Pat McDonough created SPARK-16641:
-------------------------------------

             Summary: Add an Option to Create a Dataset With a Case Class, 
Ignoring Column Names (Using ordinal instead)
                 Key: SPARK-16641
                 URL: https://issues.apache.org/jira/browse/SPARK-16641
             Project: Spark
          Issue Type: Improvement
          Components: SQL
    Affects Versions: 2.0.0
            Reporter: Pat McDonough
            Priority: Minor


When working with a CSV that has no header row, there isn't a concise method to 
create a Dataset using a case class. An option to map fields by ordinal rather 
than field name would be great.

For example, given the following case class:

{code}
case class Part(partkey: Int,  name: String,  mfgr: String,  brand: String,  
_type: String,  size: Int,  container: String,  retailprice: Double,  comments: 
String)
{code}

I'd like to use the following:

{code}
val parts = spark.read.option("delimiter", "|").option("header", "false")
  .csv("dbfs:/databricks-datasets/tpch/data-001/part/").as[Part]
{code}

But that won't work because the field names  (_c0, _c1, _c2...) do not match 
the Case class field names.

Instead, I end up writing a bunch of extra conversion code in a map function.

{code}
val parts = spark.read.option("delimiter", "|").option("header", "false")
  .csv("dbfs:/databricks-datasets/tpch/data-001/part/")
  .map(p => 
    new part(p.getString(0).trim().toInt, p.getString(1), p.getString(2), 
p.getString(3), p.getString(4), p.getString(5).trim().toInt, p.getString(6), 
p.getString(7).trim().toDouble, p.getString(8)))
{code}

CC: [~rxin]



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