Error on Stateful Widget when import Modal class - flutter

Question

The code work fine when I am not importing the modal file.
When I import a modal dart file, the Stateful widget become warning line that make me cant build project.
Below is my modal.dart
class Merchant {
int id;
String type;
String name;
String image;
String address1;
String address2;
String address3;
String city;
String stateCode;
String postcode;
String countryCode;
int priority;
String createdAt;
String updatedAt;
String deletedAt;
String email;
String contact;
String slug;
String emailFinance;
int isEmailFinance;
String legalName;
String legalRegistrationNumber;
String bankSwiftCode;
String bankAccountNumber;
String imageUrl;
String address;
String merchantType;
List<Currencies> currencies;
State state;
Country country;
Merchant(
{this.id,
this.type,
this.name,
this.image,
this.address1,
this.address2,
this.address3,
this.city,
this.stateCode,
this.postcode,
this.countryCode,
this.priority,
this.createdAt,
this.updatedAt,
this.deletedAt,
this.email,
this.contact,
this.slug,
this.emailFinance,
this.isEmailFinance,
this.legalName,
this.legalRegistrationNumber,
this.bankSwiftCode,
this.bankAccountNumber,
this.imageUrl,
this.address,
this.merchantType,
this.currencies,
this.state,
this.country});
Merchant.fromJson(Map<String, dynamic> json) {
id = json['id'];
type = json['type'];
name = json['name'];
image = json['image'];
address1 = json['address1'];
address2 = json['address2'];
address3 = json['address3'];
city = json['city'];
stateCode = json['state_code'];
postcode = json['postcode'];
countryCode = json['country_code'];
priority = json['priority'];
createdAt = json['created_at'];
updatedAt = json['updated_at'];
deletedAt = json['deleted_at'];
email = json['email'];
contact = json['contact'];
slug = json['slug'];
emailFinance = json['email_finance'];
isEmailFinance = json['is_email_finance'];
legalName = json['legal_name'];
legalRegistrationNumber = json['legal_registration_number'];
bankSwiftCode = json['bank_swift_code'];
bankAccountNumber = json['bank_account_number'];
imageUrl = json['image_url'];
address = json['address'];
merchantType = json['merchant_type'];
if (json['currencies'] != null) {
currencies = new List<Currencies>();
json['currencies'].forEach((v) {
currencies.add(new Currencies.fromJson(v));
});
}
state = json['state'] != null ? new State.fromJson(json['state']) : null;
country =
json['country'] != null ? new Country.fromJson(json['country']) : null;
}
Map<String, dynamic> toJson() {
final Map<String, dynamic> data = new Map<String, dynamic>();
data['id'] = this.id;
data['type'] = this.type;
data['name'] = this.name;
data['image'] = this.image;
data['address1'] = this.address1;
data['address2'] = this.address2;
data['address3'] = this.address3;
data['city'] = this.city;
data['state_code'] = this.stateCode;
data['postcode'] = this.postcode;
data['country_code'] = this.countryCode;
data['priority'] = this.priority;
data['created_at'] = this.createdAt;
data['updated_at'] = this.updatedAt;
data['deleted_at'] = this.deletedAt;
data['email'] = this.email;
data['contact'] = this.contact;
data['slug'] = this.slug;
data['email_finance'] = this.emailFinance;
data['is_email_finance'] = this.isEmailFinance;
data['legal_name'] = this.legalName;
data['legal_registration_number'] = this.legalRegistrationNumber;
data['bank_swift_code'] = this.bankSwiftCode;
data['bank_account_number'] = this.bankAccountNumber;
data['image_url'] = this.imageUrl;
data['address'] = this.address;
data['merchant_type'] = this.merchantType;
if (this.currencies != null) {
data['currencies'] = this.currencies.map((v) => v.toJson()).toList();
}
if (this.state != null) {
data['state'] = this.state.toJson();
}
if (this.country != null) {
data['country'] = this.country.toJson();
}
return data;
}
}
class Currencies {
int id;
int merchantId;
String code;
String name;
String createdAt;
String updatedAt;
Null deletedAt;
String balanceCacheType;
Currencies(
{this.id,
this.merchantId,
this.code,
this.name,
this.createdAt,
this.updatedAt,
this.deletedAt,
this.balanceCacheType});
Currencies.fromJson(Map<String, dynamic> json) {
id = json['id'];
merchantId = json['merchant_id'];
code = json['code'];
name = json['name'];
createdAt = json['created_at'];
updatedAt = json['updated_at'];
deletedAt = json['deleted_at'];
balanceCacheType = json['balance_cache_type'];
}
Map<String, dynamic> toJson() {
final Map<String, dynamic> data = new Map<String, dynamic>();
data['id'] = this.id;
data['merchant_id'] = this.merchantId;
data['code'] = this.code;
data['name'] = this.name;
data['created_at'] = this.createdAt;
data['updated_at'] = this.updatedAt;
data['deleted_at'] = this.deletedAt;
data['balance_cache_type'] = this.balanceCacheType;
return data;
}
}
class State {
int id;
String iso;
String iso3;
String name;
String nameAlternate;
String type;
String code;
State(
{this.id,
this.iso,
this.iso3,
this.name,
this.nameAlternate,
this.type,
this.code});
State.fromJson(Map<String, dynamic> json) {
id = json['id'];
iso = json['iso'];
iso3 = json['iso3'];
name = json['name'];
nameAlternate = json['name_alternate'];
type = json['type'];
code = json['code'];
}
Map<String, dynamic> toJson() {
final Map<String, dynamic> data = new Map<String, dynamic>();
data['id'] = this.id;
data['iso'] = this.iso;
data['iso3'] = this.iso3;
data['name'] = this.name;
data['name_alternate'] = this.nameAlternate;
data['type'] = this.type;
data['code'] = this.code;
return data;
}
}
class Country {
int id;
String iso;
String name;
String iso3;
int numcode;
int phonecode;
Country(
{this.id, this.iso, this.name, this.iso3, this.numcode, this.phonecode});
Country.fromJson(Map<String, dynamic> json) {
id = json['id'];
iso = json['iso'];
name = json['name'];
iso3 = json['iso3'];
numcode = json['numcode'];
phonecode = json['phonecode'];
}
Map<String, dynamic> toJson() {
final Map<String, dynamic> data = new Map<String, dynamic>();
data['id'] = this.id;
data['iso'] = this.iso;
data['name'] = this.name;
data['iso3'] = this.iso3;
data['numcode'] = this.numcode;
data['phonecode'] = this.phonecode;
return data;
}
}
I have few modal class. But only this one will gain error when I import it other dart file. I have try to find out the error but couldn't figure it out. Can someone help me to solve this problem? Thank you so much.

Answer 1

I suggest you to separate you class in different file. Put Merchant in a dart file,
Currencies in another dart file and so one.