middleware/prefix: Add Prefix API to get the global key prefix

Author: AlexisMontagne

middleware/logger/middleware.go

@@ -65,10 +65,6 @@ type DB struct {
 }
 
 func (db *DB) Unwrap() redis.DB {
-	if u, ok := db.db.(interface{ Unwrap() redis.DB }); ok {
-		return u.Unwrap()
-	}
-
 	return db.db
 }
 

middleware/prefix/db.go

@@ -3,6 +3,8 @@ package prefix
 import (
 	"context"
 	"fmt"
+	"maps"
+	"slices"
 	"strings"
 
 	"github.com/upfluence/redis"
@@ -40,6 +42,20 @@ func (f *factory) Wrap(next redis.DB) redis.DB {
 		return next
 	}
 
+	if pnext, ok := next.(*db); ok {
+		vs := maps.Clone(pnext.vs)
+
+		for k, v := range f.vs {
+			vs[k] = v
+		}
+
+		return &db{
+			next:   pnext.next,
+			prefix: pnext.prefix + f.prefix,
+			vs:     vs,
+		}
+	}
+
 	return &db{next: next, prefix: f.prefix, vs: f.vs}
 }
 
@@ -49,7 +65,9 @@ type db struct {
 	vs     map[string]Executor
 }
 
-func (db *db) Close() error { return db.next.Close() }
+func (db *db) Prefix() string   { return db.prefix }
+func (db *db) Unwrap() redis.DB { return db.next }
+func (db *db) Close() error     { return db.next.Close() }
 
 func (db *db) Do(ctx context.Context, cmd string, vs ...interface{}) redis.Scanner {
 	e, ok := db.vs[cmd]
@@ -62,3 +80,23 @@ func (db *db) Do(ctx context.Context, cmd string, vs ...interface{}) redis.Scann
 
 	return e.Execute(ctx, db.next, db.prefix, cmd, vs)
 }
+
+func Prefix(db redis.DB) string {
+	var prefixes []string
+
+	for {
+		if pdb, ok := db.(interface{ Prefix() string }); ok {
+			prefixes = append(prefixes, pdb.Prefix())
+		}
+
+		udb, ok := db.(interface{ Unwrap() redis.DB })
+
+		if !ok {
+			slices.Reverse(prefixes)
+
+			return strings.Join(prefixes, "")
+		}
+
+		db = udb.Unwrap()
+	}
+}

middleware/prefix/executor_test.go

@@ -58,6 +58,20 @@ func TestIntegration(t *testing.T) {
 		err = db.Do(ctx, "KEYS", "*").Scan(&keys)
 		require.NoError(t, err)
 		assert.Equal(t, []string{"buz"}, keys)
+
+		for _, tt := range []struct {
+			db   redis.DB
+			want string
+		}{
+			{db: db, want: ""},
+			{db: prefixedDB, want: "foobar:"},
+			{
+				db:   prefix.NewFactory("buz").Wrap(prefixedDB),
+				want: "foobar:buz:",
+			},
+		} {
+			assert.Equal(t, tt.want, prefix.Prefix(tt.db))
+		}
 	})
 
 }