英文:
panic: interface conversion: interface {} is string, not float64
问题
你在将这个简单的 Python 函数转换为 Golang 时遇到了问题。错误信息是 panic: interface conversion: interface {} is string, not float64。
以下是 Python 代码：
def binance(crypto: str, currency: str):
import requests
base_url = "https://www.binance.com/api/v3/avgPrice?symbol={}{}"
base_url = base_url.format(crypto, currency)
try:
result = requests.get(base_url).json()
print(result)
result = result.get("price")
except Exception as e:
return False
return result
以下是 Golang 代码（比应有的代码更长且更复杂）：
func Binance(crypto string, currency string) (float64, error) {
req, err := http.NewRequest("GET", fmt.Sprintf("https://www.binance.com/api/v3/avgPrice?symbol=%s%s", crypto, currency), nil)
if err != nil {
fmt.Println("Error is req: ", err)
}
client := &http.Client{}
resp, err := client.Do(req)
if err != nil {
fmt.Println("error in send req: ", err)
}
respBody, _ := ioutil.ReadAll(resp.Body)
var respMap map[string]interface{}
log.Printf("body=%v",respBody)
json.Unmarshal(respBody,&respMap)
log.Printf("response=%v",respMap)
price := respMap["price"]
log.Printf("price=%v",price)
pricer := price.(float64)
return pricer, err
}
你在这里出了什么问题？之前你遇到了错误 cannot use price (type interface {}) as type float64 in return argument: need type assertion，然后你尝试了类型断言 pricer := price.(float64)，现在又出现了这个错误 panic: interface conversion: interface {} is string, not float64。
请注意，Golang 中的类型断言是一种将接口类型转换为具体类型的操作。在这种情况下，你尝试将 price 接口类型转换为 float64 类型，但实际上 price 是一个字符串类型。
这是因为在 Python 代码中，result.get("price") 返回的是一个字符串，而不是一个浮点数。因此，在 Golang 代码中，你需要将 price 的类型断言为字符串类型，而不是浮点数类型。你可以使用 price.(string) 进行类型断言。
修正后的 Golang 代码如下：
func Binance(crypto string, currency string) (string, error) {
req, err := http.NewRequest("GET", fmt.Sprintf("https://www.binance.com/api/v3/avgPrice?symbol=%s%s", crypto, currency), nil)
if err != nil {
fmt.Println("Error is req: ", err)
}
client := &http.Client{}
resp, err := client.Do(req)
if err != nil {
fmt.Println("error in send req: ", err)
}
respBody, _ := ioutil.ReadAll(resp.Body)
var respMap map[string]interface{}
log.Printf("body=%v",respBody)
json.Unmarshal(respBody,&respMap)
log.Printf("response=%v",respMap)
price := respMap["price"]
log.Printf("price=%v",price)
pricer := price.(string)
return pricer, err
}
这样，你应该能够正确地将 price 转换为字符串类型并返回它，而不会出现类型转换错误。
英文:
I am trying to convert this simple python function to golang, but facing issues with this error
panic: interface conversion: interface {} is string, not float64
python
def binance(crypto: str, currency: str):
import requests
base_url = "https://www.binance.com/api/v3/avgPrice?symbol={}{}"
base_url = base_url.format(crypto, currency)
try:
result = requests.get(base_url).json()
print(result)
result = result.get("price")
except Exception as e:
return False
return result
here is the golang version(longer code and more complicated code than should be)
func Binance(crypto string, currency string) (float64, error) {
req, err := http.NewRequest("GET", fmt.Sprintf("https://www.binance.com/api/v3/avgPrice?symbol=%s%s", crypto, currency), nil)
if err != nil {
fmt.Println("Error is req: ", err)
}
client := &http.Client{}
resp, err := client.Do(req)
if err != nil {
fmt.Println("error in send req: ", err)
}
respBody, _ := ioutil.ReadAll(resp.Body)
var respMap map[string]interface{}
log.Printf("body=%v",respBody)
json.Unmarshal(respBody,&respMap)
log.Printf("response=%v",respMap)
price := respMap["price"]
log.Printf("price=%v",price)
pricer := price.(float64)
return pricer, err
}
so what am I getting wrong here? Previously i had the error cannot use price (type interface {}) as type float64 in return argument: need type assertion and now i tried the type assertion with pricer := price.(float64) and now this error
panic: interface conversion: interface {} is string, not float64
答案1
得分: 5
在错误信息中告诉你，price 是一个字符串，而不是一个 float64 类型，所以你需要进行如下操作（假设）：
pricer := price.(string)
return strconv.ParseFloat(pricer, 64)
更好的方法可能是使用以下方式：
type response struct {
Price float64 `json:",string"`
}
r := &response{}
respBody, _ := ioutil.ReadAll(resp.Body)
err := json.Unmarshal(respBody, r)
return r.Price, err
"string" 选项表示该字段以 JSON 形式存储在 JSON 编码的字符串中。它仅适用于字符串、浮点数、整数或布尔类型的字段。
参考链接：https://pkg.go.dev/encoding/json#Marshal
英文:
It's telling you in the error, price is a string, not a float64, so you need to do (presumably):
pricer := price.(string)
return strconv.ParseFloat(pricer, 64)
A better way would probably be to instead do
type response struct {
Price float64 `json:",string"`
}
r := &response{}
respBody, _ := ioutil.ReadAll(resp.Body)
err := json.Unmarshal(respBody, r)
return r.Price, err
> The "string" option signals that a field is stored as JSON inside a JSON-encoded string. It applies only to fields of string, floating point, integer, or boolean types.
答案2
得分: 3
错误已经告诉你了：price 是一个字符串。所以它可能来自一个看起来像这样的 JSON：
{
"price": "123"
}
而不是
{
"price": 123
}
第一个解析为字符串。第二个解析为 float64。
在你的情况下，你需要解析它：
pricer, err := strconv.ParseFloat(price.(string), 64)
英文:
The error already tells you: price is a string. So it is probably coming from a JSON that looks like:
{
"price": "123"
}
but not
{
"price": 123
}
The first unmarshals as string. The second unmarshals as float64.
In your case, you have to parse it:
pricer,err := strconv.ParseFloat(price.(string),64)
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