I am trying to parse json using go, but I am not sure about the data structure I am building. The output is always an empty object.
data structure :
{
"Catalog": {
"Name": "TypeMime",
"Version": "1.0",
"ObjectType": {
"Area": 2,
"Service": 2,
"Version": 1,
"Number": 117
},
"Items": [
{
"ItemNamespace": "application",
"Name": "binhex-bin",
"Oid": null,
"Uid": 2201,
"DocMandatoryProperties": [],
"DocOptionalProperties": [
"Subsystem",
"Label",
"Description"
],
"DocVersionProperties": [],
"DefaultAction": null,
"Extensions": [
".bin"
],
"Confidentiality": [
"confidentiality/Public"
],
"Converter": [],
"Editor": [
"gedit"
],
"DiffEditor": [
"kompare"
],
"Icon": "",
"IdentificationPattern": [
"^\\S+.bin$"
]
},
{other items}
}
type ObjectType struct {
Area int `json:"Area"`
Service int `json:"Service"`
Version int `json:"Version"`
Number int `json:"Number"`
}
type Catalog struct {
Name string `json:"Name"`
Version string `json:"Version"`
ObjectType ObjectType `json:"ObjectType"`
Items []Item `json:"Items"`
}
type Item struct {
ItemNamespace string `json:"ItemNamespaceItems"`
Name string `json:"Name"`
Oid int `json:"Oid"`
Uid int `json:"Uid"`
DocMandatoryProperties []string `json:"DocMandatoryProperties"`
DocOptionalProperties []string `json:"DocOptionalProperties"`
DocVersionProperties []string `json:"DocVersionProperties"`
DefaultAction string `json:"DefaultAction"`
Extensions []string `json:"Extensions"`
Confidentiality []string `json:"Confidentiality"`
Converter []string `json:"Converter"`
Editor []string `json:"Editor"`
DiffEditor []string `json:"DiffEditor"`
Icon string `json:"Icon"`
IdentificationPattern []string `json:"IdentificationPattern"`
}
var catalog Catalog
// Open our jsonFile
jsonFile, err := os.Open("path.json")
// if we os.Open returns an error then handle it
if err != nil {
fmt.Println(err)
}
fmt.Println("Successfully Opened json")
// defer the closing of our jsonFile so that we can parse it later on
defer jsonFile.Close()
byteValue, err := ioutil.ReadAll(jsonFile)
if err != nil {
fmt.Println("error input file :",err)
}
err = json.Unmarshal(byteValue, &catalog)
if err != nil {
fmt.Println("error input file :",err)
}
fmt.Println("catalog from json : ",catalog)
I am getting this output : { {0 0 0 0} []}
So I am thinking, maybe the structures that I have built are not correct or Go cannot handle "null" values. The JSON file is correctly opened and converted to bytes, I am not getting any errors, just not what I was expecting i.e. the json parse in my Catalog variable.
Any suggestions ?
err = json.Unmarshal(byteValue, &catalog)
You tell go that you're about to parse a Catalog, but then do something else. What you actually do is give it an (unnamed) object that has a "Catalog" key with corresponding value. Go can't find any of catalog keys in this object and that's why you get all empty fields.
Related
I'm trying to unmarshal some nested JSON which looks like:
{
"id": "aRandomId",
"type": "aRandomType",
"aRandomField": {
"type": "someType",
"createdAt": "2020-07-07T15:50:02",
"object": "anObject",
"modifiedAt": "2020-07-07T15:50:02"
},
"aParameter": {
"type": "Property",
"createdAt": "2020-07-07T15:50:02",
"value": "myValue",
"modifiedAt": "2020-07-07T15:50:02"
},
"location": {
"type": "GeoProperty",
"value": {
"type": "Point",
"coordinates": [
7.0054,
40.9999
]
}
},
... other things with type, value ...
"createdAt": "2020-07-07T15:50:02",
"modifiedAt": "2020-07-07T15:50:02",
}
I would like to get all keys and values which are: type, createdAt, Value (also if they are nested)
Actually, I have 2 structs:
type Attribute struct {
Type string `json:"type"`
CreatedAt string `json:"createdAt"`
Value string `json:"value"`
ModifiedAt string `json:"modifiedAt"`
}
type Entity struct {
Id string `json:"id"`
Type string `json:"type"`
CreatedAt string `json:"createdAt"`
Attribute Attribute
}
in := []byte(buf.String())
var entity Entity
err := json.Unmarshal(in, &entity)
if err != nil {
panic(err)
}
frame.Fields = append(frame.Fields,
data.NewField("key", nil, []string{"type : ", "createdAt : ", "name : "}),
)
frame.Fields = append(frame.Fields,
data.NewField("value", nil, []string{entity.Type, entity.CreatedAt, entity.Attribute.Value}),
)
The problem is there can be several different Attribute struct andIi can't provide them all.
