USDA FoodData Central API Get Food Nutrients in your Flutter App.

Friends, today in this article we will teach you how you can use the USDA Food Data Central API in your flutter app. In this app, we will have a food list And we want to get the nutrients of each food from the API. We will receive data in JSON format. To use that data we have to convert that JSON to model data class then show them on the details screen.

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http: ^0.13.5

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flutter_lints:

This is our file: main.dart

import 'package:flutter/material.dart';

import 'homeScreen.dart';

void main() {
  runApp(MyApp());
}

class MyApp extends StatelessWidget {
  @override
  Widget build(BuildContext context) {
    return MaterialApp(
      debugShowCheckedModeBanner: false,
      theme: ThemeData(
        primarySwatch: Colors.blue,
      ),
      home: MyHomePage(),
    );
  }
}

class MyHomePage extends StatefulWidget {
  @override
  _MyHomePageState createState() => _MyHomePageState();
}

class _MyHomePageState extends State<MyHomePage> {
  @override
  Widget build(BuildContext context) {

    return HomeScreen();
  }
}

Here is our first Screen UI file: homeScreen.dart

import 'package:flutter/material.dart';
import '/foodlist.dart';

import 'detailScreen.dart';

class HomeScreen extends StatefulWidget {
  const HomeScreen({Key? key}) : super(key: key);

  @override
  _HomeScreenState createState() => _HomeScreenState();
}

class _HomeScreenState extends State<HomeScreen> {
  var foodList = FoodList(
    name: '',
    foodCategory: '',
    id: 0,
  );
  List<FoodList> _foodList = [];
  @override
  void initState() {
    _foodList = foodList.foodList();
    super.initState();
  }

  @override
  Widget build(BuildContext context) {
    return Scaffold(
      appBar: AppBar(
        title: const Text(
          "Food Nutrients",
          style: TextStyle(fontSize: 28),
        ),
      ),
      body: ListView.builder(
          itemCount: _foodList.length,
          itemBuilder: (context, index) {
            return InkWell(
              onTap: () {
                Navigator.push(
                  context,
                  MaterialPageRoute(
                      builder: (context) => DetailScreen(_foodList[index].id)),
                );
              },
              child: Padding(
                padding: const EdgeInsets.all(8.0),
                child: Column(
                  mainAxisAlignment: MainAxisAlignment.start,
                  crossAxisAlignment: CrossAxisAlignment.start,
                  children: [
                    Text(
                      "${_foodList[index].name}",
                      style: TextStyle(
                          fontSize: 20,
                          fontWeight: FontWeight.w600,
                          color: Colors.black54),
                    ),
                    Text(
                      "${_foodList[index].foodCategory}",
                      style: TextStyle(fontSize: 16, color: Colors.black38),
                    ),
                  ],
                ),
              ),
            );
          }),
    );
  }
}

Here is the foodlist.dart file

class FoodList {
  final int id;
  final String name;
  final String foodCategory;

  FoodList({
    required this.id,
    required this.name,
    required this.foodCategory,
  });

  List<FoodList> foodList() {
    return [
      FoodList(
        id: 1102670,
        name: 'Mango',
        foodCategory: 'Fruit',
      ),
      FoodList(
        id: 1102879,
        name: 'Potato',
        foodCategory: 'vegetable',
      ),
      FoodList(
        id: 1103528,
        name: 'Okra',
        foodCategory: 'vegetable',
      ),
      FoodList(
        id: 1102653,
        name: 'Banana',
        foodCategory: 'Fruit',
      ),
      FoodList(
        id: 1102597,
        name: 'Orange',
        foodCategory: 'Fruit',
      ),
      FoodList(
        id: 1100534,
        name: 'Peanut',
        foodCategory: 'Nuts',
      ),
      FoodList(
        id: 1102702,
        name: 'Blueberries',
        foodCategory: 'Fruit',
      ),
      FoodList(
        id: 1102644,
        name: 'Apple',
        foodCategory: 'Fruit',
      )
    ];
  }
}

This is our model class: foodmodel.dart

// To parse this JSON data, do
//
//     final foodData = foodDataFromMap(jsonString);

import 'dart:convert';

FoodData foodDataFromMap(String str) => FoodData.fromMap(json.decode(str));

