Question

每次尝试将ObservableArray绑定到ListView时，我都会有一个NativeScript应用程序崩溃。

当我注释掉我的standings.js文件的第9行时，登录功能运行，并且积分加载功能运行，但当我取消注释该行时整个应用程序崩溃，登录功能甚至不运行

这是standings.js：

var dialogsModule = require("ui/dialogs");
var Observable = require("data/observable").Observable;
var ObservableArray = require("data/observable-array").ObservableArray;
var StandingsListViewModel = require("../../shared/view-models/standings-list-view-model");
var page;

var standingsList = new StandingsListViewModel([]);
var pageData = new Observable({
    standingsList: standingsList
});

exports.loaded = function(args) {
    page = args.object;
    page.bindingContext = pageData;

    standingsList.load();
};

standings.xml：

<Page loaded="loaded">
<GridLayout rows="auto, *" columns="2*, *">
    <Label id="header" text="Standings" colSpan="2" horizontalAlignment="center"/>

    <ListView items="{{ standingsList }}" id="standingsList" row="1" colSpan="2">
        <ListView.itemTemplate>
            <Label text="{{ place }}" horizontalAlignment="left" verticalAlignment="center"/>
            <Label text="{{ username }}" col="2" horizontalAlignment="left" verticalAlignment="center"/>
        </ListView.itemTemplate>
    </ListView>
</GridLayout>
</Page>

and standings-list-view-model.js：

var config = require("../../shared/config");
var fetchModule = require("fetch");
var ObservableArray = require("data/observable-array").ObservableArray;

function StandingsListViewModel(items) {
var viewModel = new ObservableArray(items);

viewModel.load = function() {
    console.log("hit");
    var url = config.apiURI + "getStandings.cfm?weekid=397";
    return fetch(url)
    .then(handleErrors)
    .then(function(data) {
        var parsedData = JSON.parse(data._bodyInit);
        var users = parsedData.users;
        users.forEach(function(standing) {
            viewModel.push({
                place: standing.place,
                username: standing.username
            });
        });
        console.log(viewModel._array[0].username);
    })
    .catch(function(error) {
        console.log("ERROR: " + error);
    });
};

return viewModel;

}

function handleErrors(response) {
    if (!response.ok) {
        console.log(JSON.stringify(response));
        throw Error(response.statusText);
    }
    return response;
}

module.exports = StandingsListViewModel;

非常感谢有关如何更好地调试的任何帮助或想法。

Answer 1

我认为问题出在var standingsList = new StandingsListViewModel([]);。使用new将创建变量类型的对象。但是在这里你将StandingListViewModel()定义为一个函数，而不是一个可能没有像你期望的那样返回standingList的类。将该行替换为：

var standingsList = StandingsListViewModel([]);

NativeScript App数据绑定崩溃

1 个答案: