英文:
golang convert array of interfaces to strings
问题
我从远程源读取JSON数据并将其转换为映射。数据中有一些数组，我想检查字符串值。在转换后，我认为m["t"]是一个接口数组。fmt.Print将其转换为在控制台上打印的文本，但我无法找到一种简单的方法来进行字符串比较，例如：
if val[0] == "str-c" {fmt.Println("success")}
如何遍历该数组并进行字符串比较？
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)
// 找出"t"的字符串值中是否有"str-b"
tArray := m["t"].([]interface{})
for _, val := range tArray {
if val.(string) == "str-b" {
fmt.Println("success")
break
}
}
}
以上是你提供的代码的修改版，可以遍历数组并进行字符串比较。
英文:
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"])
}
答案1
得分: 9
m["t"]的类型是interface{}，它是完整的数组。如果你想获取str-b，它位于索引为1的位置，你需要进行一些类型断言将其转换为字符串。这里有一个示例：https://play.golang.org/p/W7ZnMgicc7
如果你想在集合中检查它，可以这样做：
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)
// 判断 "t" 中是否有字符串值为 "str-b"
for _, v := range m["t"].([]interface{}) {
if v.(string) == "str-b" {
fmt.Println("找到匹配！")
}
}
//fmt.Println(m["t"].([]interface{})[1].(string))
}
https://play.golang.org/p/vo_90bKw92
如果你想避免这种“拆箱”操作，我建议你定义一个结构体进行解组，代码如下：
type MyStruct struct {
K string `json:"k"`
T []string `json:"t"`
}
然后你可以直接遍历T，无需进行任何类型断言并进行比较。这里有一个可运行的示例：https://play.golang.org/p/ehPxOygGf5
英文:
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
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