golang convert array of interfaces to strings - json

Question

I read JSON data from a remote source and convert it to a map. There's some array in the data of which I want to examine the string values. After converting I think m["t"] is an array of interfaces. fmt.Print converts this to printed text on the console but I cannot figure a way to do a simple string comparison like
if val[0] == "str-c" {fmt.Println("success")}
How do I iterate through that and do string comparisons?
package main
import (
"fmt"
"encoding/json"
)
func main() {
var m map[string]interface{}
sJSON := `{"k": "v", "t":["str-a","str-b","str-c"]}`
_ = json.Unmarshal([]byte(sJSON),&m)
// find out if one of the string values of "t" is "str-b"
fmt.Println(m["t"])
}

Answer 1

m["t"] is of type interface{} and is the full array, if you wanted to get str-b it is at index one and you have to do some type assertion to get it as a string. Here's an example; https://play.golang.org/p/W7ZnMgicc7
If you want to check for it in the collection that would look like this;
package main
import (
"fmt"
"encoding/json"
)
func main() {
var m map[string]interface{}
sJSON := `{"k": "v", "t":["str-a","str-b","str-c"]}`
_ = json.Unmarshal([]byte(sJSON),&m)
// find out if one of the string values of "t" is "str-b"
for _, v := range m["t"].([]interface{}) {
if v.(string) == "str-b" {
fmt.Println("match found!")
}
}
//fmt.Println(m["t"].([]interface{})[1].(string))
}
https://play.golang.org/p/vo_90bKw92
If you want to avoid this 'unboxing' stuff, which I would recommend you do, you could instead define a struct to unmarshal into, itwould look like this;
type MyStruct struct {
K string `json:"k"`
T []string `json:"t"`
}
Then you can just range over T without any type assertions and do the compare, working example here; https://play.golang.org/p/ehPxOygGf5