Question

错误：

错误：未捕获（在承诺中）：错误：StaticInjectorError [AddItemPage]： StaticInjectorError [AddItemPage]： NullInjectorError：没有AddItemPage的提供者！错误：StaticInjectorError [AddItemPage]：StaticInjectorError [AddItemPage]：

NullInjectorError: No provider for AddItemPage!
at _NullInjector.get (http://localhost:8100/build/vendor.js:1276:19)
at resolveToken (http://localhost:8100/build/vendor.js:1564:24)
at tryResolveToken (http://localhost:8100/build/vendor.js:1506:16)
at StaticInjector.get (http://localhost:8100/build/vendor.js:1377:20)
at resolveToken (http://localhost:8100/build/vendor.js:1564:24)
at tryResolveToken (http://localhost:8100/build/vendor.js:1506:16)
at StaticInjector.get (http://localhost:8100/build/vendor.js:1377:20)
at resolveNgModuleDep (http://localhost:8100/build/vendor.js:10938:25)
at NgModuleRef_.get (http://localhost:8100/build/vendor.js:12159:16)
at resolveNgModuleDep (http://localhost:8100/build/vendor.js:10938:25)
at c (http://localhost:8100/build/polyfills.js:3:19752)
at Object.reject (http://localhost:8100/build/polyfills.js:3:19174)
at NavControllerBase._fireError (http://localhost:8100/build/vendor.js:48310:16)
at NavControllerBase._failed (http://localhost:8100/build/vendor.js:48303:14)
at http://localhost:8100/build/vendor.js:48350:59
at t.invoke (http://localhost:8100/build/polyfills.js:3:14976)
at Object.onInvoke (http://localhost:8100/build/vendor.js:4982:33)
at t.invoke (http://localhost:8100/build/polyfills.js:3:14916)
at r.run (http://localhost:8100/build/polyfills.js:3:10143)
at http://localhost:8100/build/polyfills.js:3:20242

当我在HomePage中写道时：

import { AddItemPage } from './../add-item/add-item';
...
constructor(... ,private addItemPage: AddItemPage){...}
...
editItems(item){
    this.addItemPage.editItem(item);
}

所以我想从主页中的 AddItemPage 调用方法。任何解决方案？

Answer 1

将导入添加到 app.module.ts

...
import { AddItemPage } from '../add-item/add-item';

@NgModule({
  declarations: [
    MyApp,
    HomePage,
    AddItemPage 
  ],
...

Answer 2

您正在像提供商一样调用AddItemPage。因此，如果AddItemPage是一个页面，则需要将其导入app.module.ts声明数组。然后，您想从HomePage中的AddItemPage调用方法。要访问组件及其方法，可以使用@ViewChild装饰器。

'use strict';
let app = require('express')();
let http = require('http').Server(app);
let io = require('socket.io')(http);
var Kafka = require('no-kafka');
var bodyParser = require('body-parser');
let techIds = [];

app.use( bodyParser.json() );       // to support JSON-encoded bodies
app.use(bodyParser.urlencoded({     // to support URL-encoded bodies
  extended: true
})); 

app.use(function(req, res, next) {
    res.header("Access-Control-Allow-Origin", "*");
    res.header("Access-Control-Allow-Headers", "Origin, X-Requested-With, Content-Type, Accept");
    next();
  });

app.get('/', function (req, res) {
    res.send("hello.");
});

//Socket IO Method
io.on('connection', (socket) => {

    console.log('USER CONNECTED');

    socket.on('join', function (data) {
        clients.push(
            {
                'socketId': socket.id,
                'mgrId': data.mgrId,
                'techIds': data.attuIds
            });
        //console.log(socket.id + ' ' + data.mgrId + ' USER CONNECTED!!');
    });

    socket.on('disconnect', function (data) {
        if (clients.length > 0) {
            let item = clients.find(x => x.socketId == socket.id);
            const index = clients.indexOf(item);
            if (index > -1) {
                //console.log(clients[index].mgrId + ' USER DISCONNECTED!!');
                clients.splice(index, 1);
                // console.log(clients);
            }
        }
    });

});

http.listen(3007, () => {
  console.log('started on port 3007');
  var consumer = new Kafka.SimpleConsumer({
        connectionString: 'localhost:29092,localhost:29093,localhost:29094',
        clientId: 'no-kafka-client'
    });

    var dataHandler = function (messageSet, topic, partition) {
        messageSet.forEach((m) => {
            console.log(topic, partition, m.offset, m.message.value.toString('utf8'));
            if(topic=="MyMessage")
            {
                const msg = JSON.parse(m.message.value.toString('utf8'));

                if (clients.length > 0) {
                    for (var index = 0; index < clients.length; index++) {
                        var ids = clients[index].techIds;
                        var idx = ids.indexOf(msg.techID.toLowerCase());

                        if (idx > -1) {
                            if (io.sockets.connected[clients[index].socketId]) {
                                io.sockets.connected[clients[index].socketId].emit('message', msg);
                            }
                        }
                    }
                }
            }
        });
    }.bind(this);

    return consumer.init().then(function () {
        var v1= consumer.subscribe('MyMessage', [0, 1], dataHandler);
        var arr=[];
        arr.push([v1]);
        return arr;

    });
});

我不知道目标是什么，但我认为你可以采用不同的方式。希望我能帮忙！

NullInjectorError：没有AddItemPage的提供者！ - 离子3

2 个答案: