Assertion on retrieving data from cassandra - scala

Question

i defined a class to map rows of a cassandra table:
case class Log(
val time: Long,
val date: String,
val appId: String,
val instanceId: String,
val appName: String,
val channel: String,
val originCode: String,
val message: String) {
}
i created an RDD to save all my tuples
val logEntries = sc.cassandraTable[Log]("keyspace", "log")
to see if all works i printed this:
println(logEntries.counts()) -> works, print the numbers of tuples retrieved.
println(logEntries.first()) -> exception on this line
java.lang.AssertionError: assertion failed: Missing columns needed by
com.model.Log: app_name, app_id, origin_code, instance_id
my columns of table log on cassandra are:
time bigint, date text, appid text, instanceid text, appname text, channel text, origincode text, message text
what's wrong?

Answer 1

As mentioned in cassandra-spark-connector docs, column name mapper has it's own logic for converting case class parameters to column names:
For multi-word column identifiers, separate each word by an underscore in Cassandra, and use the camel case convention on the Scala side.
So if you use case class Log(appId:String, instanceId:String) with camel-cased parameters, it will be automatically mapped to a underscore-separated notation: app_id text, instance_id text. It cannot be automatically mapped to appid text, instanceid text: you've missed an underscore.