LogicalType does not get ingested into the schema when using Type.forSchema()

[jtmarks6]

I am trying to load a schema that has a timestamp field that uses logicalType: 'timestamp-millis' and can not get the logicalType to stay in the schema when loaded.

Here is a test case I wrote in my repo to show the issue:

it.only(`logicalType should be loaded into schema`, async () => {
    const avsc = require('avsc')
    const schema = {
        type: 'record',
        name: 'record_name',
        fields: [
            {
                name: 'timestamp_field',
                type: [
                    'null',
                    { type: 'long', logicalType: 'timestamp-millis' },
                ],
                default: null,
            },
        ],
        namespace: 'name.space',
    }

    const expectedSchema = {
        type: 'record',
        fields: [
            {
                name: 'timestamp_field',
                type: [
                    'null',
                    { type: 'long', logicalType: 'timestamp-millis' },
                ],
            },
        ],
        name: 'name.space.record_name',
    }

    const type = avsc.Type.forSchema(schema)
    expect(type.schema()).to.equal(expectedSchema)
})

type.schema() outputs this schema:

{
    type: 'record',
    fields: [
        {
            name: 'timestamp_field',
            type: [
                'null',
                'long'
            ],
        },
    ],
    name: 'name.space.record_name',
}

[mtth]

Hi @jtmarks6. By default type.schema() returns the type's canonical schema. You can set the exportAttrs option to include other attributes, including logical type.

[urugator]

Hi, maybe there is a bug? The following:

const type = avro.Type.forSchema(  
  {
    namespace: 'ns',
    type: 'record',
    name: 'foo',
    version: 1,
    fields: [
      {
        name: 'bar',
        type: { type: 'long', logicalType: 'local-timestamp-millis' },
      },
    ],
  },
);
console.log(type.schema({ exportAttrs: true }));

produces

{
  name: 'ns.foo',
  type: 'record',
  fields: [ { name: 'bar', type: 'long' } ]
}

[mtth]

@urugator - this is WAI, actually. I forgot to mention that the logical type must be used. Here there are no constructors passed in when parsing the schema, so the logicalType key is ignored. Unknown keys are similarly ignored - if you want the original schema used to create a type, you will need to keep a reference to it separately. This design was chosen to avoid inconsistencies due to mutability.

[urugator]

I see, thank you. To elaborate a bit, I attempted to use @kafka/confluent-schema-registry to obtain the original schema from registry, but unfortunately it returns directly the avsc.Type instance. I tried to work around it using .schema(), but in the end I ditched the library and call the API directly.