InfluxDB 2 / influxdb-client-java: Long data is written but String value is read. ClassCastException occurred

Question

InfluxDB v2.5.1

influxdb-client-java 6.7.0

Java POJO

@Data
@Builder
@NoArgsConstructor
@AllArgsConstructor
@Measurement(name = "my_measurement")
public class MyMeasurement {

    @Column(timestamp = true)
    private Instant time;

    @Column(name = "my_tag", tag = true)
    private Long myTag;

    @Column(name = "value")
    private Integer value;

}

Write

influxDBClient.getWriteApiBlocking().writeMeasurements(WritePrecision.NS,
        IntStream.range(0, 1000)
                .mapToObj(i -> MyMeasurement.builder()
                        .time(Instant.now())
                        .myTag(Math.abs(new Random().nextLong()))
                        .value(Math.abs(new Random().nextInt()))
                        .build())
                .collect(Collectors.toList()));

Read

influxDBClient.getQueryApi()
    .query("from(bucket: \"mybucket\") |> range(start: -1d) |> filter(fn: (r) => r[\"_measurement\"] == \"my_measurement\")", MyMeasurement.class);

The reading statement throws InfluxException

com.influxdb.exceptions.InfluxException: Class 'MyMeasurement' field 'myTag' was defined with a different field type and caused a ClassCastException. The correct type is 'java.lang.String' (current field value: '1000816197908726879').

Answer 1

1. First of all tag in influxdb always is string link
2. Secondly when you get it from influx using influx-client it get it from influxdb as a String and cannot cast to Long. (because under hood java influx client uses long.class.isAssignableFrom(fieldType)) and String is not assiganble for Long. Possible solution is to use String for tags in your POJO.