String foodDataToMap(FoodData data) => json.encode(data.toMap());

class FoodData {
  FoodData({
    this.wweiaFoodCategory,
    this.description,
    this.foodAttributes,
    this.foodCode,
    this.inputFoods,
    this.startDate,
    this.endDate,
    this.foodComponents,
    this.foodClass,
    this.fdcId,
    this.publicationDate,
    this.foodNutrients,
    this.foodPortions,
    this.dataType,
  });

  WweiaFoodCategory? wweiaFoodCategory;
  String? description;
  List<FoodAttribute>? foodAttributes;
  String? foodCode;
  List<InputFood>? inputFoods;
  String? startDate;
  String? endDate;
  List<dynamic>? foodComponents;
  String? foodClass;
  String? fdcId;
  String? publicationDate;
  List<FoodNutrient>? foodNutrients;
  List<FoodPortion>? foodPortions;
  String? dataType;

  FoodData copyWith({
    WweiaFoodCategory? wweiaFoodCategory,
    String? description,
    List<FoodAttribute>? foodAttributes,
    String? foodCode,
    List<InputFood>? inputFoods,
    String? startDate,
    String? endDate,
    List<dynamic>? foodComponents,
    String? foodClass,
    String? fdcId,
    String? publicationDate,
    List<FoodNutrient>? foodNutrients,
    List<FoodPortion>? foodPortions,
    String? dataType,
  }) =>
      FoodData(
        wweiaFoodCategory: wweiaFoodCategory ?? this.wweiaFoodCategory,
        description: description ?? this.description,
        foodAttributes: foodAttributes ?? this.foodAttributes,
        foodCode: foodCode ?? this.foodCode,
        inputFoods: inputFoods ?? this.inputFoods,
        startDate: startDate ?? this.startDate,
        endDate: endDate ?? this.endDate,
        foodComponents: foodComponents ?? this.foodComponents,
        foodClass: foodClass ?? this.foodClass,
        fdcId: fdcId ?? this.fdcId,
        publicationDate: publicationDate ?? this.publicationDate,
        foodNutrients: foodNutrients ?? this.foodNutrients,
        foodPortions: foodPortions ?? this.foodPortions,
        dataType: dataType ?? this.dataType,
      );

  factory FoodData.fromMap(Map<String, dynamic> json) => FoodData(
    wweiaFoodCategory: WweiaFoodCategory.fromMap(json["wweiaFoodCategory"]),
    description: json["description"],
    foodAttributes: List<FoodAttribute>.from(json["foodAttributes"].map((x) => FoodAttribute.fromMap(x))),
    foodCode: json["foodCode"],
    inputFoods: List<InputFood>.from(json["inputFoods"].map((x) => InputFood.fromMap(x))),
    startDate: json["startDate"],
    endDate: json["endDate"],
    foodComponents: List<dynamic>.from(json["foodComponents"].map((x) => x)),
    foodClass: json["foodClass"],
    fdcId: json["fdcId"].toString(),
    publicationDate: json["publicationDate"],
    foodNutrients: List<FoodNutrient>.from(json["foodNutrients"].map((x) => FoodNutrient.fromMap(x))),
    foodPortions: List<FoodPortion>.from(json["foodPortions"].map((x) => FoodPortion.fromMap(x))),
    dataType: json["dataType"],
  );

  Map<String, dynamic> toMap() => {
    "wweiaFoodCategory": wweiaFoodCategory!.toMap(),
    "description": description,
    "foodAttributes": List<dynamic>.from(foodAttributes!.map((x) => x.toMap())),
    "foodCode": foodCode,
    "inputFoods": List<dynamic>.from(inputFoods!.map((x) => x.toMap())),
    "startDate": startDate,
    "endDate": endDate,
    "foodComponents": List<dynamic>.from(foodComponents!.map((x) => x)),
    "foodClass": foodClass,
    "fdcId": fdcId,
    "publicationDate": publicationDate,
    "foodNutrients": List<dynamic>.from(foodNutrients!.map((x) => x.toMap())),
    "foodPortions": List<dynamic>.from(foodPortions!.map((x) => x.toMap())),
    "dataType": dataType,
  };
}

class FoodAttribute {
  FoodAttribute({
    this.id,
    this.value,
    this.name,
    this.foodAttributeType,
  });

  int? id;
  String? value;
  String? name;
  FoodAttributeType? foodAttributeType;

