How to use CoinMarketCap API in flutter - api

Question

I'm following a tutorial for an app that displays cryptocurrency prices and I have trouble with the new API. The code below is just from the tutorial and the tutor is using the old coinmarketcap API. Coinmarketcap has migrated to a new one and you need to sign up to get a free API key. Documentation for new API: https://coinmarketcap.com/api/documentation/v1.
I think I need to change _apiURL to https://pro-api.coinmarketcap.com/v1/cryptocurrency/listings/latest?start=1&limit=5000&convert=USD and somehow use the APIKey. Does anyone have a solution? Still kinda new to flutter and API's so i'm sorry if the question is hard to answer.
Future<void> getCryptoPrices() async {
//async to use await, which suspends the current function, while it does other stuff and resumes when data ready
print('getting crypto prices'); //print
String _apiURL =
"https://api.coinmarketcap.com/v1/ticker/"; //url to get data
setState(() {
this._loading = true; //before calling the api, set the loading to true
});
http.Response response = await http.get(_apiURL); //waits for response
setState(() {
this._cryptoList =
jsonDecode(response.body); //sets the state of our widget
this._loading = false; //set the loading to false after we get a response
print(_cryptoList); //prints the list
});
return; }

Answer 1

You can copy paste run full code below and replace your-key before run
You can put API key in headers and parse json response with payloadFromJson and display with FutureBuilder
You can see Payload class definition in full code
Future<Payload> getCryptoPrices() async {
var response = await http.get(
"https://pro-api.coinmarketcap.com/v1/cryptocurrency/listings/latest?start=1&limit=5000&convert=USD",
headers: {
'X-CMC_PRO_API_KEY': 'your-key',
"Accept": "application/json",
});
if (response.statusCode == 200) {
return payloadFromJson(response.body);
}
}
working demo
full code
import 'package:flutter/material.dart';
import 'package:http/http.dart' as http;
import 'dart:convert';
Payload payloadFromJson(String str) => Payload.fromJson(json.decode(str));
String payloadToJson(Payload data) => json.encode(data.toJson());
class Payload {
Payload({
this.status,
this.data,
});
Status status;
List<Datum> data;
factory Payload.fromJson(Map<String, dynamic> json) => Payload(
status: Status.fromJson(json["status"]),
data: List<Datum>.from(json["data"].map((x) => Datum.fromJson(x))),
);
Map<String, dynamic> toJson() => {
"status": status.toJson(),
"data": List<dynamic>.from(data.map((x) => x.toJson())),
};
}
class Datum {
Datum({
this.id,
this.name,
this.symbol,
this.slug,
this.numMarketPairs,
this.dateAdded,
this.tags,
this.maxSupply,
this.circulatingSupply,
this.totalSupply,
this.platform,
this.cmcRank,
this.lastUpdated,
this.quote,
});
int id;
String name;
String symbol;
String slug;
int numMarketPairs;
DateTime dateAdded;
List<Tag> tags;
double maxSupply;
double circulatingSupply;
double totalSupply;
Platform platform;
int cmcRank;
DateTime lastUpdated;
Quote quote;
factory Datum.fromJson(Map<String, dynamic> json) => Datum(
id: json["id"],
name: json["name"],
symbol: json["symbol"],
slug: json["slug"],
