Golang Error - When marshelling data

[User123]

The data  I am trying to marshal contains serialized data. This data is received in http response.

It works perfectly when I try in version 1.4.1/ 1.4.2.

But when I try this to the latest version 1.6 it gives an error: json: unsupported type: <-chan struct {}

Why is it so? 

I am not able to upgrade to the latest version because of this.

Please help!

[Dave Cheney]

Hello,

Can you please provide a runnable code sample that shows the problem.

Thanks

Dave

[User123]

I cannot provide the full code sincethere are some dependencies.

I did fmt.println on the data that I am trying to marshall and it looks like this

%!(EXTRA main.JobResponseRoot={{92b4f95b309e8db0f8d56afadefc} http.res {[{{  map[] <nil>} "Date","Time","Time_Zone","Source","Name","Raw_Data"

 <nil> 0x10a3c2d0}]}})

[User123]

Is it giving error since it has null values? 

I'm just not able to get it. Since this code works perfectly fine in 1.4.2

[Jakob Borg]

2016-06-16 11:44 GMT+02:00 User123 <twist...@gmail.com>:
> json: unsupported type: <-chan struct {}

A channel type is not serializable, as the error says. It's possible
that older versions of Go just skipped this without generating an
error, I don't know. If that's the case you may be able to continue
getting that behavior by using a `json:"-"` field tag.

//jb

[Konstantin Khomoutov]

On Thu, 16 Jun 2016 04:55:41 -0700 (PDT)
User123 <twist...@gmail.com> wrote:

> Is it giving error since it has null values?
>
> I'm just not able to get it. Since this code works perfectly fine in
> 1.4.2

A wild guess:

1) Your error message is:

json: unsupported type: <-chan struct {}

and indeed the docs of encoding/json clearly state that certain
types cannot be sensibly marshalled and unmarshalled.
Channel types are among them.

2) Some value contained as a field of your value -- which is supposedly
of some custom struct type -- started to contain a variable of type

<-chan struct{}

somewhere between 1.4.2 and 1.6.

This might be not an immediate field of your struct-typed value
but a field of a value which is an immediate field, and so on --
deeper down the hierarchy -- because the json encoder is recursive.

Hence inspect what your value might clinge on which is not *pure data.*
Say, an http.Client instance is not pure data.

Once identified, make sure you convert your existing value you're
encoding to a value of some other type which contains nothing but pure
data values.

[...]

> > I did fmt.println on the data that I am trying to marshall and it
> > looks like this
> >

> > *%!(EXTRA main.JobResponseRoot={{92b4f95b309e8db0f8d56afadefc}
> > http.res {[{{ map[] <nil>}
> > "Date","Time","Time_Zone","Source","Name","Raw_Data"*
> > * <nil> 0x10a3c2d0}]}})*
[...]

> >>> The data I am trying to marshal contains serialized data. This
> >>> data is received in http response.
> >>>
> >>> It works perfectly when I try in version 1.4.1/ 1.4.2.
> >>>
> >>> But when I try this to the latest version 1.6 it gives an error:

> >>> *json: unsupported type: <-chan struct {}*
[...]

[User123]

Have found the cause of the issue

The message that I was trying to marshall had 0x10a3c2d0 (when fmt.Println)  which was http response.

From  https://github.com/revel/revel/issues/1037 i found that

Since Go 1.6 http.Request struct contains `Cancel <-chan struct{}` which

results in `json: unsupported type: <-chan struct {}`

So i created struct for httpRes instaed of using interface . 

type HttpRespStruct struct {

Status string

StatusCode int

Proto string

Header http.Header 

ContentLength int64

TransferEncoding []string

}

and it fixed the issue.

One thing i wanted to ask

When i return http response from a function should i use

func makeCalls() (string, error, *http.Response, error) 

or

func makeCalls() (string, error, http.Response, error)  

For the struct i created above what should be the type of header should it be *http.Header  or http.Header ??

Thank You.

[Konstantin Khomoutov]

On Fri, 17 Jun 2016 00:50:20 -0700 (PDT)
User123 <twist...@gmail.com> wrote:

[...]

> When i return http response from a function should i use

> *func makeCalls() (string, error, *http.Response, error) *
> or
> *func makeCalls() (string, error, http.Response, error) *

>
> For the struct i created above what should be the type of header

> should it be **http.Header or **http.Header ??*

Most of the code in the net/http package itself pass values of
net/http.Response by pointer, so I'd do the same.

On a side note, can I please ask you to refrain from using that lame
HTML formatting of the Google Groups interface? In a plain mail reader
which quite many people use to read mailing list your message looks
something like [1]. As you could see, guessing which asterisk denotes
a pointer and which is a stupid Google Group's attempt at emphasising
is a bit cumbersome :-)

1. http://www.fastpic.info/image/9b5a0f4dcf