Validating Json file with Avro Schema

Question

I'm trying to check if a Json string matches an Avro schema. I don't care about doing serialization of the data, just getting a bool result of isValidJson=true/false . I'll go with every golang library. I've tried to write something with this goavro lib, but it didn't work for me, maybe because I'm new to go like.

Desired pseudo code:

func main() {
    avroSchema := 
    `{"type":"record","name":"raw","namespace":"events","fields":[{"name":"my_int","type":["null","int"],"default":null},{"name":"my_string","type":["null","string"],"default":"null"},{"name":"my_string2","type":null}]}`
    jsonString := `{"my_int": 3, "my_string": "foo", "my_string2": null}`
    ok ;= isValidJson(jsonString, avroSchema)
}

Any idea how to implement the isValidJson(..) method?

Answer 1

Your schema json is invalid, it's missing the terminating } , so goavro.NewCodec returns an error.

Then your json string definitely doesn't match the schema, the json values must be a {type: value} .

You can use the following corrected schema and example string to validate it.

func main() {
  avroSchema := `
{ 
   "type":"record",
   "name":"raw",
   "namespace":"events",
   "fields":[
      {
         "name":"my_int",
         "type":[
            "null",
            "int"
         ],
         "default":null
      },
      {
         "name":"my_string",
         "type":[
            "null",
            "string"
         ],
         "default":null
      },
      {
         "name":"my_string2",
         "type":"null"
      }
   ]
}`
  codec, err := goavro.NewCodec(avroSchema)
  if err != nil {
    log.Fatalf("Codec error: %v", err)
  }

  jsonString := `{"my_int": {"int":3}, "my_string": {"string":"foo"}, "my_string2": null}`

  decoded, _, err := codec.NativeFromTextual([]byte(jsonString))
  if err != nil { 
    log.Fatalf("NativeFromTextual error: %v", err)
  } 
  log.Println("Decoded:", decoded)
} 

This prints:

Decoded: map[my_int:map[int:3] my_string:map[string:foo] my_string2:]