Use custom classes and objects in a schema

You must define custom classes and objects inside a package if you want to use them in a notebook.

Written by saritha.shivakumar

Last published at: November 8th, 2022


You are trying to create a dataset using a schema that contains Scala enumeration fields (classes and objects). When you run your code in a notebook cell, you get a ClassNotFoundException error.

Sample code


object TestEnum extends Enumeration {
  type TestEnum = Value
  val E1, E2, E3 = Value

import spark.implicits._
import TestEnum._

case class TestClass(i: Int,  e: TestEnum) {}
val ds = Seq(TestClass(1, TestEnum.E1)).toDS

Error message

ClassNotFoundException: lineb3e041f628634740961b78d5621550d929.$read$$iw$$iw$$iw$$iw$$iw$$iw$TestEnum


The ClassNotFoundException error occurred because the sample code does not define the class and object in a package cell.


If you want to use custom Scala classes and objects defined within notebooks (in Apache Spark and across notebook sessions) you must define the class and object inside a package and import the package into your notebook.



Only class and object definitions can go in a package cell. Package cells cannot contain any function definitions, values, or variables.

Define the class and object

This sample code starts off by creating the package com.databricks.example. It then defines the object TestEnum and assigns values, before defining the class TestClass.


package com.databricks.example   // Create a package.
object TestEnum extends Enumeration {  // Define an object called TestEnum.
  type TestEnum = Value 
  val E1, E2, E3 = Value  // Enum values 
case class TestClass(i: Int, other:TestEnum.Value)   // Define a class called TestClass.


Classes defined within packages cannot be redefined without a cluster restart.

Import the package

After the class and object have been defined, you can import the package you created into a notebook and use both the class and the object.

This sample code starts by importing the com.databricks.example package that we just defined.

It then evaluates a DataFrame using the TestClass class and TestEnum object. Both are defined in the com.databricks.example package.


import com.databricks.example 
val df = sc.parallelize(Array(example.TestClass(1,(example.TestEnum.E1)))).toDS().show()

The DataFrame successfully displays after the sample code is run.

Shows the result of running the sample code using the custom class and object defined in the Scala package.

Please review the package cells (AWS | Azure | GCP) documentation for more information.

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