[AVRO-3615] avro.schema.LogicalSchema does not compare correctly

• Type: Bug
• Status: Open
• Priority: Major
• Resolution: Unresolved
• Affects Version/s: 1.11.1
• Component/s: python
• Assignee: Unassigned
• Reporter: Martin Thøgersen
• Created: 23/Aug/22 07:35
• Updated: 23/Aug/22 07:35

Description

Say we create an avro logical type, e.g. Date:

{"type": "int", "logicalType": "date"} 

This schema can be created either by:
1) providing the above JSON representation to `avro.schema.parse()`.
2) call `make_logical_schema()`, which calls the underlying constructors.

However, the two instances are not considered equal. Because 2) does not set the `logicalType` in props, while 1) does.

Example:

import avro.constants
import avro.schema

logical_type = avro.constants.DATE
type_ = "int"
other_props = None
logical_schema = avro.schema.make_logical_schema(logical_type, type_, other_props or {})
print(logical_schema)
# Output: {"type": "int"}

expected_schema_json = '{"type": "int", "logicalType": "date"}'
expected_schema = avro.schema.parse(expected_schema_json)
print(expected_schema.__eq__(logical_schema)) # Compare by EqualByPropsMixin

# Output: False

Patch:
Below patch solves the issue for me. I'm unawave if this has unintended consequences or side effects, so please consider it a proposal rather than a given solution.

import avro.constants
import avro.schema

class LogicalSchemaPatch(avro.schema.PropertiesMixin):
    '''Patch for avro.Schema.LogicalSchema that inherits from PropertiesMixin
    to be able to set logicalType prop.
    This fixes class comparison for logical types (which is done by props).
    '''
    def __init__(self, logical_type):
        self.set_prop("logicalType", logical_type)
        self.logical_type = logical_type
avro.schema.LogicalSchema = LogicalSchemaPatch

logical_type = avro.constants.DATE
type_ = "int"
other_props = None
logical_schema = avro.schema.make_logical_schema(logical_type, type_, other_props or {})
print(logical_schema)
# Output: {"logicalType": "date", "type": "int"}

expected_schema_json = '{"type": "int", "logicalType": "date"}'
expected_schema = avro.schema.parse(expected_schema_json)
print(expected_schema.__eq__(logical_schema)) # Compare by EqualByPropsMixin

# Output: True