feedback: Data model | msgpack.nil and box.NULL

[TarantoolBot]

Product: Tarantool
Audience/target: developers
Root document:
https://www.tarantool.io/en/doc/latest/book/box/data_model/
SME: @ alyapunov

Details

<…>

Scalar / compound
MsgPack   type
Lua type
Example value

|scalar
nil
“nil”
nil|

scalar
boolean
“boolean”
true

scalar
string
“string”
'A B C'
<…>

https://www.tarantool.io/en/doc/latest/book/box/data_model/

По-моему тут ошибка. msgpack nil это box.null, а не nil. Проверьте, пожалуйста.

[Totktonada]

nil is how the msgpack type named (if we're about the 'MsgPack type' column).

However as result of decoding of the nil msgpack value we receive box.NULL in Lua:

tarantool> type(msgpack.decode('\xc0'))
---
- cdata
...

tarantool> msgpack.decode('\xc0') == nil
---
- true
...

So it would be correct to write box.NULL instead of nil in the 'Lua type' column (and change the 'Example value' column acccordingly).

I guess there may be tricky cases with nullable fields, when a tuple does not contain the field 'physically', so we'll receive nil (not box.NULL), when access it. I don't know, whether I'm fully right here and whether we should reflect it there. I think it is better to consult with @alyapunov here.

[patiencedaur]

Related issue: #927.