generating an AVRO schema from a JSON document

Question

Is there any tool able to create an AVRO schema from a \'typical\' JSON document.

For example:

{
\"records\":[{\"name\":\"X1\",\"age\":2},{\"name\":\         


        

Answer 1

You can achieve that easily using Apache Spark and python. First download the spark distribution from http://spark.apache.org/downloads.html, then install avro package for python using pip. Then run pyspark with avro package:

./bin/pyspark --packages com.databricks:spark-avro_2.11:3.1.0

and use the following code (assuming the input.json files contains one or more json documents, each in separate line):

import os, avro.datafile

spark.read.json('input.json').coalesce(1).write.format("com.databricks.spark.avro").save("output.avro")
avrofile = filter(lambda file: file.startswith('part-r-00000'), os.listdir('output.avro'))[0]

with open('output.avro/' + avrofile) as avrofile:
    reader = avro.datafile.DataFileReader(avrofile, avro.io.DatumReader())
    print(reader.datum_reader.writers_schema)

For example: for input file with content:

{'string': 'somestring', 'number': 3.14, 'structure': {'integer': 13}}
{'string': 'somestring2', 'structure': {'integer': 14}}

The script will result in:

{"fields": [{"type": ["double", "null"], "name": "number"}, {"type": ["string", "null"], "name": "string"}, {"type": [{"type": "record", "namespace": "", "name": "structure", "fields": [{"type": ["long", "null"], "name": "integer"}]}, "null"], "name": "structure"}], "type": "record", "name": "topLevelRecord"}