A struct tag is a string literal (because it has the string type)
Key is an unquoted string literal
Value is a quoted string literal
Key and value are separated by a colon (:). A key together with a value, separated by the colon is called a “key value pair“
A struct tag can contain multiple key value pairs (optional). The key-value pairs are separated by a space.
Not part of the definition is the options setting. Packages like encoding/json read the value as a comma-separated list. Anything after the first comma is part of the options, i.e: “foo,omitempty,string“. Here the value has a name called “foo” and options [“omitempty”, “string”]
Because the struct tag is a string literal, it needs to be quoted either with a double quote or backtick. Because the value has to be quoted as well we always use backticks.

参考资料

The ultimate guide to writing a Go tool

Tags in Golang

Go Tags explained

最后修改于 2019-03-28