feat: add support for deleting state attributes, implements the '__delitem__' method on the 'State class'

[Amar3x3]

Attribute Deletion: Implements the delitem method, allowing users to remove an attribute from the session state using the del callback_context.state['attribute-id'] syntax. This resolves the AttributeError: delitem and directly addresses feature request #2564 .

Implementation Details
delitem(key): The method checks for the key's existence and removes it from both the base _value and the pending _delta dictionaries to ensure the state is consistent. It raises a KeyError if the key is not found.

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[gemini-code-assist]

Summary of Changes

Hello @Amar3x3, I'm Gemini Code Assist¹! I'm currently reviewing this pull request and will post my feedback shortly. In the meantime, here's a summary to help you and other reviewers quickly get up to speed!

This pull request introduces the capability to delete attributes from the State class, resolving a long-standing issue where attempts to remove state entries would result in an AttributeError. By implementing the __delitem__ method, users can now seamlessly remove attributes using standard Python syntax, enhancing the flexibility and manageability of session state. The changes ensure that deletions are consistently applied across the state's internal data structures and are thoroughly validated with new unit tests.

Highlights

• Enabling Attribute Deletion: The core change is the addition of the __delitem__ magic method to the State class. This method enables the use of Python's built-in del keyword to remove attributes from the session state, addressing a previously reported AttributeError and feature request #2564.
• Ensuring State Consistency: The implementation of __delitem__ ensures data consistency by checking for and removing the specified key from both the _value (base state) and _delta (pending changes) dictionaries within the State object. This prevents orphaned or inconsistent state entries.
• Comprehensive Test Coverage: New unit tests have been added to thoroughly validate the __delitem__ functionality, including scenarios for successful deletion from both internal dictionaries and proper KeyError handling for non-existent keys. An additional test file was created to specifically reproduce the original AttributeError.

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[adk-bot]

Response from ADK Triaging Agent

Hello @Amar3x3, thank you for creating this PR!

It looks like the CLA check has failed. Please make sure to sign the Contributor License Agreement (CLA) for your contribution to be accepted.

In addition, could you please add a testing plan section to your PR description to talk about how you tested your changes? This will help reviewers to review your PR more efficiently.

Thanks!

[gemini-code-assist]

Code Review

This pull request successfully implements the __delitem__ method on the State class, allowing for attribute deletion. The implementation is correct and is accompanied by a good set of unit tests in test_state.py.

My review includes a few suggestions:

• A simplification of the __delitem__ implementation for better readability and conciseness.
• A recommendation to remove the temporary test script test_delitem_issue.py as its purpose is now covered by the formal unit tests.
• An enhancement to the new unit tests to cover an additional edge case where a key exists in both internal dictionaries.

Overall, this is a solid contribution that addresses the feature request.

[Amar3x3]

@DeanChensj delete state attributes is added, with unit test cases, please look into it and let me know if any improvements and changes required

[PaveLuchkov]

Hi! I have similar PR for the same functionallity. Your PR has some problems because deleting state key is not enought. You can check comments of my PR I've faced the same problem. If you want you can help me write tests! :)