Encountering this JSON deserialization error message: *Cannot construct instance of `org.example.bat...

# jackson-kotlin

[napperley]

Encountering this JSON deserialization error message: Cannot construct instance of org.example.battery_info.model.http.SensorDataTimestampRangeBody (although at least one Creator exists): no String-argument constructor/factory method to deserialize from String value ('{"owner":"Joe Bloggs","site":"House","timestampRange":{"endDay":3,"endHour":12,"endMinute":0,"endMonth":5,"endYear":2019,"startDay":2,"startHour":12,"startMinute":0,"startMonth":5,"startYear":2019}}'

Upon inspection the JSON structure matches correctly to the data classes yet deserialization fails when the Android client makes a HTTP request. The CLI client works fine without any issues. Is there a way to fix the JSON deserialization issue? Is the issue related to this GitHub issue ( https://github.com/FasterXML/jackson-module-kotlin/issues/91 )?

[napperley]

SensorDataTimestampRangeBody model:

data class SensorDataTimestampRangeBody(val owner: String, val site: String, val timestampRange: TimestampRange)

[napperley]

TimestampRange model:

data class TimestampRange(
    val startYear: Int,
    val startMonth: Int,
    val startDay: Int,
    val endYear: Int,
    val endMonth: Int,
    val endDay: Int,
    val startHour: Int,
    val startMinute: Int,
    val endHour: Int,
    val endMinute: Int
)

[mp]

Jackson is complaining that you’re trying to deserialize from a String.

[mp]

The json structure is probably fine but it’s inside a String — see the quotes in the error message around the curlies

[mp]

Perhaps content type is not set on the Android client?

[napperley]

Discovered with the Android client that it is producing a String instead of a Object. I have rectified the issue and have had no issues since 😄.