numMarketPairs: json["num_market_pairs"],
dateAdded: DateTime.parse(json["date_added"]),
tags: List<Tag>.from(json["tags"].map((x) => tagValues.map[x])),
maxSupply:
json["max_supply"] == null ? null : json["max_supply"].toDouble(),
circulatingSupply: json["circulating_supply"] == null
? null
: json["circulating_supply"].toDouble(),
totalSupply: json["total_supply"] == null
? null
: json["total_supply"].toDouble(),
platform: json["platform"] == null
? null
: Platform.fromJson(json["platform"]),
cmcRank: json["cmc_rank"],
lastUpdated: DateTime.parse(json["last_updated"]),
quote: Quote.fromJson(json["quote"]),
);
Map<String, dynamic> toJson() => {
"id": id,
"name": name,
"symbol": symbol,
"slug": slug,
"num_market_pairs": numMarketPairs,
"date_added": dateAdded.toIso8601String(),
"tags": List<dynamic>.from(tags.map((x) => tagValues.reverse[x])),
"max_supply": maxSupply == null ? null : maxSupply,
"circulating_supply":
circulatingSupply == null ? null : circulatingSupply,
"total_supply": totalSupply == null ? null : totalSupply,
"platform": platform == null ? null : platform.toJson(),
"cmc_rank": cmcRank,
"last_updated": lastUpdated.toIso8601String(),
"quote": quote.toJson(),
};
}
class Platform {
Platform({
this.id,
this.name,
this.symbol,
this.slug,
this.tokenAddress,
});
int id;
Name name;
Symbol symbol;
Slug slug;
String tokenAddress;
factory Platform.fromJson(Map<String, dynamic> json) => Platform(
id: json["id"],
name: nameValues.map[json["name"]],
symbol: symbolValues.map[json["symbol"]],
slug: slugValues.map[json["slug"]],
tokenAddress: json["token_address"],
);
Map<String, dynamic> toJson() => {
"id": id,
"name": nameValues.reverse[name],
"symbol": symbolValues.reverse[symbol],
"slug": slugValues.reverse[slug],
"token_address": tokenAddress,
};
}
enum Name {
ETHEREUM,
TRON,
OMNI,
RSK_SMART_BITCOIN,
BINANCE_COIN,
STELLAR,
NEO,
V_SYSTEMS,
ARDOR,
QTUM,
XRP,
WAVES,
ONTOLOGY,
EOS,
NEBULAS,
NEM,
BIT_SHARES,
BITCOIN_CASH,
INT_CHAIN,
COSMOS,
UBIQ,
VE_CHAIN,
NU_BITS,
PIVX,
COUNTERPARTY,
KOMODO,
ICON,
GX_CHAIN,
VITE,
WANCHAIN,
IOST,
TRUE_CHAIN,
ETHEREUM_CLASSIC
}
final nameValues = EnumValues({
"Ardor": Name.ARDOR,
"Binance Coin": Name.BINANCE_COIN,
"Bitcoin Cash": Name.BITCOIN_CASH,
"BitShares": Name.BIT_SHARES,
"Cosmos": Name.COSMOS,
"Counterparty": Name.COUNTERPARTY,
"EOS": Name.EOS,
"Ethereum": Name.ETHEREUM,
"Ethereum Classic": Name.ETHEREUM_CLASSIC,
"GXChain": Name.GX_CHAIN,
"ICON": Name.ICON,
"INT Chain": Name.INT_CHAIN,
"IOST": Name.IOST,
"Komodo": Name.KOMODO,
"Nebulas": Name.NEBULAS,
"NEM": Name.NEM,
"Neo": Name.NEO,
"NuBits": Name.NU_BITS,
"Omni": Name.OMNI,
"Ontology": Name.ONTOLOGY,
"PIVX": Name.PIVX,
"Qtum": Name.QTUM,
"RSK Smart Bitcoin": Name.RSK_SMART_BITCOIN,
"Stellar": Name.STELLAR,
"TRON": Name.TRON,
"TrueChain": Name.TRUE_CHAIN,
"Ubiq": Name.UBIQ,
"VeChain": Name.VE_CHAIN,
"VITE": Name.VITE,
"v.systems": Name.V_SYSTEMS,
"Wanchain": Name.WANCHAIN,
"Waves": Name.WAVES,
"XRP": Name.XRP
});
enum Slug {
ETHEREUM,
TRON,
OMNI,
RSK_SMART_BITCOIN,
BINANCE_COIN,
STELLAR,
NEO,
V_SYSTEMS,
ARDOR,
QTUM,
XRP,
WAVES,
ONTOLOGY,
EOS,
NEBULAS_TOKEN,
NEM,
BITSHARES,
BITCOIN_CASH,
INT_CHAIN,
COSMOS,
UBIQ,
VECHAIN,
NUBITS,
