i have var (name result["error_type"]) with type
[]interface {}
and value
[map[reason:map[phone:empty] send_at:1.636697291e+09 status:error]]
how i cat get value from type []interface {}
example result["error_type"]["128"]["reason"]["phone"]
this type i got from
var result map[string]interface{}
json.NewDecoder(r.Body).Decode(&result)
r.Body has Json
{
"offer_name":"EbcBankruptcy",
"offer_id":"288",
"partner_name":"середов",
"partner_id":"1",
"type_system":"gb",
"status":"success",
"date_request":"2021-01-02 11:03",
"bank_name":"alfa",
"bank_id":"1",
"type_product":"1",
"error_type":{"128": [{"reason": {"phone": "Отсутствует обязательное поле номер телефона"}, "status": "error", "send_at": 1636697291}], "200": [{"reason": {"phone": "Отсутствует обязательное поле номер телефона"}, "status": "error", "send_at": 1636697281}]},
"request_id":"1"
}
also i dont create structure error_type for json.NewDecoder parse because i dont know what kind id will be in error_type in json (128, 200, 300)
i try get value
test["reason"]["phone"]
but, its not work
also cast to
map[string]interface{}
its not work
As far as the understanding from the question, what I understand is you can format the data as following.
type Payload struct {
OfferName string `json:"offer_name"`
OfferID string `json:"offer_id"`
PartnerName string `json:"partner_name"`
PartnerID string `json:"partner_id"`
TypeSystem string `json:"type_system"`
Status string `json:"status"`
DateRequest string `json:"date_request"`
BankName string `json:"bank_name"`
BankID string `json:"bank_id"`
TypeProduct string `json:"type_product"`
// you can use the type map of array of error data here
ErrorType map[string][]ErrorData `json:"error_type"`
RequestID string `json:"request_id"`
}
type ErrorData struct {
Reason Reason `json:"reason"`
Status string `json:"status"`
SendAt int `json:"send_at"`
}
type Reason struct {
Phone string `json:"phone"`
}
With the following you can unmarshal the data to
fmt.Printf("%+v", p.ErrorType["128"][0].Reason)
In the case you are unable to know the keys of the map, you can still range over the map values and get the data.
Here is the playground link https://go.dev/play/p/oTF0JUwOj0D
I want to omit certain structs nested in a JSON request. I've created a rest API on golang which reads a message body from an http request, decodes it into the struct defined in the code and inserts it into Mongo DB
My structs are as follows. Note that for the nested structure C, I use a pointer in order to be able to omit it.
type A struct {
Title string `json:"title"`
Text string `json:"text"`
Data B `json:"data"`
}
type B struct {
Product *C `json:"product,omitempty"`
ExternalLink string `json:"external_link,omitempty"`
}
type C struct {
Name string `json:"name"`
Id int `json:"id"`
}
Here is how I decode it (Didn't go for Json.Unmarshall as I read that for http bodies, decoding should be used over unmarshall)
func NewMessage(req *http.Request) *A {
var newMessage *A
json.NewDecoder(req.Body).Decode(&newMessage)
messageInData := newMessage
return newMessage
}
The "newMessage" upon return is inserted into Mongo directly. However, Even if the request payload contains no such object as the struct C for instance like below
{
"title": "First message from GoLang",
"text": "Hello Dastgyr",
"data": {
"external_link": "some link here"
//no product object (C struct) here
}
}
The object inserted into Mongo still contains the struct C as having a null value as shown below
{
"title": "First message from GoLang",
"text": "Hello Dastgyr",
"data": {
"product": null,
"external_link": "some link here"
}
}
I've also tried using B as a pointer in Struct A but to no avail
type A struct {
Title string `json:"title"`
Text string `json:"text"`
Data *B `json:"data,omitempty"`
}
I want to be able to omit certain nested structs. Despite using pointers, the struct I want is still not omitting. What mistake am I making in defining structs?
