Do Not Attempt Decoding When We Know It Will Fail #230
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This commit changes the `orDefault` and `orDefaultAccumulating` methods to not attempt decoding when we,
* Know we have a default value
* We know decoding will fail.
The code is made a bit more complex and less optimal because we have to run the decoder when the value is `null`, though we don't when it is missing. This is because the Circe `Decoder[Option[A]]` has a special case for this input `{"a": null}`. All other types would consider the value `null` and the missing key `"a"` to be the same case and use a default, but `Decoder[Option[A]]` considers `{"a": null}` as `Right(None)`.
See the test `"Option[T] with default should be None if null decoded"` for a complete example.
In the future, for defaulting codecs, we might consider treating a missing value and `JNull` the same in all cases, even for `Option`.
This commit also adds a benchmark package which was used to verify the issue referenced in circe/circe#1972.
Note, this optimization works _around_ the issue in circe/circe#1972, but there is still an issue in circe proper for circe/circe#1972. This optimization is good with or without the issue described in circe/circe#1972.
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@zarthross any thoughts here? FWIW, I can make this better if I can match on the |
zarthross
approved these changes
Oct 21, 2022
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This commit changes the
orDefaultandorDefaultAccumulatingmethods to not attempt decoding when we,The code is made a bit more complex and less optimal because we have to run the decoder when the value is
null, though we don't when it is missing. This is because the CirceDecoder[Option[A]]has a special case for this input{"a": null}. All other types would consider the valuenulland the missing key"a"to be the same case and use a default, butDecoder[Option[A]]considers{"a": null}asRight(None).See the test
"Option[T] with default should be None if null decoded"for a complete example.In the future, for defaulting codecs, we might consider treating a missing value and
JNullthe same in all cases, even forOption.This commit also adds a benchmark package which was used to verify the issue referenced in circe/circe#1972.
Note, this optimization works around the issue in circe/circe#1972, but there is still an issue in circe proper for circe/circe#1972. This optimization is good with or without the issue described in circe/circe#1972.