When you type this question ( Add constants for Content-Type in GO? ) in google, the first answer will get this

proposal: net/http: add constant for content type · Issue #31572 · golang/go

Is it a good idea to add constants for content type of HTTP body like http.MethodPost in HTTP methods? It might be const ( ContentTypeFormURLEncoded = "application/x-www-form-urlencoded" ...

GitHubgolang

Unfortunately, this issue didn't answer what we want.

Someday I read gin(a web framework written in Go) source code, and find the constants for Content-Type!

using

gin.MIMEJSON

and it can get application/json