Example Avro Schemas

Unions with null

Schemas using unions with null are simple. You just have to provide the data or omit in case of null, example:

@namespace("com.org.domain.examples")
protocol MyProtocol {
  record Picture {
    string url;
  }

  record Event {
    string name;
    union {null, Picture} picture = null;
  }
}

This schema can be satisfied with:

{
  "name": "John",
  "picture": {
    "url": "https://..."
  }
}

or

{
  "name": "John"
}

Unions with different records

Unions with different records can have ambiguities, the data can be the same but for a different type. In these cases you have to provide a wrapped union type, example:

@namespace("com.org.domain.examples")
protocol MyProtocol {
  record Picture {
    string url;
  }
  record Photo {
    string url;
  }

  record Event {
    string name;
    union {Picture, Photo} asset;
  }
}

This schema can be satisfied with:

{
  "name": "John",
  "asset": {
    "com.org.domain.examples.Picture": {
      "url": "https://..."
    }
  }
}

or

{
  "name": "John",
  "asset": {
    "com.org.domain.examples.Photo": {
      "url": "https://..."
    }
  }
}

Imported schemas

Schemas can be imported from other AVDL or AVSC files using the import declaration. Note that this only works using avdlToAVSCAsync, not avdlToAVSC. Import paths are defined relative to the AVDL file they are imported from. In the following example, person.avdl is located next to this AVDL file.

@namespace("com.org.domain.examples")
protocol MyProtocol {
  // AVDL files can be imported with "import idl"
  import idl 'person.avdl';

  // AVSC files can be imported with "import schema"
  import schema 'place.avsc';

  record Picture {
    string url;
  }

  record Event {
    Picture picture;
    com.org.domain.examples.Person person;
    com.org.domain.examples.Place place;
  }
}