Support nested dictionary key completion

[javad94]

Environment data

• Language Server version: 2021.6.3
• OS and version: Windows 10 20H2
• Python version (& distribution if applicable, e.g. Anaconda): Python 3.7.5 using Anaconda

Expected behaviour

Pylance should show key completion for integer and nested keys.

Actual behaviour

Pylance does not show key completion for integer and nested keys.

Logs

XXX

Code Snippet / Additional information

somedict = {
    'test': 1,
    'test2':2,
    '3test':3,
    '4':4,
    5: 5,
    '_test6': 6,
    'testnested': {'n1':1, 2:2}
}

Pylance does not show key completion for integer keys (in this case 5)

Pylance does not show key completion for nested keys

[judej]

Need to investigate why 5 does not show up

[heejaechang]

first one is a bug, but nested key is new feature request. so, probably we will fix the first one first,

[erictraut]

Our completion provider has logic for string literals but not for other literals like integers, floats, complex, etc.

somedict = {
    5: 0,
    3.41: 0,
    3j: 0,
    [3, 4]: 0,
}

We'll need to decide where to draw the line. The vast majority of keys within dicts are strings. It drops off very quickly after that. Integers are probably next.

[javad94]

@erictraut I agree with you.

[cdce8p]

Aside from strings, I usually see constants that reference strings. These seem to be unsupported at the moment, unfortunately.

KEY_1 = "Some key"
KEY_2 = "Some other key"

somedict = {
    KEY_1: 1,
    KEY_2: 2,
    "key_3": 3,
}

somedict[]

[yvvt0379]

@erictraut I have to explain that in your example, the last key [3, 4] is invalid because it's mutable. See the reasons https://docs.python.org/3/faq/design.html#why-must-dictionary-keys-be-immutable

[erictraut]

Yes, good point. Replace the list with a tuple.

[judej]

Moving this issue to discussion as an enhancement request for comments and upvotes.