Still new to golang so a nudge in the right direction would help
You are using json tags for json un-marshaling, it seems to be un-marshaling correctly (concluding this as you didn't mention any errors, and moved on to MongoDB)
How you add data to MongoDB is a totally different matter, and has nothing to do with your JSON tags. It uses bson tags, and you will need to add them, if you wish to use this same struct as a mongo DB model representation. Something like this:
type A struct {
Title string `json:"title" bson:"title"`
Text string `json:"text" bson:"text"`
Data *B `json:"data,omitempty" bson:"data,omitempty"`
}
Remember that tags in golang, are just some metadata being added with a structure, which some code actually reads and acts on. json library identifies & processes json:"" tag, while official go mongodb library that you might be using, will process the bson:"" tags.
I have some JSON that get via an API call and I want to now parse this using JSON, I followed an online tutorial in how to parse JSON using structs, but my actual JSON is a lot more complex than the one they used. Here is an example of the JSON I have:
{
"metadata": {},
"items": [
{
"metadata": {
"name": "run7",
"namespace": "default",
"uid": "e218fcc4",
"creationTimestamp": "2022-01-01T00:00:00Z"
},
"spec": {
"arguments": {}
},
"status": {
"phase": "Succeeded",
"startedAt": "2022-01-01T00:00:00Z",
"finishedAt": "2022-01-01T00:00:00Z"
}
}
]
}
and here is the strucs that I created for it:
type wfSpec struct{
Arguments string
}
type wfStatus struct {
Phase string
StartedAt string
FinishedAt string
}
type wfMetadata struct {
Name string
Namespace string
Uid string
CreationTimestamp string
}
type Metadata []struct {
Data string
}
type Items []struct {
wfMetadata
wfStatus
wfSpec
}
type Workflow struct {
Metadata Metadata
Items Items
}
When I first tried to print a value using fmt.Printf(workflows.Items.wfMetadata.Name) I got the error workflows.Items.Metadata undefined (type Items has no field or method Metadata)so then I tried to just print the whole thing using fmt.Printf(workflows) and I got this error cannot use workflows (type Workflow) as type string in argument to fmt.Printf
The only data I need to parse from the JSON is the
"name": "run7",
"namespace": "default",
"uid": "e218fcc4",
"creationTimestamp": "2022-01-01T00:00:00Z"
First off
The problem I expect you're having is not using the tags. To parse a JSON the names of the structs must match the names in the JSON fields. Read here Golang Marshal
Secondly wfMetadata has a lowecase first letter, meaning it will not be imported.
Thirdly, workflow.metadata and workflow.items[i].spec.arguments is set as a {} and not the emptystring "". I assume they're not supposed to be string. This can be avoided using the open interface{} if you don't know or care, or actually implementing them using the official documentations from the API you're connecting to.
As a note, using []struct seems wrong to me. Instead define it in the usage
Note, by using an IDE like GoLand from jetbrains they first off support converting JSON to a struct by simply pasting the JSON into a .go file. They might be daunting at first but do help a lot, and would do much of this for you in seconds.
Now try this instead, and understand why and how this is better and working.
type Status struct {
Phase string `json:"phase"`
StartedAt string `json:"startedAt"`
FinishedAt string `json:"finishedAt"`
}
type ItemMetadata struct {
Name string `json:"name"`
Namespace string `json:"namespace"`
UID string `json:"uid"`
CreationTimestamp string `json:"creationTimestamp"`
}
type Items struct {
Metadata ItemMetadata `json:"metadata"`
Status Status `json:"status"`
Spec interface{} `json:"spec"`
}
type Workflow struct {
Metadata interface{} `json:"metadata"`
Items []Items `json:"items"`
}
Working example in playground https://go.dev/play/p/d9rT4FZJsGv
I've just started studying Golang and don't understand how to write only specific JSON fields to an output file.
For example I have this struct:
type example struct {
Ifindex int `json:"ifindex"`
HostID int `json:"host_id"`
Hostname string `json:"hostname"`
Name string `json:"name"`
}
My output file should be in the following format:
[{"Ifindex": int, "Hostname": string}, {...}]
How can I do it?
If I understood correctly, you'd like to omit some of the fields when marshalling to JSON. Then use json:"-" as a field tag.
Per the json.Marshal(...) documentation:
As a special case, if the field tag is "-", the field is always omitted.
