Steven Aerts created AVRO-1777:
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Summary: Select best matching record when writing a union in python
Key: AVRO-1777
URL: https://issues.apache.org/jira/browse/AVRO-1777
Project: Avro
Issue Type: Improvement
Components: python
Affects Versions: 1.7.7
Reporter: Steven Aerts
Unlike javascript, python is not using wrapped types.
So when writing a union it needs to guess find out which type it will output.
At the moment it takes the last validating type.
I propose to take the type with the most matching fields.
So I propose to change in {{io.py}}:
{code}
# resolve union
index_of_schema = -1
for i, candidate_schema in enumerate(writers_schema.schemas):
if validate(candidate_schema, datum):
index_of_schema = i
if index_of_schema < 0: raise AvroTypeException(writers_schema, datum)
{code}
into
{code}
# resolve union
index_of_schema = -1
found_fields = -1
for i, candidate_schema in enumerate(writers_schema.schemas):
if validate(candidate_schema, datum):
nr_fields = candidate_schema.type in ['record', 'error', 'request'] and
len(candidate_schema.fields) or 1
if nr_fields > found_fields:
index_of_schema = i
found_fields = nr_fields
if index_of_schema < 0: raise AvroTypeException(writers_schema, datum)
{code}
If you want, I can create a pull request for this. And apply it both on py3 as
py.
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