galarragas / avrohugger

Generate Scala case class definitions from Avro schemas

avrohugger

Schema-to-case-class code generation for working with Avro in Scala.

• avrohugger-core: Generate source code dynamically at runtime for evaluation at a later step
• avrohugger-tools: Generate source code at the command line with the avrohugger-tools jar.
• sbt-avrohugger: Generate source code at compile time with an sbt plugin.

Generates Scala case classes:

• Vanilla case classes (for use with Scalavro, Salat-Avro, gfc-avro, etc.)

• Case classes that implement SpecificRecordBase (for use with the Avro Specific API - Scalding, Spark, Avro, etc.).

Supports generating case classes with arbitrary fields of the following datatypes:

• INT -> Int
• LONG -> Long
• FLOAT -> Float
• DOUBLE -> Double
• STRING -> String
• BOOLEAN -> Boolean
• NULL -> Null
• MAP -> Map
• ENUM -> generate: scala.Enumeration, generate-specific: Java Enum
• BYTES -> //TODO
• FIXED -> //TODO
• ARRAY -> List
• UNION -> Option
• RECORD -> case class

Usage (for Scala 2.10 and 2.11)

####avrohugger-core

Get the dependency with:

"com.julianpeeters" % "avrohugger-core" %% "0.4.0"

Instantiate a Generator with Standard or SpecificRecord source formats. Then use

tToFile(input: T, outputDir: String): Unit

or

tToStrings(input: T): List[String]

where 'T' can be File, Schema, or String:

import avrohugger._
import format._

val schemaFile = new File("path/to/schema")
val generator = new Generator(SpecificRecord)
generator.fileToFile(schemaFile, "optional/path/to/output") // default output path = "target/generated-sources" 

####avrohugger-tools

Download the avrohugger-tools jar for Scala 2.10 or Scala 2.11(20MB!) and use it like the avro-tools jar Usage: [-string] (schema|protocol|datafile) input... outputdir:

• 'generate' generates Scala case class definitions java -jar /path/to/avrohugger-tools_2.11-0.4.0-assembly.jar generate schema user.avsc .

• 'generate-specific' generates case class definitions that extend SpecificRecordBase java -jar /path/to/avrohugger-tools_2.11-0.4.0-assembly.jar generate-specific schema user.avsc .

####sbt-avrohugger

Also available as an sbt plugin found here that adds a generate or generate-specific task to compile (an alternative to macros).

Future

• Support more avro types: fixed, bytes.

Testing

The scripted task runs all tests.

As per Doug Cutting's recommendations in the avro compiler tests, the string-based tests in test are augmented by scripted tests that generate and compile source that is run in de/serialization tests.

Credits

Depends on Avro and Treehugger. avrohugger-tools is based on avro-tools.

Contributors:

• Marius Soutier
• Paul Pearcy

Criticism is appreciated. Fork away, just make sure the tests pass before sending a pull request.