Fix “should not use basic type string as key in context.WithValue” golint

问题

I am passing an uuid in using the Context and WithValue to subsequent functions that handle this *http.request. This uuid is was passed in the authorization header to a REST call to identify a person. The authorization token is verified and needs to accessible to check if the call is itself is authorized.

I used:

ctx := context.WithValue(r.Context(), string("principal_id"), *id)

But golint complains:

should not use basic type string as key in context.WithValue

What is the best option that could be used to retrieve this key that is not a basic type like a simple string?

回答1:

Just use a key type:

type key int

const (
    keyPrincipalID key = iota
    // ...
)

Since you've defined a separate type, it will never collide. Even if you have two packages, pkg1.key(0) != pkg2.key(0).

See also: Go Blog about key collisions in context.

回答2:

Sharing a brief answer for the above question. GitHub Link In short, context.WithValue() needs interface{} type as keys and values.

I hope this helps. Thank you.

来源：https://stackoverflow.com/questions/40891345/fix-should-not-use-basic-type-string-as-key-in-context-withvalue-golint