I want to decode a JSON object that looks like this: { "boxes" : { "1" : { "items" : { "1" : "pencil", "2" : "ball" }, }, "2" : { "items" : { "1" : "teapot", "2" : "spoon", "3" : "towel" } } } } I have no contro…

There are a couple different ways to model this data structure. When the keys of an object are dynamic, often you’ll want to model this in Elm with a Dict. However, it looks like they’re really just incrementing with each value so many these are better handled as a List. That’s up to you! If you go…

Thank you, stephenreddek, for your clear answer. I try to make it work using Json.Decode.keyValuePairs, but that raises a question: are you sure about the pipeline with Json.Decode.map ((key, value) -> value)? Elm doesn’t accept it: The argument is: Decoder (List ( String, String )) But (|>) …

Oh I’m sorry! You’re absolutely right. I missed the List.map inside the Decoder.map. I’ll update that in my answer. It’ll just be Json.Decode.keyValuePairs (Json.Decode.String) |> Json.Decode.map (List.map (\(key, value) -> value))

The other solution works (I think) but it does simply ignore the information encoded in the numbers and assumes that the fields are always decoded in the right order. This will probably be the case but I think strictly speaking the fields in an object are unordered (so the sender or JavaScript or El…

Thank you very much. It works like a charm! Still learning a lot. :smiley:

JSON decode unknown number of fields

Learn

iwtilma September 17, 2020, 9:04pm 7

Thanks for this solution too. For now I don’t need the order, but I will keep this in mind for future development.

Topic		Replies	Views
JSON decoding a list of objects, just get the keys Learn	5	1065	March 28, 2023
Decoding a JSON with no field names Learn	2	1693	January 16, 2022
Decode json object with warning for unhandled keys Request Feedback	2	1068	April 16, 2018
Tips on JSON decoding Learn	3	758	November 4, 2020
How to write a generic JSON decoder? Learn	12	2982	February 22, 2019

JSON decode unknown number of fields

Related topics