I m deserializing a Date from a String using a custom KSeria | Serialization | Kotlinlang

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#serialization

r

Russell Cullen

2 years ago

I'm deserializing a

Date?

from a

String?

using a custom

KSerializer<Date>

and it's working great, until the 3rd party API I'm using sends an empty string instead of null as expected. Is there a way to map this empty case to a null Date instead of a dummy-Date? It seems something like

KSerializer<Date?>

is not supported, is that correct?

Fudge

Fudge

2 years ago

To get a nullable serializer of something do .nullable like .list

(Actually I’m not sure if this was pushed yet, if not you can wrap your date serializer into a NullableSerializer instead)

r

Russell Cullen

2 years ago

Well the problem isn't just nullability, nulls map to each other fine. But during deserialization I want to map an empty string to a null date, but

KSerializer<Date>

does not allow null return types. (And

KSerializer<Date?>

does not match the

Date?

types on my class for some reason) How can I use

.nullable

in an annotation? I assumed this was used under the hood already for me since my Date types are nullable. At the end, I would like a deserializer that does the following:

String?

->

Date?

where

null

or

""

maps to

null: Date?

Kroppeb

Kroppeb

2 years ago

if you want to decode a nullable element the serializer calls the

decodeNullableElement

of the compositedecoder which will most likely call

decodeNotNullMark()

on the decoder which will return false if the next value is null.

So unless you have custom decoder I don't see how you'd fix it.

r

Russell Cullen

2 years ago

Yeah that's what I figured, thanks! I have a workaround right now and just pick a reasonable default.

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