proposal: slog: support instance to context value

[lingdor]

Proposal Details

I have some package in my project like: gorm , gin, slog. I don't want dependant on gorm and gin, How can i use traceid linked log content between gorm and gin module?

I want:

package gin

func Request1(){

logger :=slog.With("traceid",123)
ctx:=context.Background()
ctx=slog.NewContext(ctx,logger)
gorm.ReadDB(ctx)
}

package  gorm

func ReadDB(ctx context.Context){
     logger:=slog.DefaultContext(ctx)
    logger.Info("db is ready")
}

so, all modules can write one attribute in one context , and don't need rewrite slog handle.

my code is: golang/exp@master...lingdor:exp:master

thanks

[ianlancetaylor]

CC @jba

[jba]

We considered a function like slog.NewContext when building slog, and actually had it for a while, but it proved too controversial to include (see the last paragraph of that comment). You can easily write your own functions to put a logger in a context and retrieve it; see the documentation for context.Context.Value.

[seankhliao]

Duplicate of #62194

[veqryn]

@lingdor check out https://github.com/veqryn/slog-context