Getting custom Azure AD B2C user attributes

get_azure_adb2c_user_attributes.go

/*****
import (
  "context"
  "encoding/json"
  "errors"
  "fmt"
  "io/ioutil"
  "net/http"
  "strings"
)
*****/


// The user attributes we are interested in should be given in the path.
// The custom attributes include B2C extension app ID in their name.
path := "https://graph.microsoft.com/v1.0/" + tenantID + "/users/" + userID +
  "?$select=userPrincipalName," +
  "extension_" + extensionID + "_PrivateKey," +
  "extension_" + extensionID + "_PublicKey"

r, err := http.NewRequestWithContext(ctx, http.MethodGet, path, nil)
if err != nil {
  panic(err)
}
// make sure to use a valid token
r.Header.Add("Authorization", "Bearer "+token)

resp, err := http.DefaultClient.Do(r)
if err != nil {
  panic(err)
}

defer resp.Body.Close()
reponseBody, err := ioutil.ReadAll(resp.Body)
if err != nil {
  panic(err)
}

if !isResponseSuccess(resp.StatusCode) {
  if resp.StatusCode == http.StatusUnauthorized {
    // if unauthorized, normally you would request a new token and try again
    panic(err)
  }

  panic("status code: " + resp.Status + "; error details: " + string(responseBody))
}

// Now we want to read the response using the json library
// but if we know the extensions app ID only in the runtime, 
// we can't use it in the struct tag as we normally would do.
// That's why first we want to remove the extensions app ID from the response.
modifiedBody := strings.ReplaceAll(string(reponseBody), "extension_" + extensionID + "_", "")

// Finally we can parse the response using the known attribute names.
var unmarshalled struct {
  Name       string `json:"userPrincipalName"`
  PrivateKey string `json:"PrivateKey"`
  PublicKey  string `json:"PublicKey"`
}
if err := json.Unmarshal([]byte(modifiedBody), &unmarshalled); err != nil {
  panic(err)
}

fmt.Println(unmarshalled.PublicKey)