The method 'contains' was called on null. Receiver: null Tried calling: contains("3hm-CodePudding

I would like to add likes to the comments in my application that I wrote, but (The method 'contains' was called on null. Receiver: null Tried calling: contains("3hmly93fmrojxdlz09lh3dzmjqu2")) I'm getting this error. My codes are as follows what I need to do.

Future<void> LikeComment(String postId, String uid, List likes, String commentId) async {
    try {
      if (likes.contains(uid)) {
        await _firestore.collection('posts').doc(postId).collection('comments').doc(commentId).update({
          'likes': FieldValue.arrayRemove([uid]),
        });
      } else {
        await _firestore.collection('posts').doc(postId).collection('comments').doc(commentId).update({
          'likes': FieldValue.arrayUnion([uid]),
        });
      }
    } catch (e) {
      print(
        e.toString(),
      );
    }
  }

Row(
              children: [
                LikeAnimation(
                  isAnimating: widget.snap['likes'].contains(myUid),
                  smallLike: true,
                  child: IconButton(
                    onPressed: () async {
                      await FirestoreMethods().LikeComment(
                        myUid,
                        widget.snap['postId'],
                        widget.snap['commentId'],
                        widget.snap['likes'],
                      );
                    },
                    icon: widget.snap['likes'].contains(myUid)
                        ? const Icon(
                      Icons.favorite,
                      color: Colors.red,
                    )
                        : const Icon(
                      Icons.favorite_border,
                    ),
                  ),
                ),

              ]),

CodePudding user response：

It is possible to get null from reading snap, try

 widget.snap['likes']?? [],

and

 isAnimating: widget.snap['likes']!=null && widget.snap['likes'].contains(myUid), 
 icon: widget.snap['likes']!=null && widget.snap['likes'].contains(myUid)

Also it is better to null check on others variable