我如何在地图功能中等待 Future ？

Question

My function is below and i put the error screen shot under it. i tried lots of thing but could not find elegant and proper way to achieve this. Thanks for your help.

**It works**

Future<List<UserLike>> getUserLikedPosts() async {
        return userCollection
            .document(_currentUserId)
            .collection(collection_like)
            .limit(POST_LOAD_LIMIT)
            .getDocuments()
            .then(
          (snapshot) {
            if (snapshot == null) return null;
            return snapshot.documents
                .map((userImage) =>
                    UserLike.fromEntity(UserLikeEntity.fromSnapshot(userImage)))
                .toList();
          },
        );
      }



**It does not work**

Future<List<UserLike>> getUserLikedPosts() async {
    return userCollection
        .document(_currentUserId)
        .collection(collection_like)
        .limit(POST_LOAD_LIMIT)
        .getDocuments()
        .then(
      (snapshot) {
        if (snapshot == null) return null;
        return snapshot.documents.map((userImage) async {
          final postEntity =
              UserLike.fromEntity(UserLikeEntity.fromSnapshot(userImage));

          // NEED TO GET DOWNLOAD URL AND UPDATE MY OBJECT
          final downloadUrl = await FirebaseStorage.instance
              .ref()
              .child("user/${post.userId}/post/${post.file}")
              .getDownloadURL();

          return postEntity.copyWith(downloadUrl: downloadUrl);
        }).toList();
      },
    );
  }

Answer 1

I found the solution maybe some one need it.

 Future<List<UserLike>> getUserLikedPosts() async {
    return userCollection
        .document(_currentUserId)
        .collection(collection_like)
        .limit(POST_LOAD_LIMIT)
        .getDocuments()
        .then(
      (snapshot) async {
        if (snapshot == null) return null;
        return await Future.wait(snapshot.documents.map((userImage) async {
          final post = UserLike.fromEntity(UserLikeEntity.fromSnapshot(userImage));
          final url = await _storageRef.child("user/${post.userId}/post/${post.file}").getDownloadURL();
          return post.copyWith(downloadUrl: url);
        }).toList());
      },
    );
  }