Debug School

rakesh kumar
rakesh kumar

Posted on • Updated on

Flutter Error and Debugging tips

Error1

type 'Null' is not a subtype of type 'String'
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my existing code is

import 'dart:convert';


class SearchInfluencer {
int id;
String userId;
String userName;
String userEmail;
String filePic;
String slugId;
String slug;
String slugname;
String countryId;
String stateId;
String cityId;
String mobile;
String digitalMarketer;
String bio;
String socialSite;
String socialPrice;
String socialCurrency;
String adminId;
String cartId;
String influencerAdminId;
String cartSocials;
String currency;
String influencerEmail;

SearchInfluencer({
this.id = 0,
required this.userId,
required this.userName,
required this.userEmail,
required this.filePic,
required this.slugId,
required this.slug,
required this.slugname,
required this.countryId,
required this.stateId,
required this.cityId,
required this.mobile,
required this.digitalMarketer,
required this.bio,
required this.socialSite,
required this.socialPrice,
required this.socialCurrency,
required this.adminId,
required this.cartId,
required this.influencerAdminId,
required this.cartSocials,
required this.currency,
required this.influencerEmail,
});

factory SearchInfluencer.fromJson(Map<String, dynamic> map) {
return SearchInfluencer(
id: map["id"],
userId: map["user_id"],
userName: map["user_name"],
userEmail: map["user_email"],
filePic: map["file_pic"],
slugId: map["slug_id"],
slug: map["slug"],
slugname: map["slugname"],
countryId: map["country_id"],
stateId: map["state_id"],
cityId: map["city_id"],
mobile: map["mobile"],
digitalMarketer: map["digital_marketer"],
bio: map["bio"],
socialSite: map["social_site"],
socialPrice: map["social_price"],
socialCurrency: map["social_currency"],
adminId: map["admin_id"],
cartId: map["cart_id"],
influencerAdminId: map["influencer_admin_id"],
cartSocials: map["cart_socials"],
currency: map["currency"],
influencerEmail: map["influencer_email"],
);
}

Map<String, dynamic> toJson() {
return {
"id": id,
"user_id": userId,
"user_name": userName,
"user_email": userEmail,
"file_pic": filePic,
"slug_id": slugId,
"slug": slug,
"slugname": slugname,
"country_id": countryId,
"state_id": stateId,
"city_id": cityId,
"mobile": mobile,
"digital_marketer": digitalMarketer,
"bio": bio,
"social_site": socialSite,
"social_price": socialPrice,
"social_currency": socialCurrency,
"admin_id": adminId,
"cart_id": cartId,
"influencer_admin_id": influencerAdminId,
"cart_socials": cartSocials,
"currency": currency,
"influencer_email": influencerEmail,
};
}

@override
String toString() {
return 'SearchInfluencer{id: $id, userId: $userId, userName: $userName, userEmail: $userEmail, filePic: $filePic, slugId: $slugId, slug: $slug, slugname: $slugname, countryId: $countryId, stateId: $stateId, cityId: $cityId, mobile: $mobile, digitalMarketer: $digitalMarketer, bio: $bio, socialSite: $socialSite, socialPrice: $socialPrice, socialCurrency: $socialCurrency, adminId: $adminId, cartId: $cartId, influencerAdminId: $influencerAdminId, cartSocials: $cartSocials, currency: $currency, influencerEmail: $influencerEmail}';
}

bool startsWith(String query) {
// return userName.toLowerCase().contains(query.toLowerCase());
return userName?.toLowerCase().contains(query.toLowerCase()) ?? false;

}
}

List<SearchInfluencer> searchInfluencerFromJson(String jsonData) {
final data = json.decode(jsonData);
return List<SearchInfluencer>.from(data.map((item) => SearchInfluencer.fromJson(item)));
}

String searchInfluencerToJson(SearchInfluencer data) {
final jsonData = data.toJson();
return json.encode(jsonData);
}
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Solution 

 String? userId;
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  bool startsWith(String query) {
    return userName?.toLowerCase().contains(query.toLowerCase()) ?? false;
  }
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import 'dart:convert';

class SearchInfluencer {
  int id;
  String? userId;
  String? userName;
  String? userEmail;
  String? filePic;
  String? slugId;
  String? slug;
  String? slugname;
  String? countryId;
  String? stateId;
  String? cityId;
  String? mobile;
  String? digitalMarketer;
  String? bio;
  String? socialSite;
  String? socialPrice;
  String? socialCurrency;
  String? adminId;
  String? cartId;
  String? influencerAdminId;
  String? cartSocials;
  String? currency;
  String? influencerEmail;

  SearchInfluencer({
    this.id = 0,
    this.userId,
    this.userName,
    this.userEmail,
    this.filePic,
    this.slugId,
    this.slug,
    this.slugname,
    this.countryId,
    this.stateId,
    this.cityId,
    this.mobile,
    this.digitalMarketer,
    this.bio,
    this.socialSite,
    this.socialPrice,
    this.socialCurrency,
    this.adminId,
    this.cartId,
    this.influencerAdminId,
    this.cartSocials,
    this.currency,
    this.influencerEmail,
  });

  factory SearchInfluencer.fromJson(Map<String, dynamic> map) {
    return SearchInfluencer(
      id: map["id"] ?? 0,
      userId: map["user_id"],
      userName: map["user_name"],
      userEmail: map["user_email"],
      filePic: map["file_pic"],
      slugId: map["slug_id"],
      slug: map["slug"],
      slugname: map["slugname"],
      countryId: map["country_id"],
      stateId: map["state_id"],
      cityId: map["city_id"],
      mobile: map["mobile"],
      digitalMarketer: map["digital_marketer"],
      bio: map["bio"],
      socialSite: map["social_site"],
      socialPrice: map["social_price"],
      socialCurrency: map["social_currency"],
      adminId: map["admin_id"],
      cartId: map["cart_id"],
      influencerAdminId: map["influencer_admin_id"],
      cartSocials: map["cart_socials"],
      currency: map["currency"],
      influencerEmail: map["influencer_email"],
    );
  }

