ctxkeys

Under Reviewv0.1.0-alpha

The ctxkeys package defines a custom ContextKey string type to prevent collisions when storing values in Go's context.Context. Using a typed key (instead of a plain string) means two packages that both use the string "user_id" cannot accidentally read each other's values.

Import path: ecom-engine/pkg/ctxkeys

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Type

type ContextKey string

A distinct named type wrapping string. Pass constants of this type as context.WithValue keys.

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Constants

Constant	Value	Set by	Used by
UserIDKey	"user_id"	Auth middleware	Handlers, service layer
UserRoleKey	"user_role"	Auth middleware	Authorization checks
CorrelationIDKey	"correlation_id"	Request middleware	Logging, event publishing

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Usage

Reading from context

import "ecom-engine/pkg/ctxkeys"

func myHandler(ctx context.Context) {
    userID, ok := ctx.Value(ctxkeys.UserIDKey).(string)
    if !ok || userID == "" {
        // not authenticated
    }

    role := ctx.Value(ctxkeys.UserRoleKey).(string)
    corrID := ctx.Value(ctxkeys.CorrelationIDKey).(string)
}

Writing to context (middleware)

ctx = context.WithValue(ctx, ctxkeys.UserIDKey, "usr_018f2fbb-d000-7000-8000-000000000001")
ctx = context.WithValue(ctx, ctxkeys.UserRoleKey, "admin")
ctx = context.WithValue(ctx, ctxkeys.CorrelationIDKey, requestID)

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Why a custom type?

Go's context.WithValue accepts any as the key. If two packages both use the bare string "user_id", they share the same slot and can overwrite each other's values. By defining ContextKey as a separate type, the Go compiler treats ctxkeys.UserIDKey and someotherpkg.UserIDKey (a plain string) as different keys even if their underlying string values are the same.