org.apache.avro.AvroTypeException: Unknown union branch

Question

I\'m using this Avro schema:

prices-state.avsc

{
    \"namespace\": \"com.company.model\",
    \"name\": \"Product\",
    \"type\":          


        

Answer 1

It was a namespace resolution issue. Take this simplified schema as an example:

test.avsc

{
    "name": "Product",
    "type": "record",
    "fields": [
        {
            "name": "order_by_item_price_by_item",
            "type": [
                "null",
                {
                    "type": "record",
                    "name": "markup_strategy",
                    "fields": [{
                        "name": "type",
                        "type": {
                            "name": "type",
                            "type": "enum",
                            "symbols": ["margin", "sale_price"]
                        }
                    }]
                }
            ]
        }
    ]
}

With the following JSON it validates just fine

test.json

{
    "order_by_item_price_by_item": {
        "markup_strategy": {
            "type": "margin"
        }
    }
}

Now if you were to add a namespace on top of your schema like

test.avsc

{
    "namespace": "test",
    "name": "Product",
    "type": "record",
    "fields": [
    ...

Then you would need to change your test.json as well or you'll get

Exception in thread "main" org.apache.avro.AvroTypeException: Unknown union branch markup_strategy

final_test.json

{
    "order_by_item_price_by_item": {
        "test.markup_strategy": {
            "type": "margin"
        }
    }
}

So when inside a union type and you're JSON encoding an Avro's named type (record, fixed or enum) where the user-specified name is used then the name of that type needs to be prepended with the namespace name too for resolution.

More on namespaces and JSON encoding.