Flutter ListView按下时导致重复值

Question

我有两种类型的类型过滤，以获取帖子列表，然后传递到详细信息页面。我创建了新列表来获取帖子。

// I believed this is the reason of the error, when it back it loop again.
list<Post> cat1 = [];   
list<Post> cat2 = [];

........

Widget _postList ( List<Post> posts ) {
  for ( var item in posts) {
    if (widget.cat1postsids.contains(item.id)) {
      cat1.add(item);
  }}
  return Container(
    child: _fetchPostbyCat1( cat1 )
  );
}

Widget _fetchPostbyCat1 ( List<Post> posts ) {
  for ( var item in posts) {
    if (widget.cat2postsids.contains(item.id)) {
      cat2.add(item);
  }}
  return Container(
    child: _getPost( cat2 )
  );
}

Widget _getPost ( List<Post> posts ) {
  return ListView.builder .... 
}

我可以完美显示帖子列表，并推送到帖子详细信息页面。但是，当我从“帖子详细信息”页面按回时，该帖子条目是重复的。

下面是我的导航员传递的帖子ID

Navigator.push(context, MaterialPageRoute(
  builder: (context) => PostDetails(postID)));

和后面的Onpress按钮。

onPressed: () {
  Navigator.pop(context, true);
  return Future.value(true);
}

实现它的最佳方法是什么？谢谢。 下面是帖子的ListView。

class PostListView extends StatefulWidget {

   final List selectedIDS;
   final String name;
   PostListView(this.selectedIDS,  this.name);

   @override
   PostListViewState createState() => new PostListViewState();

}

class PostListViewState extends State<PostListView> {

   PostApi postapi;
   List <Post> getPostByCat1 = [];
   List <Post> getPostByCat2 = [];

   @override
   void initState() {
      super.initState();
      postapi = PostApi();
   }

   @override
   Widget build(BuildContext context) {

      return Scaffold(
      appBar: AppBar(
      title: Text('Post'),
      leading: new IconButton(
         icon: new Icon(Icons.arrow_back),
         onPressed: () { Navigator.pop(context, true); })),

      body: NestedScrollView(
        headerSliverBuilder: (BuildContext context, bool innerBoxIsScrolled) {
        return [ SliverList(
           delegate: SliverChildListDelegate([
              Container(
                 child: Padding(
                    padding: EdgeInsets.only(left: 20.0, top: 30.0, right: 20.0, bottom: 30.0 ),
                    child: Column(
                    mainAxisSize: MainAxisSize.max,
                    crossAxisAlignment: CrossAxisAlignment.stretch,
                    children: <Widget>[
                       AutoSizeText( 'LATEST POST', maxLines: 2,
                       textAlign: TextAlign.center,
                       style: TextStyle (fontSize: 28, color: Colors.black, fontWeight: FontWeight.w700))
                    ])),
                    decoration: new BoxDecoration(
                        border: Border(
                          bottom: BorderSide(width: 1.0, color: Colors.grey ))))]))];},
        body: SafeArea(
            child: SizedBox(
                child: Column(
                  mainAxisAlignment: MainAxisAlignment.spaceEvenly,
                  mainAxisSize: MainAxisSize.min,
                  crossAxisAlignment: CrossAxisAlignment.start,
                  children: <Widget>[
                    Expanded(
                        child: ListView (
                            children: <Widget>[
                              Container(
                                  child: FutureBuilder(
                                    future: postapi.fetchAllPost(),
                                    builder: (BuildContext context, AsyncSnapshot snapshot) {

                                      if( snapshot.connectionState == ConnectionState.done ) {
                                        if( snapshot.hasError ) {
                                          return returnerror( snapshot.error.toString());
                                        }
                                      }
                                      if( snapshot.hasData) {
                                        return _postList( snapshot.data );
                                      }
                                      return Center ( child: CircularProgressIndicator());

                                    }))]))])))));
}

Widget _postList ( List<Post> posts ) {
   for ( var item in posts) {
     if (widget.name.contains(item.catname)) {
       getPostByCat1.add(item);
   }}
   return Container( child: _getPosts(getPostByCat1));
}

Widget _getPosts (List<Post> posts) {
  for(var item in getPostByCat1){
    if(widget.selectedIDS.contains(item.post_id))  {
      getPostByCat2.add(item);
    }
  } return Container(child: _listPosts(getPostByCat2));
}

Widget _listPosts (List<Post> posts) {
  return ListView.builder(
  physics: ClampingScrollPhysics(),
  shrinkWrap: true,
  itemCount: posts.length,
  itemBuilder: ( BuildContext context, int index ) {

  var imgUrl = ApiUtil.MAIN_API_URL + ApiUtil.IMAGE_PATH  + posts[index].image;

  String postID = posts[index].id;
  String postname = posts[index].name;

  return new Card (
     child: InkWell(
        onTap: () {
           Navigator.push(context, MaterialPageRoute(
              builder: (context) => PostDetails(postID, postname)));},
            child: Padding(
              padding: const EdgeInsets.all(10.0),
              child: new Row(
                  crossAxisAlignment: CrossAxisAlignment.start,
                  children: <Widget>[

                    Expanded(
                      flex: 1,
                      child: Image.network(imgUrl),
                    ),

                    Expanded(
                      flex: 3,
                      child: Padding(
                          padding: EdgeInsets.all(10.0),
                          child: ListTile(
                            title: new Text(posts[index].name,
                              style: TextStyle(
                                  fontSize: 22,
                                  fontWeight: FontWeight.w700
                              ),
                            ),
                            subtitle: new Text(posts[index].subname,
                              style: TextStyle(
                                fontSize: 16,

  )))))])))); });}
 }