encoding/xml: omit parent tags if value is empty #2

[kdar]

What steps will reproduce the problem?
http://play.golang.org/p/m2rU4cPOBo

What is the expected output?
<OmitEmpty></OmitEmpty>

What do you see instead?
<OmitEmpty><Vars></Vars></OmitEmpty>

Please provide any additional information below.
https://golang.org/cl/6569067/

This was originally: https://golang.org/issue/4168
Ran into this issue today making a restful API service. Ended up having to make my own
custom Marshaller.

[LeGEC]

Comment 1:

Further comments on this issue:
In this case, the "omitempty" directive has actually no effect :
http://play.golang.org/p/HG7io7mH7l
IMHO, the extra ",omitempty" should be taken as a clear directive in this case (1-step
deep node list).
For a deeper nested list, the "expected behavior" is ambiguous :
type Ambiguous struct {
    Bees []string `xml:"Beez>Bees>Bee,omitempty"` //I don't have a "natural" argument for this one ...
}
My choice would be : ommit the base "Beez" node in the output.
One point for this choice :
- if we ommit the base node, there still is a way to write a type structure which will
use only xml annotations and which will contain "<Beez></Beez>" in the
Marshal-ed output :
type Disambiguated struct {
    Beez Nested `xml:"Beez"`
}
type Nested struct {
    Bees []string `xml:"Bees>Bee,omitempty"`
}
- if we don't ommit the base node, I don't see how to achieve this without writing a
custom Marshaller.
Regarding the "break backward compatibility" part :
 * it shouldn't break the Unmarshaling of a previously Marshal-ed structure,
 * it could indeed change the output of a program, but as I stated, I think this output is the one expected by the programmer if ",omitempty" is specified.
This is an adapted repost of this comment :
https://golang.org/issue/4168?c=10

[rsc]

Comment 2:

Are you asking for an omitparent tag? Because we're still not going to change the
behavior of omitempty at this point.

[rsc]

Comment 3:

Status changed to WaitingForReply.

[rsc]

Comment 4:

Labels changed: added release-none.

[kdar]

Comment 5:

Well, I guess that would be the only option given the Go1 compat guarantee.

[LeGEC]

Comment 6:

@rsc : I'd rather have the modified behavior in 1.3.1 or 1.4 than add an extra directive
just for this corner case.

[gopherbot]

Comment 7 by TheDonDaniello:

I have the same problem: no way to get rid of the parent tag even if it's marked with
omitempty and does not have any children or attributes.

[griesemer]

Comment 8:

Labels changed: added repo-main.

[sshikaree]

You can use a pointer to a structure. While it's uninitialized, pointer is nil and omited by marshaller.
http://play.golang.org/p/tdiGkAdQAQ
But I think it would be more convenient if we could also omit the structure ("Time" in example).