Celos/avro-json-decoder

JSON decoder for AVRO that infers default values

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Step 1. Add the JitPack repository to your build file

Add it in your root settings.gradle at the end of repositories:

	dependencyResolutionManagement {
		repositoriesMode.set(RepositoriesMode.FAIL_ON_PROJECT_REPOS)
		repositories {
			mavenCentral()
			maven { url 'https://jitpack.io' }
		}
	}

Add it in your settings.gradle.kts at the end of repositories:

	dependencyResolutionManagement {
		repositoriesMode.set(RepositoriesMode.FAIL_ON_PROJECT_REPOS)
		repositories {
			mavenCentral()
			maven { url = uri("https://jitpack.io") }
		}
	}

Add to pom.xml

	<repositories>
		<repository>
		    <id>jitpack.io</id>
		    <url>https://jitpack.io</url>
		</repository>
	</repositories>

Add it in your build.sbt at the end of resolvers:

 
    resolvers += "jitpack" at "https://jitpack.io"

Add it in your project.clj at the end of repositories:

 
    :repositories [["jitpack" "https://jitpack.io"]]

Step 2. Add the dependency

	dependencies {
		implementation 'com.github.celos:avro-json-decoder:1.2'
	}
	dependencies {
		implementation("com.github.celos:avro-json-decoder:1.2")
	}
	<dependency>
	    <groupId>com.github.celos</groupId>
	    <artifactId>avro-json-decoder</artifactId>
	    <version>1.2</version>
	</dependency>

                            
    libraryDependencies += "com.github.celos" % "avro-json-decoder" % "1.2"
        
        

                            
    :dependencies [[com.github.celos/avro-json-decoder "1.2"]]

Readme

avro-json-decoder Build Status

JSON decoder for AVRO that infers default values. Based on org.apache.avro.io.JsonDecoder from <a href="https://github.com/apache/avro">AVRO</a> 1.8.2 and org.apache.avro.io.ExtendedJsonDecoder by <a href="https://github.com/zolyfarkas/avro">zolyfarkas</a>.

why

Given this schema (in AVRO IDL)

record User {
  string username;
  union {null, string} name = null;
}

this record is valid and will be decoded properly

{"username":"user1","name":null}

whereas this record

{"username":"user1"}

will produce something like

org.apache.avro.AvroTypeException: Expected field name not found: name
	at org.apache.avro.io.JsonDecoder.doAction(JsonDecoder.java:495)
	at org.apache.avro.io.parsing.Parser.advance(Parser.java:88)
	at org.apache.avro.io.JsonDecoder.advance(JsonDecoder.java:157)
	at org.apache.avro.io.JsonDecoder.readIndex(JsonDecoder.java:447)
	...

or

org.apache.avro.AvroTypeException: Expected start-union. Got END_OBJECT
	at org.apache.avro.io.JsonDecoder.error(JsonDecoder.java:698)
	at org.apache.avro.io.JsonDecoder.readIndex(JsonDecoder.java:441)
	at org.apache.avro.io.ResolvingDecoder.doAction(ResolvingDecoder.java:290)
	at org.apache.avro.io.parsing.Parser.advance(Parser.java:88)
        ...

The decoder allows decoding JSON that doesn't specify optional values, provided they have defaults.

how

Replace

Decoder decoder = DecoderFactory.get().jsonDecoder(SCHEMA, INPUT_STREAM_OR_STRING);

with

Decoder decoder = new ExtendedJsonDecoder(SCHEMA, INPUT_STREAM_OR_STRING);

and pass it to your reader, as usual:

SpecificDatumReader<T> reader = new SpecificDatumReader<>(SCHEMA_OR_CLASS);
reader.read(null, decoder);