encoding/json: Unexpected marshal behavior #21903
Comments
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Note that we don't use the issue tracker to ask questions. Please see https://golang.org/wiki/Questions . |
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In my opinion, it's a bug since it works for some cases. |
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I should note that Go 1.0 had the user's expected behavior: {"value":"A"}
{"value":"B"}
{"value":"C"}The current output has been the case since Go1.1. |
dsnet
added
the
NeedsInvestigation
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Maybe Go 1.0 is buggy. I feel the results of the later versions are right. func (this *B) MarshalJSON() ([]byte, error) {
type Copy B
c := (*Copy)(this)
return json.Marshal(c)
}The type The |
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Doesn't seem to be anything to do here. |
I created a custom MarshalJSON for my struct and it outputs the wrong struct if I have customs MarshalJSON nested in my struct.
I'm trying to understand why it doesn't work as expected. I know that there are some limitations with type redefinition but it works well if I don't nest any struct with a custom MarshalJSON.
What version of Go are you using (
go version)?1.8
Does this issue reproduce with the latest release?
Yes
What operating system and processor architecture are you using (
go env)?Linux
What did you do?
https://play.golang.org/p/Mp1ot20ILA
This example is just to be able to reproduce the problem. I know it doesn't make any sense the custom Copy type, but in a real problem, I would extend Copy type by adding custom fields.
What did you expect to see?
{"value":"A"}
{"value":"B","A":{"value":"A"}}
{"value":"C","A":{"value":"A"},"B":{"value":"B","A":{"value":"A"}}}
or at least
{"value":"A"}
{"value":"B"}
{"value":"C"}
What did you see instead?
{"value":"A"}
{"value":"A"}
{"value":"C","A":{"value":"A"},"B":{"value":"A"}}
The first line is ok.
The second line is completely wrong.
The third line is almost ok.
C has two nested objects with a custom marshal and it works almost good.
B has just one and it prints the output of A.
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