[英]Nodejs stream (Error: Can't set headers after they are sent)
我正在嘗試從Braintree服務器構建一個api。 參考此文檔https://developers.braintreepayments.com/javascript+node/reference/general/result-handling/search-results
要從其服務器訪問所有事務,我必須返回一個節點流。
前
app.get('/project', function(req, res) {
if(req.user) {
var stream = gateway.transaction.search(function (search) {
search.customerId().is(req.user.id);
});
stream.on("ready", function () {
console.log(stream.searchResponse);
});
stream.on("data", function (data) {
res.json(data) // can't set headers after they are sent.
});
}
});
我了解流會分塊返回數據,因此上面的res.json()
很可能多次被調用,從而導致Error: Can't set headers after they are sent
。
所以我的問題是如何將數據一整塊發送給客戶端? nodejs流使我感到困惑,我將閱讀更多有關它的內容,但是了解如何在不重新發送標頭的情況下將數據發送到客戶端將是很棒的。
除非正在讀取的流處於對象模式,否則您不應對data
事件做出任何假設。 因為TCP是流,所以您可能會發生一個data
事件或一個data
事件(取決於輸入的大小)(一百)。
您可能想要的是這樣的東西(假設stream
不在對象模式下):
app.get('/project', function(req, res) {
if(req.user) {
var stream = gateway.transaction.search(function (search) {
search.customerId().is(req.user.id);
});
stream.on("ready", function () {
console.log(stream.searchResponse);
});
var buf = '';
stream.on("data", function (data) {
buf += data;
});
stream.on("end", function() {
res.setHeader('Content-Type', 'application/json');
res.send(buf);
});
}
});
或者只是將流通過管道傳遞給響應:
app.get('/project', function(req, res) {
if(req.user) {
var stream = gateway.transaction.search(function (search) {
search.customerId().is(req.user.id);
});
stream.on("ready", function () {
console.log(stream.searchResponse);
});
res.setHeader('Content-Type', 'application/json');
stream.pipe(res);
}
});
對於對象流,您可以執行以下操作:
app.get('/project', function(req, res) {
if(req.user) {
var stream = gateway.transaction.search(function (search) {
search.customerId().is(req.user.id);
});
stream.on("ready", function () {
console.log(stream.searchResponse);
});
var result = [];
stream.on("data", function (data) {
result.push(data);
});
stream.on("end", function() {
res.json(result);
});
}
});
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