mirror of
https://github.com/simonmichael/hledger.git
synced 2024-11-09 00:15:48 +03:00
254 lines
9.6 KiB
Haskell
254 lines
9.6 KiB
Haskell
{-
|
||
JSON instances. Should they be in Types.hs ?
|
||
-}
|
||
|
||
{-# OPTIONS_GHC -fno-warn-orphans #-}
|
||
|
||
{-# LANGUAGE CPP #-}
|
||
--{-# LANGUAGE DataKinds #-}
|
||
--{-# LANGUAGE DeriveAnyClass #-}
|
||
{-# LANGUAGE DeriveGeneric #-}
|
||
--{-# LANGUAGE FlexibleContexts #-}
|
||
{-# LANGUAGE FlexibleInstances #-}
|
||
--{-# LANGUAGE NamedFieldPuns #-}
|
||
--{-# LANGUAGE OverloadedStrings #-}
|
||
{-# LANGUAGE OverloadedStrings #-}
|
||
--{-# LANGUAGE PolyKinds #-}
|
||
--{-# LANGUAGE QuasiQuotes #-}
|
||
--{-# LANGUAGE QuasiQuotes #-}
|
||
--{-# LANGUAGE Rank2Types #-}
|
||
--{-# LANGUAGE RankNTypes #-}
|
||
{-# LANGUAGE RecordWildCards #-}
|
||
--{-# LANGUAGE ScopedTypeVariables #-}
|
||
{-# LANGUAGE StandaloneDeriving #-}
|
||
--{-# LANGUAGE TemplateHaskell #-}
|
||
--{-# LANGUAGE TypeFamilies #-}
|
||
--{-# LANGUAGE TypeOperators #-}
|
||
|
||
module Hledger.Data.Json (
|
||
-- * Instances
|
||
-- * Utilities
|
||
toJsonText
|
||
,writeJsonFile
|
||
,readJsonFile
|
||
) where
|
||
|
||
#if !(MIN_VERSION_base(4,13,0))
|
||
import Data.Semigroup ((<>))
|
||
#endif
|
||
import Data.Aeson
|
||
import Data.Aeson.Encode.Pretty (encodePrettyToTextBuilder)
|
||
--import Data.Aeson.TH
|
||
import qualified Data.ByteString.Lazy as BL
|
||
import Data.Decimal
|
||
import Data.Maybe
|
||
import qualified Data.Text.Lazy as TL
|
||
import qualified Data.Text.Lazy.IO as TL
|
||
import Data.Text.Lazy.Builder (toLazyText)
|
||
import GHC.Generics (Generic)
|
||
import System.Time (ClockTime)
|
||
|
||
import Hledger.Data.Types
|
||
|
||
-- To JSON
|
||
|
||
instance ToJSON Status
|
||
instance ToJSON GenericSourcePos
|
||
|
||
-- https://github.com/simonmichael/hledger/issues/1195
|
||
|
||
-- The default JSON output for Decimal can contain 255-digit integers
|
||
-- (for repeating decimals caused by implicit transaction prices).
|
||
-- JSON output is intended to be consumed by diverse apps and
|
||
-- programming languages, which can't handle numbers like that.
|
||
-- From #1195:
|
||
--
|
||
-- > - JavaScript uses 64-bit IEEE754 numbers which can only accurately
|
||
-- > represent integers up to 9007199254740991 (i.e. a maximum of 15 digits).
|
||
-- > - Java’s largest integers are limited to 18 digits.
|
||
-- > - Python 3 integers are unbounded.
|
||
-- > - Python 2 integers are limited to 18 digits like Java.
|
||
-- > - C and C++ number limits depend on platform — most platforms should
|
||
-- > be able to represent unsigned integers up to 64 bits, i.e. 19 digits.
|
||
--
|
||
-- What is the best compromise for both accuracy and practicality ?
|
||
-- For now, we provide both the maximum precision representation
|
||
-- (decimalPlaces & decimalMantissa), and a floating point representation
|
||
-- with up to 10 decimal places (and an unbounded number of integer digits).
|
||
-- We hope the mere presence of the large number in JSON won't break things,
|
||
-- and that the overall number of significant digits in the floating point
|
||
-- remains manageable in practice. (I'm not sure how to limit the number
|
||
-- of significant digits in a Decimal right now.)
