在golang结构定义中，backtick的用法是什么？ [重复]

Question

This question already has an answer here:

• Strange type definition syntax in Golang (name, then type, then string literal) 1 answer

type NetworkInterface struct {
    Gateway              string `json:"gateway"`
    IPAddress            string `json:"ip"`
    IPPrefixLen          int    `json:"ip_prefix_len"`
    MacAddress           string `json:"mac"`
    ...
}

I'm quite confused what's the function of contents in backtick, like json:"gateway".

Is it just comment, like //this is the gateway?

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Answer 1

You can add extra meta information to Go structs in the form of tags. Here are some examples of use cases.

In this case, the json:"gateway" is used by the json package to encode the value of Gateway into the key gateway in the corresponding json object.

Example:

n := NetworkInterface{
   Gateway : "foo"
}
json.Marshal(n)
// will output `{"gateway":"foo",...}`