How to get all data from a message segment with Databricks Labs Smolder-CodePudding

I know that you can use the provided helper functions to retrieve subfields from message segments for example

val nameDf = df.select(segment_field("PID", 4).alias("name"))

Is there a way I can extract the entire message segment ("PID") instead of having to put in an index for each subfield?

PID|||d40726da-9b7a-49eb-9eeb-e406708bbb60||Heller^Keneth||||||140 Pacocha Way Suite 52^^Northampton^Massachusetts^^USA

CodePudding user response：

segment_field as implemented here is a helper method to extract a single value given the index.

  /**
   * Extracts a field from a message segment.
   * 
   * @param segment The ID of the segment to extract.
   * @param field The index of the field to extract.
   * @param segmentColumn The name of the column containing message segments.
   *   Defaults to "segments".
   * @return Yields a new column containing the field of a message segment.
   * 
   * @note If there are multiple segments with the same ID, this function will
   *   select the field from one of the segments. Order is undefined.
   */
  def segment_field(segment: String,
    field: Int,
    segmentColumn: Column = col("segments")): Column = {

    filter(segmentColumn, s => s("id") === lit(segment))
      .getItem(0)
      .getField("fields")
      .getItem(field)
  }

However, if you are interested in extracting all the field values regardless of index you may replicate this behaviour as

import org.apache.spark.sql.Column
import org.apache.spark.sql.functions._


  def segment_fields(segment: String,
    segmentColumn: Column = col("segments")): Column = {

    filter(segmentColumn, s => s("id") === lit(segment))
      .getItem(0)
      .getField("fields")
  }

and use as such

val nameDf = df.select(segment_fields("PID").alias("values"))

You may then extract or transform the data as desired.