I want to add a new element after my horizontal listview how can I add it - flutter

Question

This is the projected picture that shows how I am able to add an element.
Below is my code in which I want to add an element so that if my list is not present it also shows the element and if it present then the element is the last element.
I have tried this in some different ways.
Can anyone please help me?
import 'package:flutter/material.dart';
import 'package:cloud_firestore/cloud_firestore.dart';
import 'alllist.dart';
List<Alllist> _alllist = [];
List<Alllist> get alllist => _alllist;
class EduCategory extends StatefulWidget{
final String listcategory;
final int intp;
EduCategory({this.listcategory,this.intp});
#override
EduCategoryState createState() {
return new EduCategoryState();
}
}
class EduCategoryState extends State<EduCategory> {
#override
Widget build(BuildContext context) {
// TODO: implement build
return Container(child: new Column(
crossAxisAlignment: CrossAxisAlignment.stretch,
mainAxisAlignment: MainAxisAlignment.start,
mainAxisSize: MainAxisSize.min,
children: <Widget>[
Row(
mainAxisAlignment: MainAxisAlignment.spaceBetween,
children: <Widget>[
Text(
widget.listcategory,
style: TextStyle(fontWeight: FontWeight.bold),
),
new Row(
children: <Widget>[
new Icon(Icons.play_arrow),
new Text("Watch All", style: TextStyle(fontWeight: FontWeight.bold))
],
)
],
),
Expanded(
child: new Padding(
padding: const EdgeInsets.only(top: 8.0),
child:new StreamBuilder<QuerySnapshot>(
stream: Firestore.instance.collection('all list').where("listcategory",isEqualTo: widget.listcategory).snapshots(),
builder: (BuildContext context,
AsyncSnapshot<QuerySnapshot> snapshot) {
if (!snapshot.hasData) return new Text("no");
if (snapshot.data.documents.length == 0) return InkWell(
child: Stack(
children: <Widget>[
new Container(
width: 80.0,
height: 80.0,
decoration: new BoxDecoration(
shape: BoxShape.rectangle,
border: Border.all(color: Colors.blueGrey),
borderRadius: BorderRadius.circular(5.0),
image: new DecorationImage(
fit: BoxFit.fill,
image: new AssetImage("assets/Plus.png")),
),
margin: const EdgeInsets.symmetric(horizontal: 20.0),
// child: Text(name),
),
Padding(padding: EdgeInsets.only(top: 80.0,left: 20.0),
child: Text("Add Lession",style: TextStyle(fontWeight: FontWeight.bold,color: Colors.blueGrey),),
),
],
),
onTap: (){},
);
return new ListView(
scrollDirection: Axis.horizontal,
children: buildGrid(snapshot.data.documents)
);;
}
),
))
],
),
);
}
List<Widget> buildGrid(List<DocumentSnapshot> documents) {
List<Widget> _gridItems = [];
_alllist.clear();
for (DocumentSnapshot document in documents) {
_alllist.add(Alllist.fromDocument(document));
}
for (Alllist alllist in _alllist) {
_gridItems.add(buildGridItem(alllist));
}
return _gridItems;
}
Widget buildGridItem(Alllist alllist,) {
return widget.intp==0?
InkWell(
child: Stack(
children: <Widget>[
new Container(
width: 80.0,
height: 80.0,
decoration: new BoxDecoration(
shape: BoxShape.circle,
border: Border.all(color: Colors.blue,width: 4.0,style: BorderStyle.solid),
image: new DecorationImage(
fit: BoxFit.fill,
image: new NetworkImage(
alllist.imageUrl)),
),
margin: const EdgeInsets.symmetric(horizontal: 20.0),
// child: Text(name),
),
Padding(padding: EdgeInsets.only(top: 80.0,left: 10.0),
child: Text(alllist.title,style: TextStyle(fontWeight: FontWeight.bold,color: Colors.blueGrey),),
),
],
),
onTap: (){},
):new Row(
children: <Widget>[
InkWell(
child: Stack(
children: <Widget>[
new Container(
width: 80.0,
height: 80.0,
decoration: new BoxDecoration(
shape: BoxShape.rectangle,
borderRadius: BorderRadius.circular(5.0),
image: new DecorationImage(
fit: BoxFit.fill,
image: new NetworkImage(
alllist.imageUrl)),
),
margin: const EdgeInsets.symmetric(horizontal: 20.0),
// child: Text(name),
),
Padding(padding: EdgeInsets.only(top: 80.0,left: 10.0),
child: Text(alllist.title,style: TextStyle(fontWeight: FontWeight.bold,color: Colors.blueGrey),),
),
],
),
onTap: (){},
)
]
);
}
}

Answer 1

You can use the ListView.builder with itemCount as snapshot.data.documents.length + 1.
Code sample:
new StreamBuilder<QuerySnapshot>(
stream: Firestore.instance.collection('all list').where("listcategory",isEqualTo: widget.listcategory).snapshots(),
builder: (BuildContext context,
AsyncSnapshot<QuerySnapshot> snapshot) {
if (!snapshot.hasData) return new Text("no");
var documentsLength = snapshot.data.documents.length;
ListView.builder(itemCount: documentsLength + 1, // +1 for last element
itemBuilder: (context, index) {
if (index == documentsLength) {
//last view which have plus button
} else {
return buildGridItem((Alllist.fromDocument(snapshot.data.documents[index]))
}
});
})

Answer 2

I think that you have to just add condition in itemBuilder checkout in below code;
import 'package:flutter/material.dart';
void main() {
runApp(MyApp());
}
class MyApp extends StatelessWidget {
final List<int> items=[1,2,3,4,5,6];
#override
Widget build(BuildContext context) {
final title = 'Mixed List';
return MaterialApp(
title: title,
home: Scaffold(
appBar: AppBar(
title: Text(title),
),
body: Container(
height: 100.0,
child: ListView.builder(
scrollDirection: Axis.horizontal,
itemCount: items.length + 1 ,
itemBuilder: (context, index) {
if(index < items.length )
{ return Container(
color: Colors.blue,
width: 100.0,
padding: EdgeInsets.all(8.0),
child: new Center(
child: new Text(index.toString()),
),
);
}
else {
return new Container(
color: Colors.blue,
width: 100.0,
child: new Center(
child: new Text(index.toString() + "differnt"),
),
);
}
},
),
),
),
);
}
}