PIVX,
COUNTERPARTY,
KOMODO,
ICON,
GXCHAIN,
VITE,
WANCHAIN,
IOSTOKEN,
TRUECHAIN,
ETHEREUM_CLASSIC
}
final slugValues = EnumValues({
"ardor": Slug.ARDOR,
"binance-coin": Slug.BINANCE_COIN,
"bitcoin-cash": Slug.BITCOIN_CASH,
"bitshares": Slug.BITSHARES,
"cosmos": Slug.COSMOS,
"counterparty": Slug.COUNTERPARTY,
"eos": Slug.EOS,
"ethereum": Slug.ETHEREUM,
"ethereum-classic": Slug.ETHEREUM_CLASSIC,
"gxchain": Slug.GXCHAIN,
"icon": Slug.ICON,
"int-chain": Slug.INT_CHAIN,
"iostoken": Slug.IOSTOKEN,
"komodo": Slug.KOMODO,
"nebulas-token": Slug.NEBULAS_TOKEN,
"nem": Slug.NEM,
"neo": Slug.NEO,
"nubits": Slug.NUBITS,
"omni": Slug.OMNI,
"ontology": Slug.ONTOLOGY,
"pivx": Slug.PIVX,
"qtum": Slug.QTUM,
"rsk-smart-bitcoin": Slug.RSK_SMART_BITCOIN,
"stellar": Slug.STELLAR,
"tron": Slug.TRON,
"truechain": Slug.TRUECHAIN,
"ubiq": Slug.UBIQ,
"vechain": Slug.VECHAIN,
"vite": Slug.VITE,
"v-systems": Slug.V_SYSTEMS,
"wanchain": Slug.WANCHAIN,
"waves": Slug.WAVES,
"xrp": Slug.XRP
});
enum Symbol {
ETH,
TRX,
OMNI,
RBTC,
BNB,
XLM,
NEO,
VSYS,
ARDR,
QTUM,
XRP,
WAVES,
ONT,
EOS,
NAS,
XEM,
BTS,
BCH,
INT,
ATOM,
UBQ,
VET,
USNBT,
PIVX,
XCP,
KMD,
ICX,
GXC,
VITE,
WAN,
IOST,
TRUE,
ETC
}
final symbolValues = EnumValues({
"ARDR": Symbol.ARDR,
"ATOM": Symbol.ATOM,
"BCH": Symbol.BCH,
"BNB": Symbol.BNB,
"BTS": Symbol.BTS,
"EOS": Symbol.EOS,
"ETC": Symbol.ETC,
"ETH": Symbol.ETH,
"GXC": Symbol.GXC,
"ICX": Symbol.ICX,
"INT": Symbol.INT,
"IOST": Symbol.IOST,
"KMD": Symbol.KMD,
"NAS": Symbol.NAS,
"NEO": Symbol.NEO,
"OMNI": Symbol.OMNI,
"ONT": Symbol.ONT,
"PIVX": Symbol.PIVX,
"QTUM": Symbol.QTUM,
"RBTC": Symbol.RBTC,
"TRUE": Symbol.TRUE,
"TRX": Symbol.TRX,
"UBQ": Symbol.UBQ,
"USNBT": Symbol.USNBT,
"VET": Symbol.VET,
"VITE": Symbol.VITE,
"VSYS": Symbol.VSYS,
"WAN": Symbol.WAN,
"WAVES": Symbol.WAVES,
"XCP": Symbol.XCP,
"XEM": Symbol.XEM,
"XLM": Symbol.XLM,
"XRP": Symbol.XRP
});
class Quote {
Quote({
this.usd,
});
Usd usd;
factory Quote.fromJson(Map<String, dynamic> json) => Quote(
usd: Usd.fromJson(json["USD"]),
);
Map<String, dynamic> toJson() => {
"USD": usd.toJson(),
};
}
class Usd {
Usd({
this.price,
this.volume24H,
this.percentChange1H,
this.percentChange24H,
this.percentChange7D,
this.marketCap,
this.lastUpdated,
});
double price;
double volume24H;
double percentChange1H;
double percentChange24H;
double percentChange7D;
double marketCap;
DateTime lastUpdated;
factory Usd.fromJson(Map<String, dynamic> json) => Usd(
price: json["price"] == null ? null : json["price"].toDouble(),
volume24H:
json["volume_24h"] == null ? null : json["volume_24h"].toDouble(),
percentChange1H: json["percent_change_1h"] == null
? null
: json["percent_change_1h"].toDouble(),
percentChange24H: json["percent_change_24h"] == null
? null
: json["percent_change_24h"].toDouble(),
percentChange7D: json["percent_change_7d"] == null
? null
: json["percent_change_7d"].toDouble(),
marketCap:
json["market_cap"] == null ? null : json["market_cap"].toDouble(),
lastUpdated: DateTime.parse(json["last_updated"]),
);
Map<String, dynamic> toJson() => {
"price": price == null ? null : price,
"volume_24h": volume24H == null ? null : volume24H,
"percent_change_1h": percentChange1H == null ? null : percentChange1H,
