[FLINK-35112][python] Fix membership for Row class PyFlink

[wzorgdrager]

What is the purpose of the change

This pull request adds support for a membership check for field names in a Row in PyFlink. If field names are not defined, it will check membership in the values. For example:

user_row = Row(name="Alice", age=22)
print("name" in user_row)
# Evaluates to True

user_row = Row("Alice", 22)
print("Alice" in user_row)
# Evaluates to True

This change is more in line with how dictionaries behave in Python.

Brief change log

• Change in behaviour for Row class.
  • If field names are defined, KEY in row will check if KEY exists in field names.
  • If field names do not exist, KEY in row will check if KEY exists in field values (current behaviour).

Verifying this change

This change is a trivial rework / code cleanup without any test coverage.

Does this pull request potentially affect one of the following parts:

• Dependencies (does it add or upgrade a dependency): no
• The public API, i.e., is any changed class annotated with @Public(Evolving): no
• The serializers: no
• The runtime per-record code paths (performance sensitive): no
• Anything that affects deployment or recovery: JobManager (and its components), Checkpointing, Kubernetes/Yarn, ZooKeeper: no
• The S3 file system connector: no

Documentation

• Does this pull request introduce a new feature? no
• If yes, how is the feature documented? not applicable

[flinkbot]

CI report:

• 2e05efe Azure: SUCCESS

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[jectpro7]

The enhancement is great. I have one comment, the _fields could be a None by invoking set_field_names. So it should return False in this case.

[wzorgdrager]

so then the question is, if _fields is None do we want to fallback and do a membership check for the values or always just return False?

[dianfu]

@wzorgdrager Thanks a lot for the PR. Personally I prefer to fallback to check for the values if _fields is None.

[wzorgdrager]

@dianfu I agree. I added the change now.