If you already have a Date in JS that you need to get into Elm, then
sending it as an ISO string will certainly work. But another, more direct
way to pass a date representation through a port is to pass it as a number,
using the getTime
<https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Date/getTime>
method
in JS. In Elm, you can decode it as a Float and then convert it to a Date
with Date.fromTime
<http://package.elm-lang.org/packages/elm-lang/core/5.1.1/Date#fromTime>.
There isn't a *Json.Decode.date*, likely because JSON doesn't describe a
standard way to encode dates. In Elm, the idea of Json encoding/decoding
extends to all conversions between JS types and Elm types, which is nice in
that it gives us a unifying concept, but it does leave out the ability to
pass Date values to and from Elm, without first converting them to a
JSON-representable type.
Justin
On Sunday, January 29, 2017 at 2:47:43 PM UTC-5, Mickey Vashchinsky wrote:
>
> Looks like you already have Date and not String.
>
> I am pretty new to Elm myself and I couldn't find a way to decodeValue of
> Date, but, I think as a workaround, on JavaScript side before sending the
> json
> through port, you could convert your Date fields to String with:
>
> myJson.date = myJson.date.toISOString()
>
> Hope it helps.
>
>
> On Sunday, January 29, 2017 at 4:55:51 PM UTC+2, fxmy wang wrote:
>>
>> Hi guys,
>> So I was trying to decode a field named date inside JSON as String but
>> without success. And the result is quite confusing.
>> Could anyone shed some light on me?
>>
>> JSON:
>>
>> [{"author":{"type":"full","displayName":"fxmy","url":"https://github.com/fxmy","picture":"https://avatars.githubusercontent.com/u/3283415?v=3&s=73"},"content":"another
>> test","date":"2017-01-26T03:43:57.190Z"}]
>>
>> Json.Encode.Value that comes through port ( via Debug.log) :
>>
>> value: { 0 = { author = { type = "full", displayName = "fxmy", url =
>> "https://github.com/fxmy";, picture =
>> "https://avatars.githubusercontent.com/u/3283415?v=3&s=73"; }, content =
>> "another test", date = <Thu Jan 26 2017 11:43:57 GMT+0800 (CST)> } }
>>
>> When trying to decode date field as String I got this,
>> Result after calling Json.Decode.decodeValue ( via Debug.log) :
>>
>> Err "Expecting a String at _[0].date but instead got:
>> \"2017-01-26T03:43:57.190Z\""
>>
>> What am I doing wrong?
>>
>> Cheers.
>>
>>
>
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