add shorturl example code

example/shorturl/rpc/transform/internal/logic/expandlogic.go

@@ -0,0 +1,35 @@
+package logic
+
+import (
+	"context"
+
+	"shorturl/rpc/transform/internal/svc"
+	transform "shorturl/rpc/transform/pb"
+
+	"github.com/tal-tech/go-zero/core/logx"
+)
+
+type ExpandLogic struct {
+	ctx    context.Context
+	svcCtx *svc.ServiceContext
+	logx.Logger
+}
+
+func NewExpandLogic(ctx context.Context, svcCtx *svc.ServiceContext) *ExpandLogic {
+	return &ExpandLogic{
+		ctx:    ctx,
+		svcCtx: svcCtx,
+		Logger: logx.WithContext(ctx),
+	}
+}
+
+func (l *ExpandLogic) Expand(in *transform.ExpandReq) (*transform.ExpandResp, error) {
+	res, err := l.svcCtx.Model.FindOne(in.Shorten)
+	if err != nil {
+		return nil, err
+	}
+
+	return &transform.ExpandResp{
+		Url: res.Url,
+	}, nil
+}