Question about UnmarshalJSON on non-required fields about go-jsonschema HOT 3 CLOSED

Not sure I understand what you mean. If the field is optional, we use a pointer (*string) because otherwise a missing string would be unmarshalled to an empty string. While Go developers sometimes use an empty string to mean "not present", but this is often not desirable, because that means it's not possible for your code to determine whether the original JSON had an empty string, a null string or a missing key.

Clearly string pointers are less convenient because you have to check whether they're nil, and you could accidentally write code they accessed the value without checking this first. But semantically there's no way around it. (Maybe in the future we could have a flag to control this, though.)

Just to be clear, UnmarshalJSON overrides the JSON decoder's built-in logic. We only generate it if we need to modify its behaviour or inject validation checks. If we don't, we don't generate it, and the normal JSON decoding will take place. In this case, the string field becomes either nil or a string -- it is initialized.

Did I address your concern or did you mean something else?

from go-jsonschema.

Thank you for detailed response. Yep, its all perfectly clear now. My issue was not understanding go and how pointers worked when UnmarshalJSON was called. My First foray into go was like stumbling in the dark.

from go-jsonschema.

Great!

from go-jsonschema.