labels in the LTree are unique.