Improve Var type handling for better rx.Model attribute access #2010
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Allows a Var to access relationship attributes on a model from the frontend rendering code. Fix: REF-904
Fix #1814 * Remove py3.7 workarounds, use get_args and get_origin directly * Move `can_access_attribute` to types and call recursively for union types * Extend `is_valid_var_type` to allow Union where all args are valid var types
Allows access to relationship attributes on rx.Model subclasses outside of __fields__. Use null coalescing when accessing attributes to avoid frontend errors when fields are optional. (Fix REF-905) Use the new `can_access_attribute` helper to support vars with Union types. If a state var is Optional and no default is provided, use None
* only check for default default when the field is marked required * grab the first item in a Literal if no default is given
Ensure that null coalescing is applied when accessing vars that default to None
All the type: ignore comments are because the annotations in the UnionState are respected...and they're not Var typed. For the Union, it's technically a type error to access fields on a Union type without a discriminator, but we'll ignore that for the purposes of Var chaining.
masenf
commented
Oct 21, 2023
| """Test that state can be defined with Union and Optional vars.""" | ||
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| class UnionState(State): | ||
| int_float: Union[int, float] = 0 |
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I don't think other Var operations are prepared to handle bare Union types...
picklelo
reviewed
Oct 24, 2023
| @@ -77,7 +78,22 @@ def dict(self, **kwargs): | |||
| Returns: | |||
| The object as a dictionary. | |||
| """ | |||
| return {name: getattr(self, name) for name in self.__fields__} | |||
| base_fields = {name: getattr(self, name) for name in self.__fields__} | |||
| relationships = {} | |||
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Can we add some comments explaining these lines
reflex/utils/types.py
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| return is_union(cls) and type(None) in get_args(cls) | ||
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| def can_access_attribute(cls: GenericType, name: str) -> GenericType | None: |
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Rename function since it doesn't return a bool
reflex/utils/types.py
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| Returns: | ||
| The type of the attribute, if accessible, or None | ||
| """ | ||
| from ..model import Model |
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from reflex.model import Model
| for arg in get_args(cls): | ||
| type_ = can_access_attribute(arg, name) | ||
| if type_ is not None: | ||
| return type_ |
picklelo
approved these changes
Oct 25, 2023
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Support accessing relationship attributes on Models
Support accessing all possible attributes when Var is annotated as a Union (fix #1814)
Use null coalescing when the var is Optional or has a default value of None
reflex.utils.types.is_unionsupports new styleUnionTypeon py3.10