|
||
instance ToJSON Decimal where
|
||
toJSON d = object
|
||
["decimalPlaces" .= toJSON decimalPlaces
|
||
,"decimalMantissa" .= toJSON decimalMantissa
|
||
,"floatingPoint" .= toJSON (fromRational $ toRational d' :: Double)
|
||
]
|
||
where d'@Decimal{..} = roundTo 10 d
|
||
|
||
instance ToJSON Amount
|
||
instance ToJSON AmountStyle
|
||
instance ToJSON AmountPrecision
|
||
instance ToJSON Side
|
||
instance ToJSON DigitGroupStyle
|
||
instance ToJSON MixedAmount
|
||
instance ToJSON BalanceAssertion
|
||
instance ToJSON AmountPrice
|
||
instance ToJSON MarketPrice
|
||
instance ToJSON PostingType
|
||
|
||
instance ToJSON Posting where
|
||
toJSON Posting{..} = object
|
||
["pdate" .= pdate
|
||
,"pdate2" .= pdate2
|
||
,"pstatus" .= pstatus
|
||
,"paccount" .= paccount
|
||
,"pamount" .= pamount
|
||
,"pcomment" .= pcomment
|
||
,"ptype" .= ptype
|
||
,"ptags" .= ptags
|
||
,"pbalanceassertion" .= pbalanceassertion
|
||
-- To avoid a cycle, show just the parent transaction's index number
|
||
-- in a dummy field. When re-parsed, there will be no parent.
|
||
,"ptransaction_" .= maybe "" (show.tindex) ptransaction
|
||
-- This is probably not wanted in json, we discard it.
|
||
,"poriginal" .= (Nothing :: Maybe Posting)
|
||
]
|
||
|
||
instance ToJSON Transaction
|
||
instance ToJSON TransactionModifier
|
||
instance ToJSON PeriodicTransaction
|
||
instance ToJSON PriceDirective
|
||
instance ToJSON DateSpan
|
||
instance ToJSON Interval
|
||
instance ToJSON AccountAlias
|
||
instance ToJSON AccountType
|
||
instance ToJSONKey AccountType
|
||
instance ToJSON AccountDeclarationInfo
|
||
instance ToJSON Commodity
|
||
instance ToJSON TimeclockCode
|
||
instance ToJSON TimeclockEntry
|
||
instance ToJSON ClockTime
|
||
instance ToJSON Journal
|
||
|
||
instance ToJSON Account where
|
||
toJSON a = object
|
||
["aname" .= aname a
|
||
,"aebalance" .= aebalance a
|
||
,"aibalance" .= aibalance a
|
||
,"anumpostings" .= anumpostings a
|
||
,"aboring" .= aboring a
|
||
-- To avoid a cycle, show just the parent account's name
|
||
-- in a dummy field. When re-parsed, there will be no parent.
|
||
,"aparent_" .= maybe "" aname (aparent a)
|
||
-- Just the names of subaccounts, as a dummy field, ignored when parsed.
|
||
,"asubs_" .= map aname (asubs a)
|
||
-- The actual subaccounts (and their subs..), making a (probably highly redundant) tree
|
||
-- ,"asubs" .= asubs a
|
||
-- Omit the actual subaccounts
|
||
,"asubs" .= ([]::[Account])
|
||
]
|
||
|
||
deriving instance Generic (Ledger)
|
||
instance ToJSON Ledger
|
||
|
||
-- From JSON
|
||
|
||
instance FromJSON Status
|
||
instance FromJSON GenericSourcePos
|
||
instance FromJSON Amount
|
||
instance FromJSON AmountStyle
|
||
instance FromJSON AmountPrecision
|
||
instance FromJSON Side
|
||
instance FromJSON DigitGroupStyle
|
||
instance FromJSON MixedAmount
|
||
instance FromJSON BalanceAssertion
|
||
instance FromJSON AmountPrice
|
||
instance FromJSON MarketPrice
|
||
instance FromJSON PostingType
|
||
instance FromJSON Posting
|
||
instance FromJSON Transaction
|
||
instance FromJSON AccountDeclarationInfo
|
||
-- XXX The ToJSON instance replaces subaccounts with just names.
|
||
-- Here we should try to make use of those to reconstruct the
|
||
-- parent-child relationships.
