object decoder for more than 8 fields

[uehaj]

I can't find the easy &simple way of object decoder, for the object which have more than 8 fields in current Elm's Json.Decode package. This PR provides helper functions for define generic decoder for object which have any number of fields.

I think this PR is not perfect, because:

• For touple(1-8), we can provide similar helper functions.
• object 1-8 can be redefine to use this helpers in theory.
• no test. simple test code for this PR are: http://share-elm.com/sprout/54ead339e4b09711f39c2d1f

If the direction is ok, I can additional tweak for this PR.

[jvoigtlaender]

@uehaj, is this issue still relevant for you? Discussion of decoding objects with more than 8 fields can be found here.

Does that work for you? Can we close the PR here?

[jvoigtlaender]

@uehaj, is this issue still relevant for you? Discussion of decoding objects with more than 8 fields can be found here.

Does that work for you? Can we close the PR here?

[uehaj]

@jvoigtlaender, Thanks for notification.
I tried:

import Json.Decode as Decode
import Json.Decode exposing (..)
import Text exposing (fromString)
import Graphics.Element exposing (flow,down,show)
import List


type alias DomMouseEvent =
  { screenX : Int
  , screenY : Int
  , clientX : Int
  , clientY : Int
  , ctrlKey : Bool
  , shiftKey : Bool
  , altKey : Bool
  , metaKey : Bool
  , button : Int
  , buttons : Int
  }

andMap : Decoder (a -> b) -> Decoder a -> Decoder b
andMap = Decode.object2 (<|)

decodeDomMouseEvent : Decoder DomMouseEvent
decodeDomMouseEvent =
  DomMouseEvent
    `Decode.map` Decode.int
    `andMap` Decode.int
    `andMap` Decode.int
    `andMap` Decode.int
    `andMap` Decode.bool
    `andMap` Decode.bool
    `andMap` Decode.bool
    `andMap` Decode.bool
    `andMap` Decode.int
    `andMap` Decode.int

main = flow down
       [ show <| decodeString Decode.int "3"
       , show <| decodeString (list string) "[\"abc\",\"def\"]"
       , show <| decodeString decodeDomMouseEvent "{\"screenX\":3, \"screenY\":3, \"clientX\":3, \"clientY\":3, \"ctrlKey\":true, \"shiftKey\":true, \"altKey\":true, \"metaKey\":true, \"button\":3, \"buttons\":3}"
       ]

on Elm Platform 0.15.1 but get following error:

Ok 3
Ok ["abc","def"]
Err ("expecting an Int but got {\"screenX\":3,\"screenY\":3,\"clientX\":3,\"clientY\":3,\"ctrlKey\":true,\"shiftKey\":true,\"altKey\":true,\"metaKey\":true,\"button\":3,\"buttons\":3}")

Something wrong? or bad usage?

[uehaj]

@jvoigtlaender, Thanks for notification.
I tried:

import Json.Decode as Decode
import Json.Decode exposing (..)
import Text exposing (fromString)
import Graphics.Element exposing (flow,down,show)
import List


type alias DomMouseEvent =
  { screenX : Int
  , screenY : Int
  , clientX : Int
  , clientY : Int
  , ctrlKey : Bool
  , shiftKey : Bool
  , altKey : Bool
  , metaKey : Bool
  , button : Int
  , buttons : Int
  }

andMap : Decoder (a -> b) -> Decoder a -> Decoder b
andMap = Decode.object2 (<|)

decodeDomMouseEvent : Decoder DomMouseEvent
decodeDomMouseEvent =
  DomMouseEvent
    `Decode.map` Decode.int
    `andMap` Decode.int
    `andMap` Decode.int
    `andMap` Decode.int
    `andMap` Decode.bool
    `andMap` Decode.bool
    `andMap` Decode.bool
    `andMap` Decode.bool
    `andMap` Decode.int
    `andMap` Decode.int

main = flow down
       [ show <| decodeString Decode.int "3"
       , show <| decodeString (list string) "[\"abc\",\"def\"]"
       , show <| decodeString decodeDomMouseEvent "{\"screenX\":3, \"screenY\":3, \"clientX\":3, \"clientY\":3, \"ctrlKey\":true, \"shiftKey\":true, \"altKey\":true, \"metaKey\":true, \"button\":3, \"buttons\":3}"
       ]

on Elm Platform 0.15.1 but get following error:

Ok 3
Ok ["abc","def"]
Err ("expecting an Int but got {\"screenX\":3,\"screenY\":3,\"clientX\":3,\"clientY\":3,\"ctrlKey\":true,\"shiftKey\":true,\"altKey\":true,\"metaKey\":true,\"button\":3,\"buttons\":3}")

Something wrong? or bad usage?

[jvoigtlaender]

This works:

decodeDomMouseEvent : Decoder DomMouseEvent
decodeDomMouseEvent =
  DomMouseEvent
    `Decode.map` ("screenX" := Decode.int)
    `andMap` ("screenY" := Decode.int)
    `andMap` ("clientX" := Decode.int)
    `andMap` ("clientY" := Decode.int)
    `andMap` ("ctrlKey" := Decode.bool)
    `andMap` ("shiftKey" := Decode.bool)
    `andMap` ("altKey" := Decode.bool)
    `andMap` ("metaKey" := Decode.bool)
    `andMap` ("button" := Decode.int)
    `andMap` ("buttons" := Decode.int)

[jvoigtlaender]

This works:

decodeDomMouseEvent : Decoder DomMouseEvent
decodeDomMouseEvent =
  DomMouseEvent
    `Decode.map` ("screenX" := Decode.int)
    `andMap` ("screenY" := Decode.int)
    `andMap` ("clientX" := Decode.int)
    `andMap` ("clientY" := Decode.int)
    `andMap` ("ctrlKey" := Decode.bool)
    `andMap` ("shiftKey" := Decode.bool)
    `andMap` ("altKey" := Decode.bool)
    `andMap` ("metaKey" := Decode.bool)
    `andMap` ("button" := Decode.int)
    `andMap` ("buttons" := Decode.int)

[uehaj]

OK, it works for me, so cool, thanks!
I'll close this ticket.

[uehaj]

OK, it works for me, so cool, thanks!
I'll close this ticket.