[英]python3, serialize / deserialize classes with generic collections
我正在尝试定义 class 与通用集合序列化/反序列化它到/从 json
import json
from typing import NamedTuple
from typing import Sequence
class ColumnDef(NamedTuple):
name: str
class RunConfig(NamedTuple):
columns: Sequence[ColumnDef]
def read_run_config(json_config: str) -> RunConfig:
loaded_json = json.loads(json_config)
return RunConfig(**loaded_json)
并测试:
import unittest
from model.RunConfig import read_run_config
from model.RunConfig import ColumnDef
class TestReadRunConfig(unittest.TestCase):
def test_read_run_config(self):
run_config_json = """
{
"columns": [
{
"name": "id"
}
]
}
"""
run_config = read_run_config(run_config_json)
print(f"{run_config}")
self.assertTrue(len(run_config.columns) == 1)
self.assertEqual(run_config.columns[0], ColumnDef(name="id"))
if __name__ == '__main__':
unittest.main()
Output:
RunConfig(columns=[{'name': 'id'}])
失败:
AssertionError: {'name': 'id'} != ColumnDef(name='id')
为什么 json lib 将 ColumnDef 反序列化为 Dictionary,而不是 class 实例?
正确的 class 组合使其工作:
from typing import NamedTuple
from typing import List
from typing_json import loads
class RunConfig(NamedTuple):
# Sequence didn't work, have no idea why
columns: List[ColumnDef]
# typing_json.loads works correctly
def read_run_config(json_config: str) -> RunConfig:
return loads(json_config, RunConfig)
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