snapshot.data is NULL flutter - flutter

Question

I'm starter in flutter . I would like to fetch data from Complex json using API . Using postman my response body contain publication object and inside it i have i list of objects. . firstly i created Publication model and i try to use it for fetching data but snapshot.data is still NULL . any help please ??
#override
void initState() {
getproduct(widget.idproduct);
super.initState();
}
Future<Publication> getproduct(int id) async {
var response = await Network().getData('/publication/show/$id');
return Publication.fromJson(json.decode(response.body['publication']));
}
child: SingleChildScrollView(
child: FutureBuilder<Publication>(
future: getproduct(widget.idproduct),
builder: (BuildContext context, AsyncSnapshot snapshot) {
inspect(snapshot.data);
if (snapshot.hasData) {
return Column(
crossAxisAlignment: CrossAxisAlignment.start,
children: <Widget>[
for (int i = 0;
i < snapshot.data.publication.length;
i++)
CommentsList(
comment: snapshot.data.publication[i].comment,
)
],
);
}
and this my Publication Class:
class Publication {
int id;
int userId;
String name;
String description;
String category;
int quantity;
String size;
String brand;
String forWho;
String color;
String delivery;
String price;
int progression;
String discount;
int visibility;
String status;
int softdelete;
String createdAt;
String updatedAt;
String picture1;
String picture2;
String picture3;
Null picture4;
String picture5;
List<Comment> comment;
String ownerpicture;
Publication(
{this.id,
this.userId,
this.name,
this.description,
this.category,
this.quantity,
this.size,
this.brand,
this.forWho,
this.color,
this.delivery,
this.price,
this.progression,
this.discount,
this.visibility,
this.status,
this.softdelete,
this.createdAt,
this.updatedAt,
this.picture1,
this.picture2,
this.picture3,
this.picture4,
this.picture5,
this.comment,
this.ownerpicture});
Publication.fromJson(Map<String, dynamic> json) {
id = json['id'];
userId = json['user_id'];
name = json['name'];
description = json['description'];
category = json['category'];
quantity = json['quantity'];
size = json['size'];
brand = json['brand'];
forWho = json['for_who'];
color = json['color'];
delivery = json['delivery'];
price = json['price'];
progression = json['progression'];
discount = json['discount'];
visibility = json['visibility'];
status = json['status'];
softdelete = json['softdelete'];
createdAt = json['created_at'];
updatedAt = json['updated_at'];
picture1 = json['picture1'];
picture2 = json['picture2'];
picture3 = json['picture3'];
picture4 = json['picture4'];
picture5 = json['picture5'];
if (json['comment'] != null) {
comment = new List<Comment>();
json['comment'].forEach((v) {
comment.add(new Comment.fromJson(v));
});
}
ownerpicture = json['ownerpicture'];
}
Map<String, dynamic> toJson() {
final Map<String, dynamic> data = new Map<String, dynamic>();
data['id'] = this.id;
data['user_id'] = this.userId;
data['name'] = this.name;
data['description'] = this.description;
data['category'] = this.category;
data['quantity'] = this.quantity;
data['size'] = this.size;
data['brand'] = this.brand;
data['for_who'] = this.forWho;
data['color'] = this.color;
data['delivery'] = this.delivery;
data['price'] = this.price;
data['progression'] = this.progression;
data['discount'] = this.discount;
data['visibility'] = this.visibility;
data['status'] = this.status;
data['softdelete'] = this.softdelete;
data['created_at'] = this.createdAt;
data['updated_at'] = this.updatedAt;
data['picture1'] = this.picture1;
data['picture2'] = this.picture2;
data['picture3'] = this.picture3;
data['picture4'] = this.picture4;
data['picture5'] = this.picture5;
if (this.comment != null) {
data['comment'] = this.comment.map((v) => v.toJson()).toList();
}
data['ownerpicture'] = this.ownerpicture;
return data;
}
}
I got the following error when i print (snapshot) :
and i got this error when inspect(snapshot);

Answer 1

It has error, use snapshot.hasError to handle and show the errorMessage,
and error is in your model/Pojo class, something declared as int but it is String. Please check & compare your response and pojo/model.
Check at 60:58 of the PetDetail.dart file
This might help you
https://api.flutter.dev/flutter/widgets/FutureBuilder-class.html#widgets.FutureBuilder.1

Answer 2

in order this line to work
snapshot.data.publication.length;
this line must return an object which must have publication and that must be a list
getproduct(widget.idproduct);