我最近遇到了一个有趣的问题,我无法解决自己的生活。我正在调用将记录分成页面的API调用,页面的信息位于响应头中。因此,我希望能够再次调用以检索数据和下一个标头,直到没有更多响应标头为止。
let parents = {};
const options = {
credentials: "same-origin",
headers: {
accept: "application/json"
},
timeout: 5000
};
fetch(
`/api/v1/courses/200003/enrollments?enrollment_type=ObserverEnrollment&per_page=100`,
options
).then(response =>
response
.json()
.then(data => ({
data: data,
ok: response.ok,
headers: response.headers
}))
.then(res => {
parents = res;
nextURL(res.headers.get("Link"));
let optionsNext = {
credentials: "same-origin",
headers: {
accept: "application/json"
},
timeout: 5000
};
fetch(nextURL(res.headers.get("Link")), optionsNext).then(response =>
response
.json()
.then(data => ({
data: data,
ok: response.ok,
headers: response.headers
}))
.then(res => {
if (res.ok) {
parents.data.push(res.data);
console.info(parents);
}
})
);
})
);
function nextURL(linkTxt) {
let url = null;
if (linkTxt) {
let links = linkTxt.split(",");
let nextRegEx = new RegExp('^<(.*)>; rel="next"$');
for (let i = 0; i < links.length; i++) {
let matches = nextRegEx.exec(links[i]);
if (matches) {
url = matches[1];
}
}
}
return url;
}
我需要放入某种循环的部分是基于nextURL函数返回的辅助提取:if !nextURL(res.headers.get("Link"))
我需要break
循环。
let optionsNext = {
credentials: "same-origin",
headers: {
accept: "application/json"
},
timeout: 5000
};
fetch(nextURL(res.headers.get("Link")), optionsNext).then(response =>
response
.json()
.then(data => ({
data: data,
ok: response.ok,
headers: response.headers
}))
.then(res => {
if (res.ok) {
parents.data.push(res.data);
console.info(parents);
}
})
);
预先感谢您看我可怜的问题
答案 0 :(得分:2)
尝试使用递归;像这样的东西:
const getFetcher = () => ({
aggregate: [],
run: function (url, options) {
return new Promise((resolve, reject) => {
fetch(url, options)
.then(response => {
const json = response.json();
const { headers, data } = response;
const nextLink = res.headers.get("Link");
this.aggregate.push(data);
if (nextLink) {
this.run(nextLink, options).then(resolve);
}
else {
resolve(this.aggregate);
}
})
})
}
})
const options = {
credentials: "same-origin",
headers: {
accept: "application/json"
},
timeout: 5000
};
const fetcher = getFetcher();
fetcher.run(`/api/v1/courses/200003/enrollments?enrollment_type=ObserverEnrollment&per_page=100`, options)
.then(allPagesData => {
/* at this point you have all the pages data */
})
答案 1 :(得分:1)
使用异步递归函数。
我不确定您的api返回什么,但这应该可以工作:
首先,只要找到元素就可以返回它,如果元素太多,则可以节省一些迭代。
function nextURL(linkTxt) {
if (linkTxt) {
let links = linkTxt.split(",");
let nextRegEx = new RegExp('^<(.*)>; rel="next"$');
for (let i = 0; i < links.length; i++) {
let matches = nextRegEx.exec(links[i]);
if (matches && matches[1]) {
//return right away
return matches[1];
}
}
}
return null;
}
接下来定义您的主要通话:
const OPTIONS = {
credentials: "same-origin",
headers: {
accept: "application/json"
},
timeout: 5000
};
let parents = {};
async function main(){
const RESPONSE = await fetch(`/api/v1/courses/200003/enrollments?enrollment_type=ObserverEnrollment&per_page=100`,OPTIONS);
let data = await RESPONSE.json();
let res = {
data: data,
ok: RESPONSE.ok,
headers: RESPONSE.headers
}
loop(res);
//or:
//await loop(res);
//if you want to wait for it.
}
然后循环
const OPTIONS_NEXT = {
credentials: "same-origin",
headers: {
accept: "application/json"
},
timeout: 5000
};
async function loop(parents){
//if nextURL returns null...
if(nextURL(parents.headers.get("Link")),OPTIONS_NEXT === null)
//...end the loop
return;
//otherwise keep going.
const RESPONSE = await fetch(nextURL(parents.headers.get("Link")),OPTIONS_NEXT);
let data = await RESPONSE.json();
let res = {
data: data,
ok: RESPONSE.ok,
headers: RESPONSE.headers
}
if (res.ok) {
parents.data.push(res.data);
console.info(parents);
}
loop(res);
//or:
//await loop(res);
//if you want to wait for it.
//You need to call it from within an async function.
}
现在您需要做的就是调用主函数:
main();
//or:
//await main();
//if you want to wait for it.
//You need to call it from within an async function.