I would like to display all key (only type, createdAt and Value) in one frame and all their value in another.
Maybe have something like that?
type Entity struct {
attribute List<Attribute>
}
type Attribute struct{
Type string
CreatedAt string
Value string
ModifiedAt string
}
The problem is there can be several different Attribute struct andIi can't provide them all
It looks like your JSON data can have a set of keys with similar values (Attribute) and you can't know how many of them might be in the data.
For this case, you can use a map[string]json.RawMessage as the starting entity to unmarshal to
var e map[string]json.RawMessage
if err := json.Unmarshal([]byte(jsonData), &e); err != nil {
panic(err)
}
You can then range over the values to see if you can unmarshal them into Attribute type
for k, v := range e {
var a Attribute
if err := json.Unmarshal(v, &a); err == nil {
log.Printf("Got attribute %s: %s", k, string(v))
}
}
Run it on playground
I have a json stream as follows ...
[
{
"page": 1,
"pages": 7,
"per_page": "2000",
"total": 13200
},
[
{
"indicator": {
"id": "SP.POP.TOTL",
"value": "Population, total"
},
"country": {
"id": "1A",
"value": "Arab World"
},
"value": null,
"decimal": "0",
"date": "2019"
},
{
"indicator": {
"id": "SP.POP.TOTL",
"value": "Population, total"
},
"country": {
"id": "1A",
"value": "Arab World"
},
"value": "419790588",
"decimal": "0",
"date": "2018"
},
...
]
]
And I'm trying to decode it ... so I have the following struct ... but I keep getting
"cannot unmarshal array into Go value of type struct { P struct ... "
type Message []struct {
P struct {
Page int
}
V []struct {
Indicator struct {
Id string
Value string
}
Country struct {
Value string
}
Value string
Decimal string
Date string
}
}
My struct looks to match the json ... but obviously not! Any ideas?
Since your JSON array have two different types first unmarshal them into a slice of json.RawMessage which is []byte as underlying type so that we can unmarshal again JSON array data.
So unmarshal data for P and V struct type using index directly (predict) or detect if object(starting with '{') then unmarshal into P and array(starting with '[') then unmarshal into V. Now prepare your Message using those data.
type Message struct {
PageData P
ValData []V
}
type P struct {
Page int
}
type V struct {
Indicator struct {
Id string
Value string
}
Country struct {
Value string
}
Value string
Decimal string
Date string
}
func main() {
var rawdata []json.RawMessage
json.Unmarshal([]byte(jsonData), &rawdata)
var pageData P
json.Unmarshal(rawdata[0], &pageData)
var valData []V
json.Unmarshal(rawdata[1], &valData)
res := Message{pageData, valData}
fmt.Println(res)
}
var jsonData = `[...]` //your json data
Full code in Go Playground
As poWar said, the JSON you actually have is a list of objects whose types do not conform to each other. You must therefore unmarshal into something capable of holding different object types, such as interface{} or—since there is an outer array—[]interface{}.
You can also, if you like, decode into a []json.RawMessage. The underlying json.RawMessage itself has underlying type []byte so that it's basically the undecoded "inner" JSON. In at least some cases this is going to be more work than just decoding directly to []interface{} and checking each resulting interface, but you can, if you wish, decode to struct once you have the JSON separated out. For instance:
func main() {
var x []json.RawMessage
err := json.Unmarshal(input, &x)
if err != nil {
fmt.Printf("err = %v\n", err)
return
}
if len(x) != 2 {
fmt.Println("unexpected input")
return
}
var page struct {
Page int
}
err = json.Unmarshal(x[0], &page)
if err != nil {
fmt.Printf("unable to unmarshal page part: %v\n", err)
return
}
fmt.Printf("page = %d\n", page.Page)
// ...
}
Here on the Go Playground is a more complete example. See also Eklavya's answer.
Looking at your struct, your corresponding JSON should look something like this.
[
{
"P": {"page": 1},
"V": [
{
"Indicator": {"Id": ...},
"Country": {"Value":""},
"Value": "",
...
}
]
},
...