So you just need to use the tag "-" for any public field that you do not want serialized, for example (Go Playground):
type Example struct {
Ifindex int `json:"ifindex"`
HostID int `json:"-"`
Hostname string `json:"hostname"`
Name string `json:"-"`
}
func main() {
eg := Example{Ifindex: 1, HostID: 2, Hostname: "foo", Name: "bar"}
bs, err := json.Marshal(&eg)
if err != nil {
panic(err)
}
fmt.Println(string(bs))
// {"ifindex":1,"hostname":"foo"}
}
I can't decode the json code below ... any ideas why it doesn't work ? See also play.golang
package main
import (
"encoding/json"
)
type LocationReadable struct {
District string
City string
State string
}
type Locale struct {
Location string
CountryCode string
CurrencyId string
CurrencySymbol string
LocationReadable LocationReadable
}
type Media struct {
Image string
Video string
}
type Variations struct {
FixedPrice float64
Media Media
Quantity int
}
type PaymentData struct {
PaymentName string
PaymentService string
}
type Payment struct {
Online PaymentData
Offline PaymentData
}
type Shipping struct {
ShippingService string
ShippingName string
ShippingCost float64
HandlingTimeMax int
DispatchTimeMin int
DispatchTimeMax int
ShippingAdditionalCost int
}
type Item []struct {
_version string
CategoryId string
Title string
Media Media
SellerId string
Locale Locale
ListingType string
Payment Payment
StartTime string
EndTime string
Shipping Shipping
TitleSlug string
Variations Variations
_fpaiStatus string
}
func main() {
itemInfoR := `{"locale":{"location":"51.51121389999999,-0.11982439999997041","countryCode":"GB","currencyId":"GBP","currencySymbol":"£","locationReadable":{"district":"City of Westminster","city":"London","state":"Greater London"}},"_version":"serving","categoryId":["Root","Cameras \u0026 Photo","Digital Cameras"],"title":"many pictures","media":{"image":["//lh5.ggpht.com/O_o_N6CFkClY5AV0-LqntpyFjor7Of4u23ZcK7lYwc2uY1ea7GWi61VDJZCB7UCb79svkjKPHIenqwEUhjHi0jdIQnnl6z_p03yktPUB1FBHezIQ","//lh6.ggpht.com/ih3q2d7CenGLPyupH9FpfsoJQWQpw1i8wWA2Kd26bFnSF2fbnKyGU9WePIhCgEeqw5p6YMVmFi1c9oS0Ag93aF_oZ3ZiwK7fQuSYIrZ9VhgXbrTHkw","//lh6.ggpht.com/7RJRsapsnwWL3_KiLIjMz4QojDzUvsztXtvKTFvIfde_AHccDnOibAvXRN73tTB4SeHzlj8S1LWxbYwwWFGn9elfCKdSb8BUIU5QJY1LO791HutQ","//lh6.ggpht.com/qAtjgyHAB734Ox_4NC_fa-ZRqrCjCmJu0Tp8bo-HMO88duv8l4hhuv2REBkB--yneFzOL7annecVlGty-YsKouondiOFVnAZWzjpdrfsGfbL6wh2","//lh3.ggpht.com/dWUbASepwHF4lHaXIPnpv4BNm2pCml9MlJt7s86s1cpu-PsYNmS0yQmKFKTM38q_oMLW_YJMJ19civ2gVViKAGYcZylRW7jN3w77AJvhzS6JE2g","//lh6.ggpht.com/9aXLmPRVeZnxkwvNb3mWTF8kvfEY_lho_lOVVc9AbNqLb8GQmiS_XXVZ3OKqMv2pxgYSayMYPPRh6ACYyh0H8KtS8mPD6MKUkEajwxkTtp5Q4Lo","//lh3.ggpht.com/FG_QXZPHJ2tTYwI_t5Fg1KqivglVg9RlJn0JRsu9Ox8vJ7IcBirb2IV_I1LL_WVOMxfTuBBSDLMlrw9v0MCAdmnPCR29sCbRGjhm6zEfIH-3q2QSdw","//lh4.ggpht.com/Y23DqORrVkM2m55f-rq5_BBrlkvQg4uX7AsAt-ixhMobjK_SFgFaDfktgLhkNsyKwSr9HcF8iiGY3Nw0xOKXG1sn6wyAWg_qsolmKjVOrM5V5mIR","//lh6.ggpht.com/mQ62Ly-DjMKPMzU1OcSPJ7SLBqym0uBjawlkTHfmb-HOKaD56dnitk1duwPFJVdbi0GUpd63RQvr2VMpHp6S1OQ3di-hq4-JPeRoS5FJzksXSvW_","//lh3.ggpht.com/dqWjWPcNsvlR1tMC_agizX19f9MDiNGWFYTYVn4kjJxzIIkEe0mLzNcvS62zVJxAOaitT-IgaUfZ-Ze23BgzbqYY-l600i_LbVe35Uinz6sXIyoB","//lh6.ggpht.com/xhSdFc9uHgghs_6gf3seUWYM-PG2oLmjTrpF7ptEEMqaIrQIa8VPfC6tXE7f3M13eZvDXYqMW_k0AHO5vwCEPNp-iObixskd_lBaKNfz3MH3SNQ","//lh5.ggpht.com/kYeoKPoZGJCow-G1FhnD8kzVjNjbQA8-Kyj8eAh0HL-fMZX9tTeFPQikTZdSU0kks4-5Ui54cZF2CjGut9vfMJAVDKIq3T-bAQewCxvfl2120tH5zQ","//lh5.ggpht.com/4qUl3d-G9EPBzcYKrimNsWhQw7CmONV0jgfVhxFgB9mEU_QLRCyNJTWs2A3xf6wc7AUF2DXrKEkoX-SNLMZ6s-O4aXXV9WOjOPcWdAYreMRBld0E","//lh5.ggpht.com/z-0C4G6EWYkelAF1LjPfl_UQcsp92H4joIPt8NfsOl0nPJ2VpzZYahWadKqTLfl6kq3C6aDBcwfGQyMWSozYoZIAOAW0yRvZrwxia321PlsKTxbZ","//lh4.ggpht.com/U7I12JrDYmMC_pUXpw8DVBjBilU67BvbM8qT8gJE0bQfkhHo7FOdMttiz3syP5IR-LyO4J1WBlfmZjvMjRr4GIBt4o3Vqp-hKz7q2_OGwGtsN5s","//lh3.ggpht.com/fF2XWEtqG23ybhzClhC_p8gvKJalf1vg7k3H7UkuAaIVubil7EgOvJUCwAZk2KiCtlPYp1E5Ep2xaxZjJRmg5EFSEAjqlMHJS_Wd1Bcje6xre4s","//lh3.ggpht.com/jgOebMihBoIZvHE4EOklJvZ_k-9egjNIlUKfKFcLkvXJs8g2FXjPvdFUbwqGrkHrMtyis8uOvgt-E51Vm11hq4bieh7h0cegca0VI4vFtFaAemU","//lh3.ggpht.com/MOrI-zKNMNrQE_aHj5hzbojP3T0hEMJKK6K8UO3e1NBC-nkcQeIM1QnvtJdT_G-W4e7-qv4BiqwdWcNHBpZXOmmX3tcuYEV8u_ANEoa9_aUIfeyg","//lh6.ggpht.com/SyIS5sGOkTG7k_jFF14wzH9Evrblv6o4pHBI6z6X070-xhAeyut_kRO6xHtDID4KLcWFvItjQy-plPcJ6K1T9tlFOrtaryEPvuAYdMVx8e0TTw","//lh6.ggpht.com/2Pp9kLYFhDT3USwHinU5OxnzcWWOLI0nOWe29gOD5KMzyEcXoHkTN-AutJV9M8F_9eqAP379XB9O1d0BWPanhr-MguzKxfHeUvYTs6yHzDkxyfe0NA","//lh4.ggpht.com/7aofqklSkF3AMDfF19yqsA9J3EfEiKy1NdOelEGKNnW0Cv5tGEpq2PF_jZO1MVoBbrrmVVRv0Tdq7I8KyZbIlyHdbTs1jMl7dEFqVMvsPcyaORyHlQ","//lh4.ggpht.com/anYJHqkMCkuhmIHQTBspLtWcDTyx1ZRe84_q5pAgVEOVmsKkaKhS725N4YFoj2zpJrBP7iTC2vf1GUtrp6H7kkm8c1k6zkW6I_Gf5f9A3re_I8Ex","//lh3.ggpht.com/OtSw0rU-DvfoXgoWrQdkln6Kz7O14TF9qrPNJSGJnZLeDqUEctOn1DT09pdwwVpNQV-cXmVYQL-PX4XPhpZLWH1ciSkVT6WHNmTz1D9pHphBwJUv","//lh3.ggpht.com/cTCZnXPIjI-EO2bvQdLgeoSLOSlMFcv805n347Zyci9XDYUdcVDC_5H7SFVYDr4pC5HtQDYnrOHL6AinLW7hWtfSCLlvVhVUNQ-DlDn0NwZ-1iCO-g","//lh4.ggpht.com/i-mL_JcF9rwjQq6HnuKzuAHU41_UGxQ62IOPZvaDrATXaPFbhe-EbT7ZIpboyNA5PXRCsxNsZ9hu58edRvNs5ScgKN8Lg-00J2LhlwMAbdEsv7b0nw","//lh6.ggpht.com/D_YV2BG1WWwl67xNloP3sxzRkqhcVTgJi58L-A8nLrOcMR_tBqLz4fHEGQ-qiNcG_-32MNy3dlSPWrTBKzBcweJxgMnRVet5yuGfelUlwehDtXX_3w"],"video":[]},"sellerId":"mihai","listingType":"fixedPrice","payment":{"online":[{"paymentName":"PayPal","paymentService":"paypal"}],"offline":[{"paymentName":"Pay on Pick-up","paymentService":"payOnPickup"}]},"startTime":"2014-01-04T10:02:18+00:00","endTime":"2014-04-04T10:02:18+00:00","shipping":[{"shippingService":"economy","shippingName":"Economy","shippingCost":1.0,"handlingTimeMax":4,"dispatchTimeMin":1,"dispatchTimeMax":10,"shippingAdditionalCost":"2"},{"shippingService":"localPickup","shippingName":"Local Pick-Up","shippingCost":0.0,"handlingTimeMax":2,"dispatchTimeMin":0,"dispatchTimeMax":0,"shippingAdditionalCost":"0"}],"titleSlug":"many-pictures","variations":[{"fixedPrice":222999.0,"media":{"image":["//lh6.ggpht.com/ih3q2d7CenGLPyupH9FpfsoJQWQpw1i8wWA2Kd26bFnSF2fbnKyGU9WePIhCgEeqw5p6YMVmFi1c9oS0Ag93aF_oZ3ZiwK7fQuSYIrZ9VhgXbrTHkw","//lh6.ggpht.com/9aXLmPRVeZnxkwvNb3mWTF8kvfEY_lho_lOVVc9AbNqLb8GQmiS_XXVZ3OKqMv2pxgYSayMYPPRh6ACYyh0H8KtS8mPD6MKUkEajwxkTtp5Q4Lo","//lh3.ggpht.com/FG_QXZPHJ2tTYwI_t5Fg1KqivglVg9RlJn0JRsu9Ox8vJ7IcBirb2IV_I1LL_WVOMxfTuBBSDLMlrw9v0MCAdmnPCR29sCbRGjhm6zEfIH-3q2QSdw"],"video":[]},"quantity":1121,"Brand":"Bell \u0026 Howell"},{"fixedPrice":211.0,"media":{"image":["//lh6.ggpht.com/qAtjgyHAB734Ox_4NC_fa-ZRqrCjCmJu0Tp8bo-HMO88duv8l4hhuv2REBkB--yneFzOL7annecVlGty-YsKouondiOFVnAZWzjpdrfsGfbL6wh2","//lh3.ggpht.com/FG_QXZPHJ2tTYwI_t5Fg1KqivglVg9RlJn0JRsu9Ox8vJ7IcBirb2IV_I1LL_WVOMxfTuBBSDLMlrw9v0MCAdmnPCR29sCbRGjhm6zEfIH-3q2QSdw","//lh6.ggpht.com/9aXLmPRVeZnxkwvNb3mWTF8kvfEY_lho_lOVVc9AbNqLb8GQmiS_XXVZ3OKqMv2pxgYSayMYPPRh6ACYyh0H8KtS8mPD6MKUkEajwxkTtp5Q4Lo","//lh3.ggpht.com/MOrI-zKNMNrQE_aHj5hzbojP3T0hEMJKK6K8UO3e1NBC-nkcQeIM1QnvtJdT_G-W4e7-qv4BiqwdWcNHBpZXOmmX3tcuYEV8u_ANEoa9_aUIfeyg"],"video":[]},"quantity":2,"Brand":"Fujifilm"},{"fixedPrice":22.0,"media":{"image":["//lh3.ggpht.com/jgOebMihBoIZvHE4EOklJvZ_k-9egjNIlUKfKFcLkvXJs8g2FXjPvdFUbwqGrkHrMtyis8uOvgt-E51Vm11hq4bieh7h0cegca0VI4vFtFaAemU","//lh3.ggpht.com/MOrI-zKNMNrQE_aHj5hzbojP3T0hEMJKK6K8UO3e1NBC-nkcQeIM1QnvtJdT_G-W4e7-qv4BiqwdWcNHBpZXOmmX3tcuYEV8u_ANEoa9_aUIfeyg","//lh4.ggpht.com/anYJHqkMCkuhmIHQTBspLtWcDTyx1ZRe84_q5pAgVEOVmsKkaKhS725N4YFoj2zpJrBP7iTC2vf1GUtrp6H7kkm8c1k6zkW6I_Gf5f9A3re_I8Ex"],"video":[]},"quantity":12,"Brand":"Gateway"}],"_fpaiStatus":"published"}`
