如何在Golang保存到MongoDB时排除空数据值的问题

我是Golang的新手，我面临着将数据保存到数据库的问题.在从API接收到JSON对象后，我试图将其存储在MongoDB中，但数据被保存为空值.

下面是我的代码和 struct :

var current:={
    "usd": {
        "code": "USD",
        "alphaCode": "USD",
        "numericCode": "840",
        "name": "U.S. Dollar",
        "rate": 0.68135437808647,
        "date": "Sun, 31 Dec 2023 11:55:01 GMT",
        "inverseRate": 1.4676650391657
    },
    "eur": {
        "code": "EUR",
        "alphaCode": "EUR",
        "numericCode": "978",
        "name": "Euro",
        "rate": 0.61624276207684,
        "date": "Sun, 31 Dec 2023 11:55:01 GMT",
        "inverseRate": 1.6227371119619
    },
    "gbp": {
        "code": "GBP",
        "alphaCode": "GBP",
        "numericCode": "826",
        "name": "U.K. Pound Sterling",
        "rate": 0.53541690218052,
        "date": "Sun, 31 Dec 2023 11:55:01 GMT",
        "inverseRate": 1.8677034586085
    }
}

这是我的模特.go 吧

type Currency struct {
    Code        string  `json:"code"`
    AlphaCode   string  `json:"alphaCode"`
    NumericCode string  `json:"numericCode"`
    Name        string  `json:"name"`
    Rate        float64 `json:"rate"`
    Date        string  `json:"date"`
    InverseRate float64 `json:"inverseRate"`
}

type Rate struct {
    ID        primitive.ObjectID `json:"_id,omitempty" bson:"_id,omitempty"`
    Currency  `json:"currency"`
    Timestamp primitive.DateTime `json:"timestamp"`
}

我try 将数据保存到数据库，但我只写入默认值，其中包含空字符串和0

const apiUrl = "https://www.floatrates.com/daily/aud.json" 
func GetRatesFromAPI() (map[string]models.Rate, error) {
    response, err := http.Get(apiUrl)
    fmt.Print(response)
    if err != nil {
        return nil, err
    }
    defer response.Body.Close()

    body, err := ioutil.ReadAll(response.Body)
    if err != nil {
        return nil, err
    }

    var data map[string]models.Rate
    if err := json.Unmarshal(body, &data); err != nil {
        return nil, err
    }
    fmt.Print(data)
    return data, nil
}
    r.GET("/get", func(c *gin.Context) {
      mongo.ConnectDB()
          rates, err := src.GetRatesFromAPI()
      fmt.Print(rates)
          if err != nil {
        log.Fatal(err)
      }
      for _, rate := range rates {
        mongo.InsertRate(rate)
       }

      c.String(http.StatusOK, "get rates")
    })
func InsertRate(rate models.Rate) {
    rate.Timestamp = primitive.NewDateTimeFromTime(time.Now())
    collection := client.Database("mongodb").Collection("rates")
    ctx, cancel := context.WithTimeout(context.Background(), 5*time.Second)
    defer cancel()

    result, err := collection.InsertOne(ctx, rate)
    if err != nil {
        log.Fatal(err)
    }

    log.Println("Inserted rate with ID:", result.InsertedID)
}

我在DB中获取这个对象时没有任何值，我试图找出为什么数据没有正确存储在MongoDB中.如有任何帮助或建议，我们将不胜感激！

[
  {
    "_id": {"$oid": "659177abefa699e213158c16"},
    "currency": {
      "code": "",
      "alphacode": "",
      "numericcode": "",
      "name": "",
      "rate": 0,
      "date": "",
      "inverserate": 0
    },
    "timestamp": {"$date": "2023-12-31T14:16:11.800Z"}
  }
]