]
The JSON structure you are trying to Unmarshal looks like a list of objects where each object is not of the same type. You can start unmarshalling them into interfaces and defining each interface based on the object being unmarhsalled.
package main
import (
"encoding/json"
"log"
)
type Message []interface{}
func main() {
data := `[{"page":1,"pages":7,"per_page":"2000","total":13200},[{"indicator":{"id":"SP.POP.TOTL","value":"Population, total"},"country":{"id":"1A","value":"Arab World"},"value":null,"decimal":"0","date":"2019"},{"indicator":{"id":"SP.POP.TOTL","value":"Population, total"},"country":{"id":"1A","value":"Arab World"},"value":"419790588","decimal":"0","date":"2018"}]]`
var m Message
if err := json.Unmarshal([]byte(data), &m); err != nil {
log.Fatalf("could not unmarshal")
}
log.Printf("message: %v", m)
}
Output:
message: [map[page:1 pages:7 per_page:2000 total:13200] [map[country:map[id:1A value:Arab World] date:2019 decimal:0 indicator:map[id:SP.POP.TOTL value:Population, total] value:<nil>] map[country:map[id:1A value:Arab World] date:2018 decimal:0 indicator:map[id:SP.POP.TOTL value:Population, total] value:419790588]]]
[Edit]: Ideally you should change your JSON to be structured better for unmarshalling. If you do not have control on it, then your corresponding Go structure is just embedded maps of string to interfaces, which you will have to manually type cast and access.
I am trying to create a JSON object on the fly based on the data received from the API.
Sample Data received: Unmarshalled the data into CiItems struct given below
{
"class_name": "test",
"configuration_items": [
{
"id": "ea09a24f-01ef-42ad-ab19-e0369341d9b3",
"ci_name": "makk",
"comments": null,
"created_by": "mike",
"updated_by": "sam",
"created": "2019-08-02T21:16:35.656Z",
"updated": "2019-08-02T21:21:08.073Z",
"ci_state_id": "randomid",
"super_ci_id": null,
"ci_attributes": [
{
"attribute_id": "c995c693-b97c-4863-a61b-81a5d904c967",
"df_attribute_value": "xsmall",
"attribute_name": "tname",
"data_type": "string"
},
{
"attribute_id": "58845f48-7d2a-4c8c-8591-eaf59a23d84d",
"df_attribute_value": "vmware",
"attribute_name": "provider",
"data_type": "string"
}
]}]}
Below are the structs created:
type Attribute struct {
AttributeID string `json:"attribute_id "`
DfAttributeValue string `json:"df_attribute_value"`
AttName string `json:"attribute_name"`
DataType string `json:"data_type"`
}
// Attributes - array of Attribute
type Attributes []Attribute
// CiItem - confiuraion item of a VM
type CiItem struct {
ID string `json:"ci_id"`
Created string `json:"created"`
Updated string `json:"updated"`
CreatedBY string `json:"created_by"`
UpdatedBY string `json:"updated_by"`
Atts Attributes `json:"ci_attributes"`
}
// CiItems - array of CiItem
type CiItems struct {
ClassName string `json:"class_name"`
Items []CiItem `json:"configuration_items"`
}
Code to unmarshal the data and create a extracted Json:
func (client *Client) GetList() (CiItems, error) {
var out CiItems
err := client.doJsonRequest("GET", &out)
log.Info(out)
if err != nil {
return out, err
}
var output map[string]interface{}
//parseMap(out.Items[0].(map[string]interface{}))
extractBase(out.Items[0], &output)
return out, nil
}
func extractBase(ci interface{}, output interface{}) {
fields := reflect.TypeOf(ci)
values := reflect.ValueOf(ci)
num := fields.NumField()
for i := 0; i < num; i++ {
field := fields.Field(i)
value := values.Field(i)
if string(field.Name) != "Atts" {
name := string(field.Name)
output[name] = string(value)
}
}
}
I am trying to create a JSON with key value of id, ci_name, created_by, updated_by, attribute_name as below
{
"ci_name": "makk",
"created_by": "mike",
"updated_by": "sam",
"created": "2019-08-02T21:16:35.656Z",
"updated": "2019-08-02T21:21:08.073Z",
"tname": "xsmall",
"provider": "vmware"
}
I have tried using reflect and other methods
Create a map using values from CiItem fields and return it from the function.