itemInfoBytes := []byte(itemInfoR)
var ItemInfo Item
er := json.Unmarshal(itemInfoBytes, &ItemInfo)
if er != nil {
panic(er)
}
}
Here's a fixed version of it: http://play.golang.org/p/w2ZcOzGHKR
The biggest fix that was needed is when Unmarshalling an array, that property needs to be an array/slice in the struct as well.
For example:
{ "things": ["a", "b", "c"] }
Would Unmarshal into a:
type Item struct {
Things []string
}
And not into:
type Item struct {
Things string
}
The other thing to watch out for when Unmarshaling is that the types line up exactly. It will fail when Unmarshalling a JSON string representation of a number into an int or float field -- "1" needs to Unmarshal into a string, not into an int like we saw with ShippingAdditionalCost int
Determining of root cause is not an issue since Go 1.8; field name now is shown in the error message:
json: cannot unmarshal object into Go struct field Comment.author of type string
You JSON doesn't match your struct fields: E.g. "district" in JSON and "District" as the field.
Also: Your Item is a slice type but your JSON is a dict value. Do not mix this up. Slices decode from arrays.
Just in case you're looking for an answer to this from an AWS perspective, particularly if you're trying to use UnmarshalListOfMaps() on the items coming back from a DynamoDB query(), then watch out for a simple typo I made.
Given that this function UnmarshalListOfMaps() takes in...a list of maps :-) then it needs to unmarshal into a List of whatever struct you're trying to build, and not just the plain struct itself. This was throwing me off because I was trying to start by querying for something that should only return one row.
movie := Movie{}
// Run the DynamoDB query
resp, err := session.Query(input) // type QueryInput
if err != nil {
log.WithError(err).Error("Error running DynamoDB query")
}
// Unmarshal all the attribute values into a Movie struct
err = dynamodbattribute.UnmarshalListOfMaps(resp.Items, &movie); if err != nil {
log.WithError(err).Error("Error marshaling DynamoDB result into Movie")
return link, err
}
The problem is in the first line. It should be movies := []Movie{} and then the reference &movie needs to change to &movies as well. If you leave it just as it is above, then the AWS Go SDK will throw this error:
cannot unmarshal list into Go value of type (etc).
If you ever face this while typing yml file not copy-pasting, it might be a problem with your yml file - mine was wrong indent.
This happened while making pipeline on concourse.