Merge https://github.com/google/adk-python/pull/3282
The `process_bind_param` and `process_result_value` methods in the `DynamicPickleType` class have been modified to handle MySQL dialect in addition to Spanner. This change ensures that pickled values are correctly processed for both database types.
**Please ensure you have read the [contribution guide](https://github.com/google/adk-python/blob/main/CONTRIBUTING.md) before creating a pull request.**
### Link to Issue or Description of Change
**1. Link to an existing issue (if applicable):**
- Closes: #3283
**2. Or, if no issue exists, describe the change:**
_If applicable, please follow the issue templates to provide as much detail as
possible._
**Problem:**
When using `DatabaseSessionService` with MySQL backend in google-adk v1.17.0, the application crashes with the following error: app.resources.runner:event_generator:260 - Error in event_generator: (builtins.TypeError) 'tuple' object cannot be interpreted as an integer
<img width="1237" height="129" alt="image" src="https://github.com/user-attachments/assets/0a5fc223-600a-4a92-8443-4d37fb1267f6" />
Root cause: The `DynamicPickleType` class in `database_session_service.py` configures MySQL dialect to use `LONGBLOB` for storing pickled data (line 117-118), but the `process_bind_param` and `process_result_value` methods only handle pickle serialization/deserialization for Spanner dialect, not MySQL. This causes MySQL to attempt storing raw Python objects instead of pickled bytes, leading to serialization errors and potential data corruption.
**Solution:**
Added MySQL to the pickle serialization logic in both `process_bind_param` and `process_result_value` methods, treating it the same way as Spanner dialect. This ensures that:
- Data is properly pickled to bytes before being stored in MySQL's LONGBLOB column
- Data is properly unpickled when retrieved from the database
- No breaking changes to existing functionality for other dialects (SQLite, PostgreSQL)
### Testing Plan
_Please describe the tests that you ran to verify your changes. This is required
for all PRs that are not small documentation or typo fixes._
**Unit Tests:**
- [x] I have added or updated unit tests for my change.
- [x] All unit tests pass locally.
**Summary of `pytest` results:**
<img width="929" height="306" alt="image" src="https://github.com/user-attachments/assets/3d548b96-ac49-4101-8405-a289a722293c" />
**Manual End-to-End (E2E) Tests:**
_Please provide instructions on how to manually test your changes, including any
necessary setup or configuration. Please provide logs or screenshots to help
reviewers better understand the fix._
### Checklist
- [x] I have read the [CONTRIBUTING.md](https://github.com/google/adk-python/blob/main/CONTRIBUTING.md) document.
- [x] I have performed a self-review of my own code.
- [x] I have commented my code, particularly in hard-to-understand areas.
- [x] I have added tests that prove my fix is effective or that my feature works.
- [x] New and existing unit tests pass locally with my changes.
- [x] I have manually tested my changes end-to-end.
- [x] Any dependent changes have been merged and published in downstream modules.
### Additional context
_Add any other context or screenshots about the feature request here._
COPYBARA_INTEGRATE_REVIEW=https://github.com/google/adk-python/pull/3282 from hung12ct:fix/mysql-pickle-serialization d9df37adb7dfbbfd8502a0fe65c4f8bca3d0d978
PiperOrigin-RevId: 825834360
