在特定结构中解组 Json 数据
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Unmarshal Json data in a specific struct
提问by ungchy
I want to unmarshal the following JSON data in Go:
我想在 Go 中解组以下 JSON 数据：
b := []byte(`{"Asks": [[21, 1], [22, 1]] ,"Bids": [[20, 1], [19, 1]]}`)
I know how to do that, i define a struct like this:
我知道怎么做，我定义了一个这样的结构：
type Message struct {
Asks [][]float64 `json:"Bids"`
Bids [][]float64 `json:"Asks"`
}
What i don't know is if there is a simple way to specialize this a bit more. I would like to have the data after the unmarshaling in a format like this:
我不知道是否有一种简单的方法可以专门研究这一点。我想在解组后以这样的格式获得数据：
type Message struct {
Asks []Order `json:"Bids"`
Bids []Order `json:"Asks"`
}
type Order struct {
Price float64
Volume float64
}
So that i can use it later after unmarshaling like this:
这样我就可以在像这样解组后使用它：
m := new(Message)
err := json.Unmarshal(b, &m)
fmt.Println(m.Asks[0].Price)
I don't really know how to easy or idiomatically do that in GO so I hope that there is a nice solution for that.
我真的不知道如何在 GO 中轻松或惯用地做到这一点，所以我希望有一个很好的解决方案。
回答by James Henstridge
You can do this with by implementing the json.Unmarshalerinterfaceon your Orderstruct. Something like this should do:
您可以通过在结构上实现json.Unmarshaler接口来做到这一点Order。这样的事情应该做：
func (o *Order) UnmarshalJSON(data []byte) error {
var v [2]float64
if err := json.Unmarshal(data, &v); err != nil {
return err
}
o.Price = v[0]
o.Volume = v[1]
return nil
}
This basically says that the Ordertype should be decoded from a 2 element array of floats rather than the default representation for a struct (an object).
这基本上是说Order应该从浮点数的 2 元素数组而不是结构（对象）的默认表示中解码类型。
You can play around with this example here: http://play.golang.org/p/B35Of8H1e6
你可以在这里玩这个例子：http: //play.golang.org/p/B35Of8H1e6
