我正在构建一个带有nodejs的api来与客户端（android）和admin（web）进行交互。
当api启动时，它适用于管理员并且视图正确呈现但是当我将客户端连接到api时，我在服务器控制台中收到错误/警告，如：
App at port 4003
db connection opened successfully
Categroies Count: 2
Error: Can't set headers after they are sent.
at validateHeader (_http_outgoing.js:494:11)
at ServerResponse.setHeader (_http_outgoing.js:501:3)
at ServerResponse.header
(E:\nodeCMSApp\node_modules\express\lib\response.js:767:10)
at ServerResponse.json
(E:\nodeCMSApp\node_modules\express\lib\response.js:264:10)
at Categories.find.select.exec.then.data
(E:\nodeCMSApp\routes\admin_categories.js:20:22)
at <anonymous>
at process._tickCallback (internal/process/next_tick.js:188:7)
(node:13880) UnhandledPromiseRejectionWarning: Unhandled promise
rejection (rejection id: 1): Error: Can't set headers after they are
sent.
(node:13880) [DEP0018] DeprecationWarning: Unhandled promise rejections
are deprecated. In the future, promise rejections that are not handled
will terminate the Node.js process with
a non-zero exit code.
这是我的api代码段：
router.get('/', (req, res) => {
Categories.find({})
.select('title slug image _id')
.exec()
.then(data => {
if (data) {
res.status(200)
.json({
success: true,
count: data.length,
categories: data
})
// I understand that the problem lies here
res.render('admin/all_categories', {
categories: data
});
} else {
res.render('all_categories', {
categories: null
});
}
})
.catch(error => {
console.error(error);
res.send('Error 404');
});
});
我理解这是因为我已经使用响应对象呈现了一个视图，并且我再次调用它来为客户端返回一些json。
我的问题是如何在没有任何错误的情况下同时渲染视图并返回客户端的json数据？ 感谢。