"percent_change_24h":
percentChange24H == null ? null : percentChange24H,
"percent_change_7d": percentChange7D == null ? null : percentChange7D,
"market_cap": marketCap == null ? null : marketCap,
"last_updated": lastUpdated.toIso8601String(),
};
}
enum Tag { MINEABLE }
final tagValues = EnumValues({"mineable": Tag.MINEABLE});
class Status {
Status({
this.timestamp,
this.errorCode,
this.errorMessage,
this.elapsed,
this.creditCount,
this.notice,
});
DateTime timestamp;
int errorCode;
dynamic errorMessage;
int elapsed;
int creditCount;
dynamic notice;
factory Status.fromJson(Map<String, dynamic> json) => Status(
timestamp: DateTime.parse(json["timestamp"]),
errorCode: json["error_code"],
errorMessage: json["error_message"],
elapsed: json["elapsed"],
creditCount: json["credit_count"],
notice: json["notice"],
);
Map<String, dynamic> toJson() => {
"timestamp": timestamp.toIso8601String(),
"error_code": errorCode,
"error_message": errorMessage,
"elapsed": elapsed,
"credit_count": creditCount,
"notice": notice,
};
}
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;
}
}
void main() {
runApp(MyApp());
}
class MyApp extends StatelessWidget {
#override
Widget build(BuildContext context) {
return MaterialApp(
title: 'Flutter Demo',
theme: ThemeData(
primarySwatch: Colors.blue,
visualDensity: VisualDensity.adaptivePlatformDensity,
),
home: MyHomePage(title: 'Flutter Demo Home Page'),
);
}
}
class MyHomePage extends StatefulWidget {
MyHomePage({Key key, this.title}) : super(key: key);
final String title;
#override
_MyHomePageState createState() => _MyHomePageState();
}
class _MyHomePageState extends State<MyHomePage> {
int _counter = 0;
Future<Payload> _future;
Future<Payload> getCryptoPrices() async {
var response = await http.get(
"https://pro-api.coinmarketcap.com/v1/cryptocurrency/listings/latest?start=1&limit=5000&convert=USD",
headers: {
'X-CMC_PRO_API_KEY': 'your-key',
"Accept": "application/json",
});
if (response.statusCode == 200) {
return payloadFromJson(response.body);
}
}
#override
void initState() {
// TODO: implement initState
super.initState();
_future = getCryptoPrices();
}
#override
Widget build(BuildContext context) {
return Scaffold(
appBar: AppBar(
title: Text(widget.title),
),
body: FutureBuilder(
future: _future,
builder: (context, AsyncSnapshot<Payload> snapshot) {
switch (snapshot.connectionState) {
case ConnectionState.none:
return Text('none');
case ConnectionState.waiting:
return Center(child: CircularProgressIndicator());
case ConnectionState.active:
return Text('');
case ConnectionState.done:
if (snapshot.hasError) {
return Text(
'${snapshot.error}',
style: TextStyle(color: Colors.red),
);
} else {
return ListView.builder(
itemCount: snapshot.data.data.length,
itemBuilder: (context, index) {
return Card(
elevation: 6.0,
child: Padding(
padding: const EdgeInsets.only(
top: 6.0,
bottom: 6.0,
left: 8.0,
right: 8.0),
child: Row(
crossAxisAlignment: CrossAxisAlignment.start,
children: <Widget>[
Text(snapshot.data.data[index].name),
Spacer(),
Text(snapshot.data.data[index].lastUpdated
.toIso8601String()),
Spacer(),
Text(
snapshot.data.data[index].quote.usd.price
.toString(),
),
],
),
));
});
}
}
}));
}
}