  Map<String, dynamic> toJson() {
    return {
      "id": id,
      "user_id": userId,
      "user_name": userName,
      "user_email": userEmail,
      "file_pic": filePic,
      "slug_id": slugId,
      "slug": slug,
      "slugname": slugname,
      "country_id": countryId,
      "state_id": stateId,
      "city_id": cityId,
      "mobile": mobile,
      "digital_marketer": digitalMarketer,
      "bio": bio,
      "social_site": socialSite,
      "social_price": socialPrice,
      "social_currency": socialCurrency,
      "admin_id": adminId,
      "cart_id": cartId,
      "influencer_admin_id": influencerAdminId,
      "cart_socials": cartSocials,
      "currency": currency,
      "influencer_email": influencerEmail,
    };
  }

  @override
  String toString() {
    return 'SearchInfluencer{id: $id, userId: $userId, userName: $userName, userEmail: $userEmail, filePic: $filePic, slugId: $slugId, slug: $slug, slugname: $slugname, countryId: $countryId, stateId: $stateId, cityId: $cityId, mobile: $mobile, digitalMarketer: $digitalMarketer, bio: $bio, socialSite: $socialSite, socialPrice: $socialPrice, socialCurrency: $socialCurrency, adminId: $adminId, cartId: $cartId, influencerAdminId: $influencerAdminId, cartSocials: $cartSocials, currency: $currency, influencerEmail: $influencerEmail}';
  }

  bool startsWith(String query) {
    return userName?.toLowerCase().contains(query.toLowerCase()) ?? false;
  }
}

List<SearchInfluencer> searchInfluencerFromJson(String jsonData) {
  final data = json.decode(jsonData);
  return List<SearchInfluencer>.from(data.map((item) => SearchInfluencer.fromJson(item)));
}

String searchInfluencerToJson(SearchInfluencer data) {
  final jsonData = data.toJson();
  return json.encode(jsonData);
}
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Error2:The argument type 'String' can't be assigned to the parameter type 'int'.

final selectedCity = countryViewModel.cities.firstWhere(
                          (city) => city.city_name == newValue,
                          orElse: () => City(city_id: 'All', city_name: 'All', state_id: 0, country_id: 'All'),
                        );
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Solution

city_id: 0
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 setState(() {
                        final selectedCity = countryViewModel.cities.firstWhere(
                          (city) => city.city_name == newValue,
                          orElse: () => City(city_id: 0, city_name: 'All', state_id: 0, country_id: 'All'),
                        );
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Error3:

 type 'Null' is not a subtype of type 'int'
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  factory States.fromJson(Map<String, dynamic> map) {
    return States(
      id: map["id"] ?? 0,
      state_id: map["state_id"] ?? 0,
      state_name: map["state_name"] ?? '',
      country_id: map["country_id"] ?? '',
    );
  }
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full code solution

import 'dart:convert';

class States {
  int id;
  int state_id;
  String state_name;
  String country_id;

  States({
    this.id = 0,
    required this.state_id,
    required this.state_name,
    required this.country_id,
  });

  factory States.fromJson(Map<String, dynamic> map) {
    return States(
      id: map["id"] ?? 0,
      state_id: map["state_id"] ?? 0,
      state_name: map["state_name"] ?? '',
      country_id: map["country_id"] ?? '',
    );
  }

  Map<String, dynamic> toJson() {
    return {
      "id": id,
      "state_id": state_id,
      "state_name": state_name,
      "country_id": country_id,
    };
  }

  @override
  String toString() {
    return 'States{id: $id, state_id: $state_id, state_name: $state_name, country_id: $country_id}';
  }
}

List<States> stateFromJson(String jsonData) {
  final data = json.decode(jsonData);
  return List<States>.from(data.map((item) => States.fromJson(item)));
}

String stateToJson(States data) {
  final jsonData = data.toJson();
  return json.encode(jsonData);
}
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error4:

type 'int' is not a subtype of type 'String'
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country_id: map["country_id"].toString(), // Convert to String
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 factory States.fromJson(Map<String, dynamic> map) {
    return States(
      id: map["id"] ?? 0,
      state_id: map["state_id"] ?? 0,
      state_name: map["state_name"] ?? '',
      country_id: map["country_id"].toString(), // Convert to String
    );
  }
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Debug

Debugging while calling api

void fetchInfluencers() {
  // Fetch data from an API or a local source
  // For example purposes, let's use a static list
  final response = await fetchInfluencersFromApi();
  print(response); // Log the response to see the raw data
  influencers = response.map((data) => SearchInfluencer.fromJson(data)).toList();
}
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 countries = await api.getcountry();
      print("Fetched countries:");
       print("Fetched countries: ${countries.map((c) => c.country_name).toList()}");
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Debugging while calling provider

  final influencerViewModel = Provider.of<InfluencerViewModel>(context);
    final countryViewModel = Provider.of<CountryViewModel>(context);
    final tagViewModel = Provider.of<TagViewModel>(context);
   print("Selected country: $_selectedCountry");
    print("Available countries: ${countryViewModel.countries.map((c) => c.country_name).toList()}");
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Errors:null check operator used on null value

Image description

my existing code is

 final isInCart = cartSocials!.contains(entry.key); // Check if the social site is in cartSocials
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Solution

 final isInCart = cartSocials?.contains(entry.key) ??false; // Check if the social site is in cartSocials
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