Any recommendations for handling a GraphQL query that return

Question

Any recommendations for handling a GraphQL query that returns a response field with type of `GraphQLJSONObject` from <https github com taion graphql type json> Is it just a case of defining a custom type adapter here If so are they any known adapters baked already for turning this into a map of primitives

mbonnin · Answer

Hi wave Unfortunately we do not support mapping custom scalar to generic types see <https github com apollographql apollo kotlin issues 3243>

mbonnin · Answer

2 solutions 1 you can wrap your map into a custom class ```class MyJsonObject val fields Map lt String Any gt ``` register the mapping ```apollo mapScalar JSONObject com example MyJsonObject ``` register the adapter ```apolloClientBuilder addCustomScalarAdapter JSONObject type object Adapter lt MyJsonObject gt override fun fromJson reader JsonReader customScalarAdapters CustomScalarAdapters MyJsonObject return MyJsonObject reader readAny as Map lt String Any gt override fun toJson writer JsonWriter customScalarAdapters CustomScalarAdapters value MyJsonObject writer writeAny value fields ```

mbonnin · Answer

2 you can use the builtin `AnyAdapter` ```apollo mapScalarToKotlinAny JSONObject ```

mbonnin · Answer

2 is simpler but will requires casting to `Map lt String Any gt ` when using such fields

Stylianos Gakis · Answer

are the available adapters right now if you re curious Which note that I only found in the migration file in the docs Maybe they deserve a spot in the normal docs as well for someone who isn t migrating from 2 x I couldn t find them mentioned there did I miss it We have the exact same use case and we re doing the mapping to and from a JSONObject from a scalar we call JSONString Then at least we get to work with JSONObject which I personally don t love but it seems to work for us

mbonnin · Answer

The doc for Apollo provided adapters is <https www apollographql com docs kotlin essentials custom scalars apollo provided adapters|there> Moving forward we ll certainly want to encourage using the Gradle options directly `mapScalarToKotlinAny ` etc

mbonnin · Answer

```return JSONObject reader nextString ``` This only works if the Json is encoded as a Json string right so there is some wrapping I though the GraphQL `JSONObject` didn t require wrapping

mbonnin · Answer

So for a schema like this ```scalar JSONObject type Query json JSONObject ``` This is a valid response ``` json key value ``` But not this ``` json key value ```

Stylianos Gakis · Answer

Thanks I completely missed it What do you mean by using the gradle options directly To provide a custom adapter you d still have to register the adapter in code and sometimes the existing ones like mapScalarToKotlinAny etc don t suffice for our custom scalars I probably misunderstood something gt This only works if the Json is encoded as a Json string right Yes our JSONString scalar is used exactly like this the backend sends a proper json string in there It seems to work when there s no indentation either <https github com HedvigInsurance android blob f02fa9b3d858cfeb3e3e8212984141ed1c5c3f56 app src test java com hedvig app apollo EmbarkStoryQueryParsingTest kt L261|here> What am I misunderstanding this time smile

mbonnin · Answer

gt sometimes the existing ones like mapScalarToKotlinAny etc don t suffice for our custom scalars It does now slightly smiling face < bod> added the possibility to pass the constructor object adapter to `mapScalar` so that it is baked in the codegen ```fun mapScalar graphQLName String targetName String expression String ``` Can be used like so ```mapScalar Date com example Date com example DateAdapter ``` where `DateAdapter` is an object implementing `Adapter lt Date gt `

mbonnin · Answer

`mapScalarToKotlinAny ` will bake the builtin `AnyAdapter` in the codegen Obviously you still need `apollo adapters` in the classpath we could add it automatically but we have decided not to touch the dependencies for `apollo api` so it might be weird to do it for `apollo adapters`

mbonnin · Answer

gt Yes our JSONString scalar is used exactly like this the backend sends a proper json string in there This is very fine but I think this is not what <https github com taion graphql type json> is about I might be mistaken though Because there s no real spec for this different implementations do things differently

Stylianos Gakis · Answer

One thing I was wondering about providing the path to the adapter in the gradle file to avoid submitting it in runtime was what happens when these adapters are in a different module Currently we have one module which simply contains the graphql s files and the apollo configuration in its gradle config With that said however I guess I could move the adapters in that module and it d work Hmm probably is a good idea

mbonnin · Answer

Yea they need to be available when compiling the models

Stylianos Gakis · Answer

Yeah maybe a bit weird to then have to add Adyen as a dependency in our apollo only module in order to get the adapter baked in without having to provide it as a custom scalar adapter Since we re also serializing deserializing an object coming from their SDK <https github com HedvigInsurance android blob 7f7a86f5f56fb03d96ba2fb02cebc7dd33b24a9e app src main java com hedvig app util apollo adapter PaymentMethodsApiResponseAdapter kt L11 L23|here> But at the same time maybe this is fine since we want apollo to deal with that type it s fine for the module to depend on that sdk just to bring in that type

Stylianos Gakis · Answer

About that graphql type json spec yeah I wasn t even aware it exists and it s possible my backend team didn t either and we are doing our own thing for this problem smile

mbonnin · Answer

On the plus side you save a HashMap lookup for each custom scalar field by baking them We have never really benchmarked this but that could be an argument

james · Answer

Thankyou both Awesome discussion to wake up to I ve opted to go for your wrapped solution `class MyJsonObject val fields Map lt String Any gt ` for now and it works a treat Glad I posted