Services: - Orders: - ID: $save ID1SupplierOrderCode: $SupplierOrderCode- ID: $save ID2SupplierOrderCode: 111111I want to convert this yaml string to json, cause the source data is dynamic, so I can't map it to a struct:
var body interface{}err := yaml.Unmarshal([]byte(s), &body)Then I want to convert that interface to json string again:
b, _ := json.Marshal(body)But an error occur:
panic: json: unsupported type: map[interface {}]interface {}Best Answer
Foreword: I optimized and improved the below solution, and released it as a library here: github.com/icza/dyno. The below convert() function is available as dyno.ConvertMapI2MapS().
The problem is that if you use the most generic interface{} type to unmarshal into, the default type used by the github.com/go-yaml/yaml package to unmarshal key-value pairs will be map[interface{}]interface{}.
First idea would be to use map[string]interface{}:
var body map[string]interface{}But this attempt falls short if the depth of the yaml config is more than one, as this body map will contain additional maps whose type will again be map[interface{}]interface{}.
The problem is that the depth is unknown, and there may be other values than maps, so using map[string]map[string]interface{} is not good.
A viable approach is to let yaml unmarshal into a value of type interface{}, and go through the result recursively, and convert each encountered map[interface{}]interface{} to a map[string]interface{} value. Both maps and slices have to be handled.
Here's an example of this converter function:
func convert(i interface{}) interface{} {switch x := i.(type) {case map[interface{}]interface{}:m2 := map[string]interface{}{}for k, v := range x {m2[k.(string)] = convert(v)}return m2case []interface{}:for i, v := range x {x[i] = convert(v)}}return i}And using it:
func main() {fmt.Printf("Input: %s\n", s)var body interface{}if err := yaml.Unmarshal([]byte(s), &body); err != nil {panic(err)}body = convert(body)if b, err := json.Marshal(body); err != nil {panic(err)} else {fmt.Printf("Output: %s\n", b)}}const s = `Services:- Orders:- ID: $save ID1SupplierOrderCode: $SupplierOrderCode- ID: $save ID2SupplierOrderCode: 111111`Output:
Input: Services:- Orders:- ID: $save ID1SupplierOrderCode: $SupplierOrderCode- ID: $save ID2SupplierOrderCode: 111111Output: {"Services":[{"Orders":[{"ID":"$save ID1","SupplierOrderCode":"$SupplierOrderCode"},{"ID":"$save ID2","SupplierOrderCode":111111}]}]}One thing to note: by switching from yaml to JSON via Go maps you'll lose the order of the items, as elements (key-value pairs) in a Go map are not ordered. This may or may not be a problem.
http://sigs.k8s.io/yaml is "a wrapper around go-yaml designed to enable a better way of handling YAML when marshaling to and from structs". Among other things, it provides yaml.YAMLToJSON method that should do what you want.
I was having the same issue and the icza's answer helped me.Additionally I improved the convert() function a little bit, so it visits existing map[string]interface{} nodes to search for inherited map[interface{}]interface{} nodes deep inside.
func convert(i interface{}) interface{} {switch x := i.(type) {case map[interface{}]interface{}:m2 := map[string]interface{}{}for k, v := range x {m2[k.(string)] = convert(v)}return m2case map[string]interface{}:m2 := map[string]interface{}{}for k, v := range x {m2[k] = convert(v)}return m2case []interface{}:for i, v := range x {x[i] = convert(v)}}return i}