|
||
instance FromJSON Account
|
||
|
||
-- Decimal, various attempts
|
||
--
|
||
-- https://stackoverflow.com/questions/40331851/haskell-data-decimal-as-aeson-type
|
||
----instance FromJSON Decimal where parseJSON =
|
||
---- A.withScientific "Decimal" (return . right . eitherFromRational . toRational)
|
||
--
|
||
-- https://github.com/bos/aeson/issues/474
|
||
-- http://hackage.haskell.org/package/aeson-1.4.2.0/docs/Data-Aeson-TH.html
|
||
-- $(deriveFromJSON defaultOptions ''Decimal) -- doesn't work
|
||
-- $(deriveFromJSON defaultOptions ''DecimalRaw) -- works; requires TH, but gives better parse error messages
|
||
--
|
||
-- https://github.com/PaulJohnson/Haskell-Decimal/issues/6
|
||
--deriving instance Generic Decimal
|
||
--instance FromJSON Decimal
|
||
deriving instance Generic (DecimalRaw a)
|
||
instance FromJSON (DecimalRaw Integer)
|
||
--
|
||
-- @simonmichael, I think the code in your first comment should work if it compiles—though “work” doesn’t mean you can parse a JSON number directly into a `Decimal` using the generic instance, as you’ve discovered.
|
||
--
|
||
--Error messages with these extensions are always rather cryptic, but I’d prefer them to Template Haskell. Typically you’ll want to start by getting a generic `ToJSON` instance working, then use that to figure out what the `FromJSON` instance expects to parse: for a correct instance, `encode` and `decode` should give you an isomorphism between your type and a subset of `Bytestring` (up to the `Maybe` wrapper that `decode` returns).
|
||
--
|
||
--I don’t have time to test it right now, but I think it will also work without `DeriveAnyClass`, just using `DeriveGeneric` and `StandAloneDeriving`. It should also work to use the [`genericParseJSON`](http://hackage.haskell.org/package/aeson/docs/Data-Aeson.html#v:genericParseJSON) function to implement the class explicitly, something like this:
|
||
--
|
||
--{-# LANGUAGE DeriveGeneric #-}
|
||
--{-# LANGUAGE StandAloneDeriving #-}
|
||
--import GHC.Generics
|
||
--import Data.Aeson
|
||
--deriving instance Generic Decimal
|
||
--instance FromJSON Decimal where
|
||
-- parseJSON = genericParseJSON defaultOptions
|
||
--
|
||
--And of course you can avoid `StandAloneDeriving` entirely if you’re willing to wrap `Decimal` in your own `newtype`.
|
||
|
||
-- XXX these will allow reading a Journal, but currently the
|
||
-- jdeclaredaccounttypes Map gets serialised as a JSON list, which
|
||
-- can't be read back.
|
||
--
|
||
-- instance FromJSON AccountAlias
|
||
-- instance FromJSONKey AccountType where fromJSONKey = genericFromJSONKey defaultJSONKeyOptions
|
||
-- instance FromJSON AccountType
|
||
-- instance FromJSON ClockTime
|
||
-- instance FromJSON Commodity
|
||
-- instance FromJSON DateSpan
|
||
-- instance FromJSON Interval
|
||
-- instance FromJSON PeriodicTransaction
|
||
-- instance FromJSON PriceDirective
|
||
-- instance FromJSON TimeclockCode
|
||
-- instance FromJSON TimeclockEntry
|
||
-- instance FromJSON TransactionModifier
|
||
-- instance FromJSON Journal
|
||
|
||
|
||
-- Utilities
|
||
|
||
-- | Show a JSON-convertible haskell value as pretty-printed JSON text.
|
||
toJsonText :: ToJSON a => a -> TL.Text
|
||
toJsonText = (<>"\n") . toLazyText . encodePrettyToTextBuilder
|
||
|
||
-- | Write a JSON-convertible haskell value to a pretty-printed JSON file.
|
||
-- Eg: writeJsonFile "a.json" nulltransaction
|
||
writeJsonFile :: ToJSON a => FilePath -> a -> IO ()
|
||
writeJsonFile f = TL.writeFile f . toJsonText
|
||
-- we write with Text and read with ByteString, is that fine ?
|
||
|
||
-- | Read a JSON file and decode it to the target type, or raise an error if we can't.
|
||
-- Eg: readJsonFile "a.json" :: IO Transaction
|
||
readJsonFile :: FromJSON a => FilePath -> IO a
|
||
readJsonFile f = do
|
||
bl <- BL.readFile f
|
||
-- PARTIAL:
|
||
let v = fromMaybe (error $ "could not decode JSON in "++show f++" to target value")
|
||
(decode bl :: Maybe Value)
|
||
case fromJSON v :: FromJSON a => Result a of
|
||
Error e -> error e
|
||
Success t -> return t
|
||
|