The map union value you currently have can certainly carry another map type
within. Here's how you'd probably want to define it:
{
"name": "metadata",
"type": {
"type": "map",
"values": [
"null",
"int",
"float",
"string",
"boolean",
"long",
{
"type": "map",
"values": [
"null",
"int",
"float",
"string",
"boolean",
"long"
]
}
]
}
}
P.s. Its generally better to specify "null" as the first union type:
http://avro.apache.org/docs/current/spec.html#Unions
On Mon, 27 Mar 2017 at 16:47 Dag Stockstad <[email protected]> wrote:
> Hi Avro aficionados,
>
> I'm having trouble serializing a record with a nested map structure i.e. a
> map within a map. The record I'm trying to send has the following structure:
> {
> "event_type": "some_type",
> "data": {
> "id": "2f720f90-ea06-4248-a72e-01eea44981ed",
> "metadata": {
> "some_attr": "some_value",
> "some_map_with_unpredictable_name": {
> "some_attr": "some_value"
> }
> }
> }
> }
>
> And the schema is this:
> {
> "namespace": "org.example.event.avro",
> "type": "record",
> "name": "EventNotification",
> "fields": [{
> "name": "event_type",
> "type": "string"
> }, {
> "name": "data",
> "type": {
> "type": "record",
> "name": "EventData",
> "fields": [{
> "name": "id",
> "type": "string"
> }, {
> "name": "metadata",
> "type": {
> "type": "map",
> "values": [
> "int",
> "float",
> "string",
> "boolean",
> "long",
> "null"
> ]
> }
> }]
> }
> }]
> }
>
> The nested map (some_map_with_unpredictable_name) is causing problems
> (serialization error). Is there any way I can have another map as a value
> in the metadata map?
>
> Due to the nature of the system, I cannot 100% predict the structure of
> the metadata field. Can Avro accomodate these requirements or do I have to
> fall back on something such as JSON for this one?
>
> Help very appreciated (I'm a bit stuck).
>
> Kind regards,
> Dag
>
>
