Issue with union types when sending Avro data

[haydursek]

I am sending avro data with a schema that has a union type defined as one of my fields. As below:
{ "name" : "applicationId", "type": ["null", "string"], "default": null }

When I send a json that contains an actual value for this field or whether it is missing from the json totally, which would be the null case, I am getting the error below :

APIError: HTTP 422 Conversion of JSON to Avro failed: Failed to convert JSON to Avro: Expected start-union. Got VALUE_STRING

Is this not a valid schema definition and valid use case ?

[alanhayes]

I'm getting the same issue. The error is not very helpful. In my case I've added a correlationId property to my AVRO schema: { "name" : "correlationId", "type": ["null", "string"], "default": null }

  Error sending message:  { Error
      at Object.<anonymous> (/Users/hayesa/dev/hmh-ids/node_modules/kafka-rest/lib/client.js:193:22)
      at Module._compile (internal/modules/cjs/loader.js:689:30)
      at Module._extensions..js (internal/modules/cjs/loader.js:700:10)
      at Object.require.extensions.(anonymous function) [as .js] (/Users/hayesa/dev/hmh-ids/node_modules/babel-watch/runner.js:63:7)
      at Module.load (internal/modules/cjs/loader.js:599:32)
      at tryModuleLoad (internal/modules/cjs/loader.js:538:12)
      at Function.Module._load (internal/modules/cjs/loader.js:530:3)
      at Module.require (internal/modules/cjs/loader.js:637:17)
      at require (internal/modules/cjs/helpers.js:22:18)
      at Object.<anonymous> (/Users/hayesa/dev/hmh-ids/node_modules/kafka-rest/index.js:18:14)
      at Module._compile (internal/modules/cjs/loader.js:689:30)
      at Module._extensions..js (internal/modules/cjs/loader.js:700:10)
      at Object.require.extensions.(anonymous function) [as .js] (/Users/hayesa/dev/hmh-ids/node_modules/babel-watch/runner.js:63:7)
      at Module.load (internal/modules/cjs/loader.js:599:32)
      at tryModuleLoad (internal/modules/cjs/loader.js:538:12)
      at Function.Module._load (internal/modules/cjs/loader.js:530:3)
      at Module.require (internal/modules/cjs/loader.js:637:17)
      at require (internal/modules/cjs/helpers.js:22:18)
      at Object.<anonymous> (/Users/hayesa/dev/hmh-ids/src/event/kafka.js:120:18)
      at Module._compile (internal/modules/cjs/loader.js:689:30)
      at babelWatchLoader (/Users/hayesa/dev/hmh-ids/node_modules/babel-watch/runner.js:50:13)
      at Object.require.extensions.(anonymous function) [as .js] (/Users/hayesa/dev/hmh-ids/node_modules/babel-watch/runner.js:61:7)
    name: 'APIError',
    status: 422,
    message:
     'Conversion of JSON to Avro failed: Failed to convert JSON to Avro: Expected start-union. Got VALUE_STRING',
    data:
     { error_code: 42203,
       message:
        'Conversion of JSON to Avro failed: Failed to convert JSON to Avro: Expected start-union. Got VALUE_STRING' } }```