[REF-3328] Implement __getitem__ for ArrayVar

[adhami3310]

No description provided.

[linear]

REF-3328 Implement __getitem__ for ArrayVar

[masenf]

i still need to do more testing, but it doesn't look like the _var_type is properly passed for the keys, values and entries operations

[masenf]

partway through the new stuff

[masenf]

the following code needs to work if the annotation is there

>>> ov2 = rx._x.vars.LiteralVar.create({"foo": "bar"})
>>> ov2["foo"].upper()
Traceback (most recent call last):
  File "<stdin>", line 1, in <module>
  File "/Users/masen/code/reflex-dev/reflex/reflex/vars.py", line 1726, in upper
    return self._replace(
           ^^^^^^^^^^^^^^
  File "/Users/masen/code/reflex-dev/reflex/reflex/experimental/vars/base.py", line 160, in _replace
    return type(self)(**field_values)
           ^^^^^^^^^^^^^^^^^^^^^^^^^^
TypeError: ObjectItemOperation.__init__() got an unexpected keyword argument '_var_name'

This seems to be hitting upper in the base Var, because the resulting ObjectItemOperation isn't a StringVar.

Similar but different, if we cast the value to dict[str, str], then it still doesn't really work

>>> ov = rx._x.vars.LiteralVar.create({"foo": "bar"}).to(rx._x.vars.ObjectVar, dict[str,str])
Warning: `rx._x` contains experimental features and might be removed at any time in the future .
>>> ov["foo"].lower()
Traceback (most recent call last):
  File "<stdin>", line 1, in <module>
  File "/Users/masen/code/reflex-dev/reflex/reflex/vars.py", line 1702, in lower
    raise VarTypeError(
reflex.utils.exceptions.VarTypeError: Cannot convert non-string var ({ ["foo"] : "bar" })["foo"] to lowercase.
>>> ov["foo"]
ObjectItemOperation(_var_name='({ ["foo"] : "bar" })["foo"]', _var_type=<class 'reflex.experimental.vars.base.ImmutableVar'>, _var_data=None, value=ToObjectOperation(_var_name='({ ["foo"] : "bar" })', _var_type=dict[str, str], _var_data=None, _original_var=LiteralObjectVar(_var_name='({ ["foo"] : "bar" })', _var_type=typing.Dict[str, str], _var_data=None, _var_value={'foo': 'bar'})), key=LiteralStringVar(_var_name='"foo"', _var_type=<class 'str'>, _var_data=None, _var_value='foo'))

in this case, the resulting ObjectItemOperation gets _var_type=ImmutableVar which doesn't seem quite right.

It seems like these item accessing operations probably need to also use .to in order to correctly cast the resulting value based on the annotation in the original var.

we also need test cases for these chain operations

[masenf]

i think rx.utils.types._issubclass implements this already

[masenf]

what is the json() method intended to be used for?