net/url: Stitching complex arrays

[qingwg]

What version of Go are you using (go version)?

$ go version
go version go1.11.4 linux/amd64

Does this issue reproduce with the latest release?

yes

What operating system and processor architecture are you using (go env)?

go env Output

$ go env
GOARCH="amd64"
GOBIN=""
GOCACHE="/home/qingwuguo/.cache/go-build"
GOEXE=""
GOFLAGS=""
GOHOSTARCH="amd64"
GOHOSTOS="linux"
GOOS="linux"
GOPATH="/home/qingwuguo/go"
GOPROXY=""
GORACE=""
GOROOT="/home/linuxbrew/.linuxbrew/Cellar/go/1.11.4/libexec"
GOTMPDIR=""
GOTOOLDIR="/home/linuxbrew/.linuxbrew/Cellar/go/1.11.4/libexec/pkg/tool/linux_amd64"
GCCGO="gccgo"
CC="gcc-5"
CXX="g++-5"
CGO_ENABLED="1"
GOMOD=""
CGO_CFLAGS="-g -O2"
CGO_CPPFLAGS=""
CGO_CXXFLAGS="-g -O2"
CGO_FFLAGS="-g -O2"
CGO_LDFLAGS="-g -O2"
PKG_CONFIG="pkg-config"
GOGCCFLAGS="-fPIC -m64 -pthread -fno-caret-diagnostics -Qunused-arguments -fmessage-length=0 -fdebug-prefix-map=/tmp/go-build223599200=/tmp/go-build -gno-record-gcc-switches"

What did you do?

I want to get a query string.
If like this,I can

type B struct {
	ItemC string `json:"c"`
}

structB := B{
	ItemC: "c",
}

var params = url.Values{}
jsonbs, _ := json.Marshal(structB)
jsonmap := make(map[string]interface{})
json.Unmarshal(jsonbs, &jsonmap)
for k, v := range jsonmap {
	params.Add(k, fmt.Sprintf("%v", v))
}
fmt.Println(params.Encode())

Bug if complex arrays,like this

type A struct {
	ItemB B `json:"b"`
}

type B struct {
	ItemC string `json:"c"`
}

structB := B{
	ItemC: "c",
}
structA := A{
	ItemB: structB,
}

var params = url.Values{}
jsonbs, _ := json.Marshal(structA)
jsonmap := make(map[string]interface{})
json.Unmarshal(jsonbs, &jsonmap)
for k, v := range jsonmap {
	switch t := v.(type) {
	default:
		params.Add(k, fmt.Sprintf("%v", v))
	case map[string]interface{}:
		for kk, vv := range t {
			// this I do not know what to do
		}
	}
}
fmt.Println(params.Encode())

[agnivade]

It is not clear to me how you want the net/url package to help here.

Why can't you just do -

case map[string]interface{}:
  res, _  := json.Marshal(t)
  params.Add(k, fmt.Sprintf("%s", res))

That prints b=%7B%22c%22%3A%22c%22%7D, which gets nicely parsed back to the original value -

m, err := url.ParseQuery(`b=%7B%22c%22%3A%22c%22%7D`)
	if err != nil {
		log.Fatal(err)
	}
	fmt.Println(m) // map[b:[{"c":"c"}]]

[qingwg]

I want to

user[name]=&user[age]=test2&user[sex]=test3

like PHP example http_build_query() with complex arrays

<?php
$data = array(
    'user' => array(
        'name' => 'Bob Smith',
        'age'  => 47,
        'sex'  => 'M',
        'dob'  => '5/12/1956'
    ),
    'pastimes' => array('golf', 'opera', 'poker', 'rap'),
    'children' => array(
        'bobby' => array('age'=>12, 'sex'=>'M'),
        'sally' => array('age'=>8, 'sex'=>'F')
    ),
    'CEO'
);

echo http_build_query($data, 'flags_');
?>

this will output : (word wrapped for readability)

user[name]=Bob+Smith&user[age]=47&user[sex]=M&
user[dob]=5/12/1956&pastimes[0]=golf&pastimes[1]=opera&
pastimes[2]=poker&pastimes[3]=rap&children[bobby][age]=12&
children[bobby][sex]=M&children[sally][age]=8&
children[sally][sex]=F&flags_0=CEO

@agnivade

[agnivade]

Thanks for the clarification. It would have helped if you would have mentioned this in the first place up-front.

I think you will have to write your own logic to parse the json and build your query keys, or use some external library which can help you to easily iterate nested keys. net/url cannot help here.

If you would want something like this to be in the standard library, please open a separate proposal issue clealy mentioning why you want something like this in the standard library (also see - https://golang.org/doc/faq#x_in_std).

[qingwg]

thanks
@agnivade