  FoodAttribute copyWith({
    int? id,
    String? value,
    String? name,
    FoodAttributeType? foodAttributeType,
  }) =>
      FoodAttribute(
        id: id ?? this.id,
        value: value ?? this.value,
        name: name ?? this.name,
        foodAttributeType: foodAttributeType ?? this.foodAttributeType,
      );

  factory FoodAttribute.fromMap(Map<String, dynamic> json) => FoodAttribute(
    id: json["id"],
    value: json["value"],
    name: json["name"],
    foodAttributeType: FoodAttributeType.fromMap(json["foodAttributeType"]),
  );

  Map<String, dynamic> toMap() => {
    "id": id,
    "value": value,
    "name": name,
    "foodAttributeType": foodAttributeType!.toMap(),
  };
}

class FoodAttributeType {
  FoodAttributeType({
    this.id,
    this.name,
    this.description,
  });

  int? id;
  String? name;
  String? description;

  FoodAttributeType copyWith({
    int? id,
    String? name,
    String? description,
  }) =>
      FoodAttributeType(
        id: id ?? this.id,
        name: name ?? this.name,
        description: description ?? this.description,
      );

  factory FoodAttributeType.fromMap(Map<String, dynamic> json) => FoodAttributeType(
    id: json["id"],
    name: json["name"],
    description: json["description"],
  );

  Map<String, dynamic> toMap() => {
    "id": id,
    "name": name,
    "description": description,
  };
}

class FoodNutrient {
  FoodNutrient({
    this.nutrient,
    this.type,
    this.id,
    this.amount,
  });

  Nutrient? nutrient;
  Type? type;
  int? id;
  double? amount;

  FoodNutrient copyWith({
    Nutrient? nutrient,
    Type? type,
    int? id,
    double? amount,
  }) =>
      FoodNutrient(
        nutrient: nutrient ?? this.nutrient,
        type: type ?? this.type,
        id: id ?? this.id,
        amount: amount ?? this.amount,
      );

  factory FoodNutrient.fromMap(Map<String, dynamic> json) => FoodNutrient(
    nutrient: Nutrient.fromMap(json["nutrient"]),
    type: typeValues.map[json["type"]],
    id: json["id"] == null ? null : json["id"],
    amount: json["amount"] == null ? null : json["amount"].toDouble(),
  );

  Map<String, dynamic> toMap() => {
    "nutrient": nutrient!.toMap(),
    "type": typeValues.reverse![type!],
    "id": id == null ? null : id,
    "amount": amount == null ? null : amount,
  };
}

class Nutrient {
  Nutrient({
    this.id,
    this.number,
    this.name,
    this.rank,
    this.unitName,
  });

  int? id;
  String? number;
  String? name;
  String? rank;
  String? unitName;

  Nutrient copyWith({
    int? id,
    String? number,
    String? name,
    String? rank,
    UnitName? unitName,
  }) =>
      Nutrient(
        id: id ?? this.id,
        number: number ?? this.number,
        name: name ?? this.name,
        rank: rank ?? this.rank,
        unitName: unitName as String? ?? this.unitName,
      );

  factory Nutrient.fromMap(Map<String, dynamic> json) => Nutrient(
    id: json["id"],
    number: json["number"],
    name: json["name"],
    rank: json["rank"].toString(),
    unitName: json["unitName"],
  );

  Map<String, dynamic> toMap() => {
    "id": id,
    "number": number,
    "name": name,
    "rank": rank,
    "unitName": unitNameValues.reverse![unitName as UnitName],
  };
}

enum UnitName { G, KCAL, MG, UNIT_NAME_G }

final unitNameValues = EnumValues({
  "g": UnitName.G,
  "kcal": UnitName.KCAL,
  "mg": UnitName.MG,
  "µg": UnitName.UNIT_NAME_G
});

enum Type { FOOD_NUTRIENT }

final typeValues = EnumValues({
  "FoodNutrient": Type.FOOD_NUTRIENT
});

class FoodPortion {
  FoodPortion({
    this.id,
    this.portionDescription,
    this.gramWeight,
    this.sequenceNumber,
    this.modifier,
    this.measureUnit,
  });

  int? id;
  String? portionDescription;
  String? gramWeight;
  String? sequenceNumber;
  String? modifier;
  MeasureUnit? measureUnit;

