服务器发送事件`EventSource.onmessage`未激发

Question

我正在尝试使用以下服务器发送事件的示例。看起来服务器正在发送数据，但事件没有启动，事件流中也没有记录任何数据(通过开发人员工具(。

角码(服务(：

getAlertsEvent(fieldIds: Guid[]): Observable<responseModel.LoanAlert> {
return new Observable(obs => {
fieldIds.forEach(fieldId => {
const source = new EventSource(`http://localhost:3000/loan/alerts/${fieldId}`);
alert('Succesfully creates the EventSource, I see reuslt 200 in Networking tab but with 0 events');
source.onmessage = (ev): void => {
this.zone.run(() => {
alert('This alert will not happen');
obs.next(ev.data);
});
};
source.onerror = (err): void => this.zone.run(() => obs.error(err));
// Also tried this way with no luck:
// source.addEventListener('message', (event) => {
//   obs.next(event.data);
// });
});
});
}

组件：

this.loansService.getAlertsEvent(this.fields.map(field => field.fieldId)).subscribe(alert => {
console.log(alert);
});

Node.js代码：

const express = require('express');
const parser = require('body-parser');
const app = express();
const EventEmitter = require('events');
const Stream = new EventEmitter();
app.unsubscribe(parser.json());
app.use(
parser.urlencoded({
extended: true,
})
);
app.get('/loan/alerts/:fieldId', function(req, res) {
res.writeHead(200, {
'Content-Type': 'text/event-stream',
'Cache-Control': 'no-cache',
'Access-Control-Allow-Origin': "*",
Conection: 'keep-alive'
});
Stream.on(req.params.fieldId, function(event, data) {
res.write(JSON.stringify(data));
});
});
setInterval(function() {
const item = {
formId: 51415,
alertId: 'asdfasdfasdf',
messageStatus: 'NEW',
messageType: 'ACTION_MESSAGE_FROM_SERVER',
actionType: 'NAVIGATION',
message: 'New Message!',
archiverId: '12345',
documentCode: 3,
from: 'Internal Server Message',
messageTimestamp: new Date().toJSON(),
markedAsRead: false,
};
Stream.emit('aed29580-09fd-e411-b8e1-e61f13cf5d4b', 'message', item);
}, 5000);
app.listen(3000);
console.log('Express E2e Mock server is running');

当手动转到http://localhost:3000/loan/alerts/aed29580-09fd-e411-b8e1-e61f13cf5d4b我看到打印到屏幕上的消息，所以我想这可能是一个Angular或丢失的安全标头。谢谢

Answer 1

我刚刚意识到，多亏了这个答案，事件必须以特定的方式格式化。我相应地更改了res.write的值：

Stream.on(req.params.fieldId, function(event, data) {
res.write('event: ' + String(event) + 'n' + 'data: ' + JSON.stringify(data) + 'nn');
});