Question

希望您能为我提供帮助，因为这是尝试解决此问题的时间。我已经在Google上搜索了很多东西，并尝试了所有发现的解决方案，但是我一直遇到同样的错误。我试图使一个轴获得对每页1个结果分页的API的请求，循环遍历所有结果，并使用promise数组解析promise。我已经验证，没有循环，仅收到1个请求，一切正常。我已经成功地使用MongoDB驱动程序写了MongoDB了。一旦陷入循环，我将无法兑现承诺。我能够console.log看到，promise数组的确确实有x个待处理的promise。

const MongoClient = require('mongodb')
const axios = require('axios');
const url = 'https://catfact.ninja/fact'

let db = null;
let client = null;

//this one works great
const getMetaData = function () {  
    let data = axios.get(url+"s")
    .then(response => {
        return response.data
    }).catch(error => console.log(error));
   return data;
}
//this one will not resolve
const dataArray =  async function (total) {
    let baseUrl = url+"s/facts?page="
    let res =[];    
    let promises = [];
    for (let page = 1; page <= total; page++){
        promises.push(axios.get(baseUrl+page))
    }
    axios.all(promises).then(result => console.log(result))
   //originally i wanted to map the result to an array of json
  //objects, but if i could even get a console.log it would be
 //a win. spread operator not working, Promise.all not working
 //i must have tried 12 different stackoverflow responses from
//other questions. until i can resolve the promises I can't do anything.


    }








exports.connect = async function(url, done) {
    if (db) return done();

   // let data = await getMetaData()
   // let total = data['total']
    let arr = dataArray(5);


    //console.log("arr is "+arr)
    MongoClient.connect(url, {useNewUrlParser: true}, function (err, client){
        if (err) return done(err);
        client = client;
        db = client.db('morefun');    
        /*
        db.collection('catfacts').insertMany(dataArray, function(err, res){
            if (err) throw err;
            console.log("Inserted: " + res.insertedCount);
        })*/
        done();


    });


}

exports.get = function() {
    return db;
}

//make sure this is correct
exports.close = function(done) {
    if (db) {
        client.close(function(err, result) {
            db = null;
            mode = null;
            done(err);
        });
    }
}

我需要一个JSON对象数组才能使insertMany函数起作用。请有人帮我。我究竟做错了什么？

Answer 1

在 for 循环中，您正在创建如下所示的URL：https://catfact.ninja/facts/facts?page=1 –这是不正确的，正确的URL应该为https://catfact.ninja/facts?page=1（带有 facts < / em>仅一次）。

此外，此处不需要关键字async，您应该返回axios.all的结果。

您的代码的正确版本：

const dataArray = function (total) { let baseUrl = url+"s?page=" let res =[]; let promises = []; for (let page = 1; page <= total; page++){ promises.push(axios.get(baseUrl+page)) } return axios.all(promises).then(result => { console.log(result); return result; }); }

然后您可以像这样获取数据：

let arr = await dataArray(5);

以所需的方式获取实际数据

从您的评论中，我看到您真正想要的是对从API获得的数据进行后处理，以最终获得一个仅包含cat数据的数组。

您可以通过使用map和reduce“按摩”数据来做到这一点，就像这样：

return axios .all(promises) .then(result => result.map(({ data }) => data.data).reduce((curr, acc) => acc.concat(curr), []));

注意：为了简洁起见，这里省略了console.log语句。

实际数据作为属性'data'嵌套在对象中，作为属性'data'，因此 map 调用检索该对象

我们得到一个数组数组，每个数组都有一个带有cat数据的对象； reduce 调用将其展平为简单的cat数据数组

我们得到的结果看起来像这样，希望是您想要的：

[ { "fact": "Cats see six times better in the dark and at night than humans.", "length": 63 }, { "fact": "The ability of a cat to find its way home is called “psi-traveling.” Experts think cats either use the angle of the sunlight to find their way or that cats have magnetized cells in their brains that act as compasses.", "length": 220 }, { "fact": "Cat's urine glows under a black light.", "length": 38 }, { "fact": "There are more than 500 million domestic cats in the world, with approximately 40 recognized breeds.", "length": 100 }, { "fact": "A tomcat (male cat) can begin mating when he is between 7 and 10 months old.", "length": 76 } ]

Answer 2

不确定这是否是答案，但我知道我在不使用axios想要完全用于axios的语法时遇到了问题。

axios.all([fetch1request(), fetch2request()]).then(axios.spread((fetch1, fetch2 ) => * whatever logic you need. But at this point the requests are complete* })

NodeJS中的Axios.all失败并显示404错误

2 个答案: