Use of an external java class as a type in an AVRO schema

Question

Is it possible to refer in an avsc file to a Java class already implemented?

My idea is to have something like:

{
    "namespace": "com.myCompany.myProject.schemas",
    "type": "record",
    "name": "SimpleTest",
    "fields": [
      {"name": "text","type": "string"},
      {"name": "myOtherObj","type": "com.myCompany.myProject.MyClass"}
      ]
}

where the field myOtherObj has as type the already defined java class MyClass that is already build.

Answer 1

My solution is: I defined a folder where I define a dummy version of the basic type MyClass, via the MyClass.avsc:

{
  "namespace": "com.myCompany.myProject.basicTypes",
  "type": "record",
  "name": "MyClass",
  "doc": "This is only a place-holder needed to let Avro compile correctly the schemas. The real implementation is provided in the java project",
  "fields": [
        {"name": "value", "type": "string"}
    ]
}

then, using the gradle plugin: https://github.com/commercehub-oss/gradle-avro-plugin, I build the avro class SimpleTest together with this. In this way Avro will create SimpleTest.java and MyClass.java and will correctly resolve their dependencies. Finally I remove from the classpath the implementation of MyClass.java created by the Avro plugin.

//remove the basicTypes as these are only place holder while the real implementation is somewhere else.
task removeBasicTypes {
    dependsOn compileJava
    doLast {
        println "Removing java files of all the basic types."
        //cleanup the generated java classes
        delete fileTree(dir: 'src/main/java/com/myCompany/myProject/basicTypes' , include: '**/*.java')
        //cleanup also the build folder that will be used to generate the jar file
        delete fileTree(dir: 'build/classes/java/main/com/myCompany/myProject/basicTypes' , include: '**/*.class')
    }
}

task generateAvro(type: com.commercehub.gradle.plugin.avro.GenerateAvroJavaTask) {
    source("$rootDir/basicTypes", "src/main/avro")
    outputDir = file("src/main/java")

    finalizedBy('removeBasicTypes')
}

The real implementation of this MyClass will be provided as a dependency or in the project where I include this generate SimpleTest.java file.