如何在koa发送HTTP响应之前等待url回调?
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我有一个koa
路由器,我需要调用一个api,其中异步返回结果。这意味着我无法立即得到我的结果,当它没问题时,api会调用我的callback url
。但现在我必须像使用sync api一样使用它,这意味着我必须等到调用回调url。
我的路由器是这样的:
router.post("/voice", async (ctx, next) => {
// call a API here
const params = {
data: "xxx",
callback_url: "http//myhost/ret_callback",
};
const req = new Request("http://xxx/api", {
method: "POST",
body: JSON.stringify(params),
});
const resp = await fetch(req);
const data = await resp.json();
// data here is not the result I want, this api just return a task id, this api will call my url back
const taskid = data.taskid;
// now I want to wait here until I got "ret_callback"
// .... wait .... wait
// "ret_callback" is called now
// get the answer in "ret_callback"
ctx.body = {
result: "ret_callback result here",
}
})
我的回调网址是这样的:
router.post("/ret_callback", async (ctx, next) => {
const params = ctx.request.body;
// taskid will tell me this answer to which question
const taskid = params.taskid;
// this is exactly what I want
const result = params.text;
ctx.body = {
code: 0,
message: "success",
};
})
那么我怎么能让这个aync
api表现得像sync
api?
答案
function getMovieTitles(substr) {
let movies = [];
let fdata = (page, search, totalPage) => {
let mpath = {
host: "jsonmock.hackerrank.com",
path: "/api/movies/search/?Title=" + search + "&page=" + page,
};
let raw = '';
https.get(mpath, (res) => {
res.on("data", (chunk) => {
raw += chunk;
});
res.on("end", () => {
tdata = JSON.parse(raw);
t = tdata;
totalPage(t);
});
});
}
fdata(1, substr, (t) => {
i = 1;
mdata = [];
for (i = 1; i <= parseInt(t.total_pages); i++) {
fdata(i, substr, (t) => {
t.data.forEach((v, index, arrs) => {
movies.push(v.Title);
if (index === arrs.length - 1) {
movies.sort();
if (parseInt(t.page) === parseInt(t.total_pages)) {
movies.forEach(v => {
console.log(v)
})
}
}
});
});
}
});
}
getMovieTitles("tom")
另一答案
好吧首先,这不应该是你的“目标”。 NodeJS works better as ASync。
但是,让我们假设您仍然需要它出于某种原因,所以看看sync-request package on npm(那里有一个巨大的注释,你不应该在生产中。
但是,我希望你的意思是如何使这个API更简单(如在一个调用有点东西)。你仍然需要.next
或await
,但无论如何它将是一个电话。
如果是这种情况,请评论这个答案我可以写一个我自己使用的方法。
另一答案
这个怎么样 ?
router.post("/voice", async (ctx, next) => {
const params = {
data: "xxx",
callback_url: "http//myhost/ret_callback",
};
const req = new Request("http://xxx/api", {
method: "POST",
body: JSON.stringify(params),
});
const resp = await fetch(req);
const data = await resp.json();
// data here is not the result I want, this api just return a task id, this api will call my url back
const taskid = data.taskid;
let response = null;
try{
response = await new Promise((resolve,reject)=>{
//call your ret_callback and when it finish call resolve(with response) and if it fails, just reject(with error);
});
}catch(err){
//errors
}
// get the answer in "ret_callback"
ctx.body = {
result: "ret_callback result here",
}
});
另一答案
只需将resolve()传递给另一个函数即可。例如,您可以这样做:
// use a map to save a lot of resolve()
const taskMap = new Map();
router.post("/voice", async (ctx, next) => {
// call a API here
const params = {
data: "xxx",
callback_url: "http//myhost/ret_callback",
};
const req = new Request("http://xxx/api", {
method: "POST",
body: JSON.stringify(params),
});
const resp = await fetch(req);
const data = await resp.json();
const result = await waitForCallback(data.taskid);
ctx.body = {
result,
} })
const waitForCallback = (taskId) => {
return new Promise((resolve, reject) => {
const task = {};
task.id = taskId;
task.onComplete = (data) => {
resolve(data);
};
task.onError = () => {
reject();
};
taskMap.set(task.id, task);
});
};
router.post("/ret_callback", async (ctx, next) => {
const params = ctx.request.body;
// taskid will tell me this answer to which question
const taskid = params.taskid;
// this is exactly what I want
const result = params.text;
// here you continue the waiting response
taskMap.get(taskid).onComplete(result);
// not forget to clean rubbish
taskMap.delete(taskid);
ctx.body = {
code: 0,
message: "success",
}; })
我没有测试它,但我认为它会起作用。
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