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Create Your own custom scalar

Although QtGQL provides some frequently used scalars, you might have your own complex scalars.

Tutorial - Country scalar

In order to deserialize a scalar for it to be compatible with Qt we created BaseCustomScalar. For example if you have a scalar of country code, you want to show the user a readable value.

Here is a simple implementation

from __future__ import annotations
from qtgqlcodegen.py.runtime.custom_scalars import BaseCustomScalar
from typing import Optional

country_map = {
    'isr': 'israel'
}

# BaseCustomScalar[<typeof default_value>, <typeof graphql_value>]
class CountryCode(BaseCustomScalar[str, str]):
    GRAPHQL_NAME = "CountryCode"
    DEFAULT_VALUE = "israel"  # this would be the default value.

    def parse_value(self) -> str:
        return self._value  # used in operation variables.

    @classmethod
    def deserialize(cls, v: Optional[str] = None) -> CountryCode:
        if v:
            return cls(country_map[v])
        return cls()

    def to_qt(self) -> str:
        return self._value


assert CountryCode.deserialize('isr').to_qt() == 'israel' == CountryCode().to_qt()

!!! Note You would need to add this in your config

# config.py
from qtgqlcodegen.py.compiler.config import QtGqlConfig


QtGqlConfig(custom_scalars={CountryCode.GRAPHQL_NAME: CountryCode}, ...)

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