Expose configuration for handling coded values like -666666666 #75
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| raise NullValueException('Unhandled coded value: ', str(v)) | ||
| else: | ||
| return func(v) | ||
| return null_wrapper |
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Another (maybe simpler) way to do this would be to avoid the decorator abstraction and use a "checking" function instead. I liked the decorator since it felt to me like a semantic way of indicating that this checking logic is a high-level modification that can be applied somewhat abstractly to the other type casting functions.
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I think I'd be a bit more comfortable with this architecture if we had more cases than just the -666666666. That said I'm comfortable to go with this approach until we accumulate more cases, and then we can potentially refactor if appropriate.
| def query(self, fields, geo, year=None, **kwargs): | ||
| cast_nulls = kwargs.get('cast_nulls', True) | ||
| if cast_nulls not in [True, False]: | ||
| raise CensusException('cast_nulls argument must be True or False') |
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I'm not totally confident in cast_nulls as the best name for the configuration argument that adjusts this behavior. In particular, it doesn't communicate that the alternative is to raise an error. Still, it was the best I had.
census/core.py Outdated
| # rest of the row values for context, so flag the | ||
| # error and continue the iteration | ||
| error = True | ||
| result = {header: item} |
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Some additional context for why we need to finish this inner loop before raising the error is that the results generated by for d in data look something like this:
{'var_name': -666666666, 'state': 42, 'county': 11}The inner loop for header, cast, item in zip(headers, types, d) processes each of these elements in turn, returning a formatted "row" for the final results. The problem with raising an error in the inner loop is that we'll only know one of these header: item pairs (like var_name: -666666666 or 'state': 42) but unless you know all of the elements it's impossible to determine which API call raised the error.
| cast them to null. | ||
| """ | ||
| # This call should return a value of -666666666 | ||
| return_val = self._client.acs5.state_county_tract('B19081_001E', |
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Do we want this to be the default behavior? I think the default should be the behavior of cast_null=True, but I'm persuadable.
| """ | ||
| Test casting -666666666 values to null. | ||
| """ | ||
| return_val = self._client.acs5.state_county_tract('B19081_001E', |
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We should also test that a warning is emitted that a value was cast to a null. Particularly if we decide to make this the default behavior.
| raise NullValueException('Unhandled coded value: ', str(v)) | ||
| else: | ||
| return func(v) | ||
| return null_wrapper |
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I think I'd be a bit more comfortable with this architecture if we had more cases than just the -666666666. That said I'm comfortable to go with this approach until we accumulate more cases, and then we can potentially refactor if appropriate.
| cast_nulls=True) | ||
| self.assertEqual(return_val[0]['B19081_001E'], None) | ||
| | ||
| def test_bad_cast_nulls_argument(self): |
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great to have these tests!
Summary
Adjust the
Client.querymethod to hande coded values, allowing the user to either:Set option 1) as the default. Implement these choices for the value
-666666666, the only one I've encountered in the wild so far.Closes #72.
Testing instructions