Connection.copy_records_to_table does not seem to like nullable rows

[Rapptz]

• asyncpg version: 0.11
• PostgreSQL version: 9.6
• Python version: 3.6
• Platform: Windows
• Do you use pgbouncer?: No
• Did you install asyncpg with pip?: Yes
• If you built asyncpg locally, which version of Cython did you use?: N/A
• Can the issue be reproduced under both asyncio and
  uvloop?: Yes

I have no clue if this is a limitation of the COPY protocol, if so sorry for the issue.

My problem comes from attempting to insert elements using None to denote NULL. For example, given the following table:

CREATE TABLE test (id SERIAL PRIMARY KEY, entity_id INTEGER);

Attempts to create a connection and insert NULL entity_id entries results in a TypeError:

async with pool.acquire() as con:
  await con.copy_records_to_table('test', records=[(1, 1), (2, None)], 
                                          columns=('id', 'entity_id'))

Would result in:

Traceback (most recent call last):
  File "asyncpg\connection.py", line 619, in copy_records_to_table
    copy_stmt, records, intro_ps._state, timeout)
  File "asyncpg\connection.py", line 741, in _copy_in_records
    copy_stmt, None, None, records, intro_stmt, timeout)
  File "asyncpg\protocol\protocol.pyx", line 441, in copy_in (asyncpg/protocol/protocol.c:66206)
  File "asyncpg\protocol\protocol.pyx", line 389, in asyncpg.protocol.protocol.BaseProtocol.copy_in (asyncpg/protocol/protocol.c:64677)
  File "asyncpg\protocol\codecs\base.pyx", line 150, in asyncpg.protocol.protocol.Codec.encode (asyncpg/protocol/protocol.c:14433)
  File "asyncpg\protocol\codecs\base.pyx", line 95, in asyncpg.protocol.protocol.Codec.encode_scalar (asyncpg/protocol/protocol.c:13818)
  File "asyncpg\protocol\codecs\int.pyx", line 47, in asyncpg.protocol.protocol.int8_encode (asyncpg/protocol/protocol.c:29584)
TypeError: an integer is required (got type NoneType)

The documentation for the COPY protocol seems to suggest that encoding into NULL is possible:

Each tuple begins with a 16-bit integer count of the number of fields in the tuple. (Presently, all tuples in a table will have the same count, but that might not always be true.) Then, repeated for each field in the tuple, there is a 32-bit length word followed by that many bytes of field data. (The length word does not include itself, and can be zero.) As a special case, -1 indicates a NULL field value. No value bytes follow in the NULL case.

Emphasis mine, from the documentation.

However I don't know if I'm misreading it.

Thanks for your time.

[elprans]

Fixed. Thanks for catching this!

[midlewis]

I am having this issue with a value - nan of type: float are you sure it's closed out? the only way i was able to use copy records to table was to convert the entire column to a string.

[elprans]

This issue was about the handling of NULLs. NaN is a different case, please open a new issue with some example code. Thanks!