从JSON文档生成AVRO模式

Question

是否有任何工具能够从"典型的"JSON文档创建AVRO模式.

例如:

{
"records":[{"name":"X1","age":2},{"name":"X2","age":4}]
}

我找到了http://jsonschema.net/reboot/#/,它生成了一个' json-schema '

{
  "$schema": "http://json-schema.org/draft-04/schema#",
  "id": "http://jsonschema.net#",
  "type": "object",
  "required": false,
  "properties": {
    "records": {
      "id": "#records",
      "type": "array",
      "required": false,
      "items": {
        "id": "#1",
        "type": "object",
        "required": false,
        "properties": {
          "name": {
            "id": "#name",
            "type": "string",
            "required": false
          },
          "age": {
            "id": "#age",
            "type": "integer",
            "required": false
          }
        }
      }
    }
  }
}

但我想要一个AVRO版本.

Answer 1

您可以使用Apache Spark和python轻松实现这一目标。首先从http://spark.apache.org/downloads.html下载spark发行版，然后avro使用来安装python软件包pip。然后使用avro软件包运行pyspark：

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

并使用以下代码（假设input.json文件包含一个或多个json文档，每个文档位于单独的行中）：

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)

例如：对于具有内容的输入文件：

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

该脚本将导致：

{"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"}