api - 我如何返回未来在带有 Provider 的 ListView 中？

Question

我正在尝试使用 Provider 包将 Future 放入列表视图，但没有成功。谁能给我一些建议或链接来解释如何在返回双精度的 Future 上实现 notifylisteners() ？

这是 getPrice() 的未来：

import 'dart:collection';
import 'package:http/http.dart' as http;
import 'package:flutter/material.dart';
import 'package:stock_watchlist/stock_service.dart';

class StockData extends ChangeNotifier {
  List<Stock> _stocks = [
    Stock(symbol: 'AAPL'),
    Stock(symbol: 'AMD'),
    Stock(symbol: 'TSLA')
  ];

  UnmodifiableListView<Stock> get stocks {
    return UnmodifiableListView(_stocks);
  }

  int get stockCount {
    return _stocks.length;
  }

  void addStock(String symbol, double price, double eps) {
    final stock = Stock(symbol: symbol);
    _stocks.add(stock);
    notifyListeners();
  }

  void deleteStock(Stock stock) {
    _stocks.remove(stock);
    notifyListeners();
  }

  Future<double> getPrice(String symbol) async {
    String url =
        "https://sandbox.iexapis.com/stable/stock/$symbol/quote/latestPrice?token=Tsk_38ddda0b877a4510b42a37ae713cdc96";

    http.Response response = await http.get(url);
    double price = double.tryParse(response.body);
    return price;
  }

  Future<double> getEps(String symbol) async {
    String url =
        "https://sandbox.iexapis.com/stable/stock/$symbol/stats/ttmEPS?token=Tsk_38ddda0b877a4510b42a37ae713cdc96";

    http.Response response = await http.get(url);
    double eps = double.tryParse(response.body);
    return eps;
  }
}

这是我试图将 getPrice() 的值输入到文本小部件的地方，但它给了我“'Future' 的实例而不是值。

我还不能嵌入图片

import 'package:flutter/material.dart';
import 'package:provider/provider.dart';
import 'package:stock_watchlist/constants.dart';
import 'package:stock_watchlist/stock_model.dart';

class StockList extends StatelessWidget {
  @override
  Widget build(BuildContext context) {
    return Consumer<StockData>(
      builder: (context, stockData, child) {
        return ListView.builder(
          itemCount: stockData.stockCount,
          itemBuilder: (context, index) {
            //
            final stockIndex = stockData.stocks[index];
            //
            return ListTile(
              title: Text(
                stockIndex.symbol,
                style: TextStyle(
                  color: kTextColor,
                ),
              ),
              subtitle: Text(
                stockIndex.price.toString(),
                style: TextStyle(
                  color: kTextColor,
                ),
              ),
            );
          },
        );
      },
    );
  }
}

标签： apiflutterdartfutureprovider

Answer 1

谢谢，我想我用 FutureBuilder 想通了。这是我使用的代码。

class StockList extends StatelessWidget {
  @override
  Widget build(BuildContext context) {
    return Consumer<StockData>(
      builder: (context, stockData, child) {
        return ListView.builder(
          itemCount: stockData.stockCount,
          itemBuilder: (context, index) {
            //
            final stockIndex = stockData.stocks[index];
            //
            return ListTile(
              title: Text(
                stockIndex.symbol,
                style: TextStyle(
                  color: kTextColor,
                ),
              ),
              subtitle: FutureBuilder(
                future: stockData.getPrice(stockIndex.symbol),
                builder: (context, snapshot) => Text(
                  snapshot.data.toString(),
                  style: TextStyle(
                    color: kTextColor,
                  ),
                ),
              ),
            );
          },
        );
      },
    );
  }
}