Flutter 和 Firebase 实时数据库，如何显示发帖用户的姓名

我正在使用 flutter 和 Firebase Realtime 创建一个应用程序，其中我具有用户可以发布文章的功能。 我想要列出所有这些文章以及发布它的用户的名称。 但是如何显示他的名字，知道在数据库级别它只是记录发布帖子的人的 ID？ 谢谢

以下是相关数据库的结构：

我使用 Firebase Realtime 请求的代码：

ref = FirebaseDatabase.instance.reference().child("post").orderByKey();
FirebaseAnimatedList(
  scrollDirection: Axis.vertical,
  shrinkWrap: true,
  query: ref,
  itemBuilder: (BuildContext context, DataSnapshot snapshot,
      Animation<double> animation, int index) {
    return Container(
      padding: EdgeInsets.all(10),
      margin: EdgeInsets.only(bottom: 20),
      child: Column(
        crossAxisAlignment: CrossAxisAlignment.start,
        children: <Widget>[
          Row(
            mainAxisAlignment: MainAxisAlignment.spaceBetween,
            children: <Widget>[
              Row(
                children: <Widget>[
                  Container(
                    width: 50,
                    height: 50,
                    decoration: BoxDecoration(
                        shape: BoxShape.circle,
                        image: DecorationImage(
                            image: NetworkImage(snapshot
                                .value["imagePost"]
                                .toString()),
                            fit: BoxFit.cover)),
                  ),
                  SizedBox(
                    width: 10,
                  ),
                  Column(
                    crossAxisAlignment: CrossAxisAlignment.start,
                    children: <Widget>[
                      RichText(
                        text: TextSpan(
                          //text: snapshot.value["user_id"].toString(),
                          text: "" +
                              FirebaseDatabase.instance
                                  .reference()
                                  .child('users')
                                  .child(
                                      "${snapshot.value["user_id"].toString()}")
                                  .child('nom')
                                  .toString(),
                          style: TextStyle(
                              color: Colors.grey[900],
                              fontSize: 14,
                              fontWeight: FontWeight.bold,
                              letterSpacing: 1),
                        ),
                      ),
                      SizedBox(
                        height: 3,
                      ),
                      Text(
                        "${timeago.format(DateTime.parse("${DateTime.fromMillisecondsSinceEpoch(snapshot.value['createAt'])}"), locale: 'fr_short')}",
                        style: TextStyle(
                            fontSize: 12, color: Colors.grey),
                      ),
                    ],
                  )
                ],
              ),
            ],
          ),
          SizedBox(
            height: 20,
          ),
          RichText(
            text: TextSpan(
              text: snapshot.value["description"].toString(),
              style: TextStyle(
                  fontSize: 12,
                  color: Colors.grey[800],
                  height: 1.5,
                  letterSpacing: .7),
            ),
          ),
          SizedBox(
            height: 20,
          ),
          snapshot.value["imagePost"].toString() != ''
              ? Container(
                  height: 200,
                  decoration: BoxDecoration(
                    borderRadius: BorderRadius.circular(10),
                    image: DecorationImage(
                        image: NetworkImage(
                            snapshot.value["imagePost"].toString()),
                        fit: BoxFit.cover),
                  ),
                )
              : Container(
                  height: 200,
                  decoration: BoxDecoration(
                    borderRadius: BorderRadius.circular(10),
                    color: kPrimaryColor,
                  ),
                ),
          SizedBox(
            height: 20,
          ),
          Row(
            mainAxisAlignment: MainAxisAlignment.spaceBetween,
            children: <Widget>[
              makeLikeButton(isActive: false),
              Padding(
                padding: EdgeInsets.only(
                  right: 10,
                ),
              ),
              Row(
                children: <Widget>[
                  makeLike(),
                  SizedBox(
                    width: 5,
                  ),
                  Text(
                    "2.5K",
                    style: TextStyle(
                        fontSize: 10, color: Colors.grey[800]),
                  )
                ],
              ),
            ],
          ),
        ],
      ),
    );
  },
),