func extractBase(ci *CiItem) map[string]interface{} {
result := map[string]interface{}{
"ci_name": ci.Name,
"created_by": ci.CreatedBY,
"updated_by": ci.UpdatedBY,
"created": ci.Created,
"updated": ci.Updated,
}
for _, a := range ci.Atts {
result[a.AttName] = a.DfAttributeValue
}
return result
}
So I am trying to fetch the analytics of an app by pinging and endpoint. I make the GET request which is successfull (no errors there) but I am unable to decode the JSON
I need to to decode the following json into structs
{
"noResultSearches": {
"results": [
{
"count": 1,
"key": "\"note 9\""
},
{
"count": 1,
"key": "nokia"
}
]
},
"popularSearches": {
"results": [
{
"count": 4,
"key": "6"
},
{
"count": 2,
"key": "\"note 9\""
},
{
"count": 1,
"key": "nokia"
}
]
},
"searchVolume": {
"results": [
{
"count": 7,
"key": 1537401600000,
"key_as_string": "2018/09/20 00:00:00"
}
]
}
}
For which I am using the following structs
type analyticsResults struct {
Count int `json:"count"`
Key string `json:"key"`
}
type analyticsVolumeResults struct {
Count int `json:"count"`
Key int64 `json:"key"`
DateAsStr string `json:"key_as_string"`
}
type analyticsPopularSearches struct {
Results []analyticsResults `json:"results"`
}
type analyticsNoResultSearches struct {
Results []analyticsResults `json:"results"`
}
type analyticsSearchVolume struct {
Results []analyticsVolumeResults `json:"results"`
}
type overviewAnalyticsBody struct {
NoResultSearches analyticsNoResultSearches `json:"noResultSearches"`
PopularSearches analyticsPopularSearches `json:"popularSearches"`
SearchVolume analyticsSearchVolume `json:"searchVolume"`
}
I make a GET request to an endpoint and then use the response body to decode the json but I get an error. Following is a part of the code that stays in my ShowAnalytics function
func ShowAppAnalytics(app string) error {
spinner.StartText("Fetching app analytics")
defer spinner.Stop()
fmt.Println()
req, err := http.NewRequest("GET", "<some-endpoint>", nil)
if err != nil {
return err
}
resp, err := session.SendRequest(req)
if err != nil {
return err
}
spinner.Stop()
var res overviewAnalyticsBody
dec := json.NewDecoder(resp.Body)
err = dec.Decode(&res)
if err != nil {
return err
}
fmt.Println(res)
return nil
}
json: cannot unmarshal array into Go struct field
overviewAnalyticsBody.noResultSearches of type
app.analyticsNoResultSearches
What am I doing wrong here? Why do I get this error?
EDIT: After you edited, your current code works as-is. Check it out here: Go Playground.
Original answer follows.
There is some inconsistency between the code you posted and the error you get.
I tried it on the Go Playground (here's your version), and I get the following error:
json: cannot unmarshal number into Go struct field analyticsVolumeResults.key of type string
We get this error because in the JSON searchVolume.results.key is a number:
"key": 1537401600000,
And you used string in the Go model:
Key string `json:"key"`
If we change it to int64:
Key int64 `json:"key"`
It works, and prints (try it on the Go Playground):
{{[{1 "note 9"} {1 nokia}]} {[{4 6} {2 "note 9"} {1 nokia}]} {[{7 1537401600000 2018/09/20 00:00:00}]}}
If that key may sometimes be a number and sometimes a string, you may also use json.Number in the Go model:
Key json.Number `json:"key"`
I'm using Go for a simple http client. Here's the entity I'm unmarshalling:
type Message struct {
Id int64
Timestamp int64
Text string
Author User
LastEdited int64
}
type User struct {
Id int64
Name string
}
A single entity looks like this in JSON:
{
"text": "hello, can you hear me?",
"timestamp": 1512964818565,
"author": {
"name": "andrea",
"id": 3
},
"lastEdited": null,
"id": 8
}
Go/json has no problem unmarshalling the single entity:
var m Message
err = json.Unmarshal(body, &m)
if err != nil {
printerr(err.Error())
}
println(m.Text)
However, if the return of the endpoint is multiple entities:
[
{
"text": "hello, can you hear me?",
"timestamp": 1512964800981,
"author": {
"name": "eleven",
"id": 4
},
"lastEdited": null,
"id": 7
}
]
And I change my corresponding Unmarshall to work on a slice of structs, Go throws an error:
var m []Message
err = json.Unmarshal(body, &m)
if err != nil {
printerr(err.Error()) // unexpected end of JSON input
}
for i := 0; i < len(m); i++ {
println(m[i].Text)
}
What gives?
Works fine for me (try it on playground), where are you getting the payload data from? sounds like that's truncating it.
package main
import (
"encoding/json"
"fmt"
)
type Message struct {
Id int64
Timestamp int64
Text string
Author User
LastEdited int64
}
type User struct {
Id int64
Name string
}
func main() {
body := []byte(`[
{
"text": "hello, can you hear me?",
"timestamp": 1512964800981,
"author": {
"name": "eleven",
"id": 4
},
"lastEdited": null,
"id": 7
}
]`)
var m []Message
err := json.Unmarshal(body, &m)
if err != nil {
fmt.Printf("error: %v") // unexpected end of JSON input
}
for i := 0; i < len(m); i++ {
fmt.Println(m[i].Text)
}
}
running it gives this output
hello, can you hear me?