Volodymyr Magamedov

Implement connection checks using PING frame

2

This will help identify when connection becomes broken. See also: https://github.com/grpc/grpc/blob/master/doc/PROTOCOL-HTTP2.md#ping-frame

StreamIDTooLowError when trying to send headers into closed stream

1

Hi! I'm getting errors like this on the server-side: ```pytb Traceback (most recent call last): File "/usr/local/lib/python3.6/dist-packages/grpclib/server.py", line 310, in request_handler await method.func(stream) File "/usr/local/lib/python3.6/dist-packages/featureflags/server/rpc/service.py", line 51, in Exchange await...

When we have a function definition which accepts `Mapping[String, Any]`, and we pass an option's value with the same type, currently we get this error: ```pytb Traceback (most recent call...

... and ability to use `select` expressions with joins as a source of data.

```python Link('entities', ..., require=['id', 'user_id']) ```

It is possible to use several columns as one value by using `sqlalchemy.sql.expression.tuple_` expression. `from_column` and `to_column` should also support several columns/arbitrary expressions.

For example: ```python Field('someField', String, some_sg.c(S.this.some_field)) ``` Infer which type `S.this.some_field` returns and check that it matches `String` type.