Hello, I have a question regarding the retrieval ...

# apollo-kotlin

[gaetan]

Hello,

I have a question regarding the retrieval of JSON fields.

I am in the context of data extraction from a GraphQL API. The data is read via Apollo-Kotlin before being stored in a BigQuery database. The API has a generic field that allows storing user data that may not be known in advance. This field is defined as being of JSON type. I want to retrieve the data without any transformation to process it later.

Is it possible to retrieve the JSON string without any transformation?

Any help is truly appreciated,

[mbonnin]

It depends how your json field is transmitted over the wire. Usually JSON custom scalars are transmitted like so:

{
  "data": {
    "jsonField": {
      "key": "value"
    }
  }
}

[mbonnin]

In that case, you can use AnyAdapter to map it to a Kotlin Any that you can cast to Map<String, Any?>

[mbonnin]

The other solution is if it's ttansmitted like so:

{
  "data": {
    "jsonField": "{ \"key\": \"value\" }"
  }
}

(less common)

[mbonnin]

In that case, you can use StringAdapter to map it to a Kotlin String

[mbonnin]

Actually you don't need to use AnyAdapter or StringAdapter because the runtime will do this by default and present you with an Any type that you can either cast to a Map or String

[mbonnin]

If you want to serialize a Map back to JSON, you can use something like so:

buildJsonString { 
    AnyAdapter.toJson(this, CustomScalarAdapters.Empty, map)
  }

[mbonnin]

But you have to parse the JSON in all cases because the parser needs to know where the JSON field stops

[gaetan]

Thanks a lot Martin, I will try that.