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I have a list that stores items that I don't want to display as part of my StreamBuilder, ListView. This list retrieves its information from a firebase rtdb.

I use a StreamBuilder to populate the ListView, and then I use a for-loop to try and iterate through the list that contains items I don't want to display. So far I can get the ListView populated, but the items removed from the StreamBuilder aren't accurate.

Below is how I have approached it (Any help is much appreciated):

I can confirm that the list definitely contains the info I don't want displayed

ListView.builder(
    physics: BouncingScrollPhysics(),
    itemCount: friends.length,
    itemBuilder: (context, index) {
      final friend = friends[index];

      if (friend.userID == uid){
        return null;
      } else {

        for (FriendSuggestionModel hidden in hiddenSuggestions){
          if (hidden.userID == friend.userID){
            return null;
          } else {
            return friendThumbnail(index, friend);
          }
        }
        return null;
      }
    });
Frank van Puffelen
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callMe_whatever
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1 Answers1

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First, I believe you need to return a Widget in itemBuilder, so don't use return null instead you can return an empty container with return Container().

You also could use list.contains(x) method to verify if this id should be hide (as I imagine , as follows:

itemBuilder: (context, index) {
      final friend = friends[index];

      if (friend.userID == uid){
        return const Container();
      } else {
        return hiddenSuggestions.map((hidden) => hidden.userID).toList().contains(friend.userID)
          ? const Container()
          : friendThumbnail(index, friend);
      }
    }

Check that method docs here: https://api.dart.dev/stable/2.0.0/dart-core/Iterable/contains.html

Leonardo Ugiete
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    Thank you for the response @Leonardo! There were minor issues with syntax, but I have fixed them and it's working as expected - shall I edit your response and mark it as accepted? – callMe_whatever Feb 04 '22 at 18:50
  • I couldn't edit the above comment, but it is correct! I just removed the return statements after the "?" and "!". Also, the line with the mapping should be: `return hiddenSuggestions.map((hidden) => hidden.userID).toList().contains(friend.userID)` – callMe_whatever Feb 06 '22 at 02:31
  • I edited to help anyone with the same doubt, thanks. I think this should be the accepted response – Leonardo Ugiete Feb 07 '22 at 11:41