Tortoise-orm

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- Fixed ``unique_together`` for foreign keys (114)
- Fixed Field.to_db_value method to handle Enum (113 115 116)

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- Added ability to use ``unique_together`` meta Model option

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- Fixed concurrency isolation when attempting to do multiple concurrent operations on a single connection.

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- Fixed several convenience issues with foreign relations:

- FIXED: ``.all()`` actually returns the _query property as was documented.
- New models with FK don't automatically fail to resolve any data. They can now be evaluated lazily.

- Some DB's don't support OFFSET without Limit, added caps to signal workaround, which is to automatically add limit of 1000000
- Pylint plugin to know about default ``related_name`` for ForeignKey fields.
- Simplified capabilities to be static, and defined at class level.

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* Added basic DB driver Capabilities.

Test runner now has the ability to skip tests conditionally, based on the DB driver Capabilities:

.. code-block:: python3

requireCapability(dialect='sqlite')
async def test_run_sqlite_only(self):
...

* Added per-field indexes.

When setting ``index=True`` on a field, Tortoise will now generate an index for it.

.. note::
Due to MySQL limitation of not supporting conditional index creation,
if ``safe=True`` (the default) is set, it won't create the index and emit a warning about it.

We plan to work around this limitation in a future release.

- Performance fix with PyPika for small fetch queries
- Remove parameter hack now that PyPika support Parametrized queries
- Fix typos in JSONField docstring
- Added ``.explain()`` method on ``QuerySet``.
- Add ``required`` read-only property to fields

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- Added "safe" schema generation
- Correctly convert values to their db representation when using the "in" filter
- Added some common missing field types:

- ``BigIntField``
- ``TimeDeltaField``

- ``BigIntField`` can also be used as a primary key field.