  FoodPortion copyWith({
    int? id,
    String? portionDescription,
    String? gramWeight,
    String? sequenceNumber,
    String? modifier,
    MeasureUnit? measureUnit,
  }) =>
      FoodPortion(
        id: id ?? this.id,
        portionDescription: portionDescription ?? this.portionDescription,
        gramWeight: gramWeight ?? this.gramWeight,
        sequenceNumber: sequenceNumber ?? this.sequenceNumber,
        modifier: modifier ?? this.modifier,
        measureUnit: measureUnit ?? this.measureUnit,
      );

  factory FoodPortion.fromMap(Map<String, dynamic> json) => FoodPortion(
    id: json["id"],
    portionDescription: json["portionDescription"],
    gramWeight: json["gramWeight"].toString(),
    sequenceNumber: json["sequenceNumber"].toString(),
    modifier: json["modifier"],
    measureUnit: MeasureUnit.fromMap(json["measureUnit"]),
  );

  Map<String, dynamic> toMap() => {
    "id": id,
    "portionDescription": portionDescription,
    "gramWeight": gramWeight,
    "sequenceNumber": sequenceNumber,
    "modifier": modifier,
    "measureUnit": measureUnit!.toMap(),
  };
}

class MeasureUnit {
  MeasureUnit({
    this.id,
    this.name,
    this.abbreviation,
  });

  int? id;
  String? name;
  String? abbreviation;

  MeasureUnit copyWith({
    int? id,
    String? name,
    String? abbreviation,
  }) =>
      MeasureUnit(
        id: id ?? this.id,
        name: name ?? this.name,
        abbreviation: abbreviation ?? this.abbreviation,
      );

  factory MeasureUnit.fromMap(Map<String, dynamic> json) => MeasureUnit(
    id: json["id"],
    name: json["name"],
    abbreviation: json["abbreviation"],
  );

  Map<String, dynamic> toMap() => {
    "id": id,
    "name": name,
    "abbreviation": abbreviation,
  };
}

class InputFood {
  InputFood({
    this.id,
    this.foodDescription,
    this.ingredientDescription,
    this.ingredientWeight,
    this.portionCode,
    this.portionDescription,
    this.sequenceNumber,
    this.ingredientCode,
    this.unit,
    this.amount,
  });

  int? id;
  String? foodDescription;
  String? ingredientDescription;
  String? ingredientWeight;
  String? portionCode;
  String? portionDescription;
  String? sequenceNumber;
  String? ingredientCode;
  String? unit;
  String? amount;

  InputFood copyWith({
    int? id,
    String? foodDescription,
    String? ingredientDescription,
    String? ingredientWeight,
    String? portionCode,
    String? portionDescription,
    String? sequenceNumber,
    String? ingredientCode,
    String? unit,
    String? amount,
  }) =>
      InputFood(
        id: id ?? this.id,
        foodDescription: foodDescription ?? this.foodDescription,
        ingredientDescription: ingredientDescription ?? this.ingredientDescription,
        ingredientWeight: ingredientWeight ?? this.ingredientWeight,
        portionCode: portionCode ?? this.portionCode,
        portionDescription: portionDescription ?? this.portionDescription,
        sequenceNumber: sequenceNumber ?? this.sequenceNumber,
        ingredientCode: ingredientCode ?? this.ingredientCode,
        unit: unit ?? this.unit,
        amount: amount ?? this.amount,
      );

  factory InputFood.fromMap(Map<String, dynamic> json) => InputFood(
    id: json["id"],
    foodDescription: json["foodDescription"],
    ingredientDescription: json["ingredientDescription"],
    ingredientWeight: json["ingredientWeight"].toString(),
    portionCode: json["portionCode"],
    portionDescription: json["portionDescription"],
    sequenceNumber: json["sequenceNumber"].toString(),
    ingredientCode: json["ingredientCode"].toString(),
    unit: json["unit"],
    amount: json["amount"].toString(),
  );

  Map<String, dynamic> toMap() => {
    "id": id,
    "foodDescription": foodDescription,
    "ingredientDescription": ingredientDescription,
    "ingredientWeight": ingredientWeight,
    "portionCode": portionCode,
    "portionDescription": portionDescription,
    "sequenceNumber": sequenceNumber,
    "ingredientCode": ingredientCode,
    "unit": unit,
    "amount": amount,
  };
}

class WweiaFoodCategory {
  WweiaFoodCategory({
    this.wweiaFoodCategoryCode,
    this.wweiaFoodCategoryDescription,
  });

  int? wweiaFoodCategoryCode;
  String? wweiaFoodCategoryDescription;

  WweiaFoodCategory copyWith({
    int? wweiaFoodCategoryCode,
    String? wweiaFoodCategoryDescription,
  }) =>
      WweiaFoodCategory(
        wweiaFoodCategoryCode: wweiaFoodCategoryCode ?? this.wweiaFoodCategoryCode,
        wweiaFoodCategoryDescription: wweiaFoodCategoryDescription ?? this.wweiaFoodCategoryDescription,
      );

  factory WweiaFoodCategory.fromMap(Map<String, dynamic> json) => WweiaFoodCategory(
    wweiaFoodCategoryCode: json["wweiaFoodCategoryCode"],
    wweiaFoodCategoryDescription: json["wweiaFoodCategoryDescription"],
  );

  Map<String, dynamic> toMap() => {
    "wweiaFoodCategoryCode": wweiaFoodCategoryCode,
    "wweiaFoodCategoryDescription": wweiaFoodCategoryDescription,
  };
}

class EnumValues<T> {
  Map<String, T> map;
  Map<T, String>? reverseMap;

  EnumValues(this.map);

  Map<T, String>? get reverse {
    if (reverseMap == null) {
      reverseMap = map.map((k, v) => new MapEntry(v, k));
    }
    return reverseMap;
  }
}

This is our detailScreen.dart file

import 'package:flutter/cupertino.dart';
import 'package:flutter/material.dart';
import 'models/foodmodel.dart';
import 'package:http/http.dart' as http;
import 'dart:convert' as convert;

class DetailScreen extends StatefulWidget {
  final int id;
  DetailScreen(this.id);
  @override
  _DetailScreenState createState() => _DetailScreenState();
}

class _DetailScreenState extends State<DetailScreen> {
  late FoodData foodData;
  bool loading = true;
  @override
  void initState() {
    fetchData();
    super.initState();
  }

  Future<void> fetchData() async {
    var url = Uri.parse(
        "https://api.nal.usda.gov/fdc/v1/food/${widget.id}?api_key=[Please add here your API key without square brackets ]");
    var response = await http.get(url);
    if (response.statusCode == 200) {
      var decodedResponse = convert.jsonDecode(response.body);
      print('===================$decodedResponse');
      foodData = FoodData.fromMap(decodedResponse);
      print('===================$foodData');
      setState(() {
        loading = false;
      });
    } else {
      throw Exception('Failed to load data');
    }
  }

  @override
  Widget build(BuildContext context) {
    return Scaffold(
      appBar: AppBar(
        title: loading
            ? SizedBox.shrink()
            : FittedBox(
                child: Text(
                  "${foodData.description}",
                  style: TextStyle(fontSize: 28),
                ),
              ),
      ),
      body: Container(
        child: loading
            ? Center(child: CircularProgressIndicator())
            : Column(
                children: [
                  Text(
                    "Portion: per 100g",
                    style: TextStyle(fontSize: 25),
                  ),
                  Container(
                    child: Expanded(
                      child: ListView.builder(
                          itemCount: foodData == null
                              ? 0
                              : foodData.foodNutrients!.length,
                          itemBuilder: (context, index) {
                            var nutrient =
                                foodData.foodNutrients![index].nutrient!;
                            return Column(
                              mainAxisAlignment: MainAxisAlignment.center,
                              crossAxisAlignment: CrossAxisAlignment.start,
                              children: [
                                Padding(
                                  padding: const EdgeInsets.all(8.0),
                                  child: FittedBox(
                                    alignment: Alignment.topLeft,
                                    fit: BoxFit.scaleDown,
                                    child: Text(
                                      foodData.foodNutrients![index].amount ==
                                              null
                                          ? " ${nutrient.name}: "
                                          : "${nutrient.name}:   ${foodData.foodNutrients![index].amount} ${foodData.foodNutrients![index].amount == null ? "" : nutrient.unitName}",
                                      style: foodData.foodNutrients![index]
                                                  .amount ==
                                              null
                                          ? TextStyle(
                                              backgroundColor: Colors.green,
                                              fontWeight: FontWeight.w600,
                                              fontSize: 23,
                                            )
                                          : TextStyle(
                                              fontSize: 20,
                                              fontWeight: FontWeight.w600,
                                            ),
                                    ),
                                  ),
                                ),
                                Container(
                                  height: 1,
                                  color: Colors.black54,
                                ),
                              ],
                            );
                          }),
                    ),
                  )
                ],
              ),
      ),
    );
  }
}

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USDA FoodData Central API Get Food Nutrients in your Flutter App.

USDA FoodData Central API Get Food Nutrients in your Flutter App.(updated 8/13/2022)

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