使用Unsplash API在NODEJS中的JSON输入的意外结束

Question

当我从API恢复数据时，我正在使用nodejs中的Unplash API，但我尝试解析数据，但我会得到JSON的错误意外端。

---

代码：

        const express = require("express");
        const https = require("https");
        const app = express();
        const port = 4000;
//      app.use(express.urlencoded({ extended: true }));
        app.use(express.static("public"));
        app.set("view engine", "ejs");
        app.get("/", (req, res) => {
      
          const url ="https://api.unsplash.com/photos/?client_id=ipLjiRmWcJ-jWn5uG8UhibNGiFgHxTVE_KeHHb8Oo3M";
          https.get(url, (response) => {
           status_code = response.statusCode;
           if (status_code == 200) {
             try {
              response.on("data", (data) => {
               var data_str = data.toString();

               console.log(JSON.parse(data_str));
             });
          } catch (error) {
            console.log(error);
          }
              res.send();
        }
      });
    });

    app.listen(port, () => console.log(`connected to port: ${port}`));

========================================== ==================

---

错误： [在此处输入图像描述] [1]

---

undefined:1
[{"id":"3f04FMm_Jqk","created_at":"2022-03-31T10:33:43-04:00","updated_at":"2022-06-25T17:25:36-04:00","promoted_at":null,"width":6048,"height":4024,"color":"#8c8c73","blur_hash":"LLE2nHWB0KVse.ozIoxaM{i_s:S4","description":null,"alt_description":null,"urls":{"raw":"https://images.unsplash.com/photo-1648737119359-510d4f551382?ixid=MnwzNDEyNDR8MXwxfGFsbHwxfHx8fHx8Mnx8MTY1NjI2NjU2OQ\u0026ixlib=rb-1.2.1","full":"https://images.unsplash.com/photo-1648737119359-510d4f551382?crop=entropy\u0026cs=tinysrgb\u0026fm=jpg\u0026ixid=MnwzNDEyNDR8MXwxfGFsbHwxfHx8fHx8Mnx8MTY1NjI2NjU2OQ\u0026ixlib=rb-1.2.1\u0026q=80","regular":"https://images.unsplash.com/photo-1648737119359-510d4f551382?crop=entropy\u0026cs=tinysrgb\u0026fit=max\u0026fm=jpg\u0026ixid=MnwzNDEyNDR8MXwxfGFsbHwxfHx8fHx8Mnx8MTY1NjI2NjU2OQ\u0026ixlib=rb-1.2.1\u0026q=80\u0026w=1080","small":"https://images.unsplash.com/photo-1648737119359-510d4f551382?crop=entropy\u0026cs=tinysrgb\u0026fit=max\u0026fm=jpg\u0026ixid=MnwzNDEyNDR8MXwxfGFsbHwxfHx8fHx8Mnx8MTY1NjI2NjU2OQ\u0026ixlib=rb-1.2.1\u0026q=80\u0026w=400","thumb":"https://images.unsplash.com/photo-1648737119359-510d4f551382?crop=entropy\u0026cs=tinysrgb\u0026fit=max\u0026fm=jpg\u0026ixid=MnwzNDEyNDR8MXwxfGFsbHwxfHx8fHx8Mnx8MTY1NjI2NjU2OQ\u0026ixlib=rb-1.2.1\u0026q=80\u0026w=200","small_s3":"https://s3.us-west-2.amazonaws.com/images.unsplash.com/small/pho

SyntaxError: Unexpected end of JSON input
    at JSON.parse (<anonymous>)
    at IncomingMessage.<anonymous> (C:\Users\Muslim Shah\Documents\express\unsplash\app.js:19:28)
    at IncomingMessage.emit (node:events:527:28)
    at addChunk (node:internal/streams/readable:315:12)
    at readableAddChunk (node:internal/streams/readable:289:9)
    at IncomingMessage.Readable.push (node:internal/streams/readable:228:10)
    at HTTPParser.parserOnBody (node:_http_common:141:24)
    at TLSSocket.socketOnData (node:_http_client:494:22)
    at TLSSocket.emit (node:events:527:28)
    at addChunk (node:internal/streams/readable:315:12)
[nodemon] app crashed - waiting for file changes before starting...

我尝试的 我尝试先将数据转换为字符串然后解析，但错误是相同的

Answer 1

诊断

您对响应的处理假设单个数据已发出提供完整响应数据的事件。

但是，这个假设是不正确的。 stream.able类，其中查询响应是一个子类实例，通过反复发射data事件来提供块中的内容。流的结尾由专用结束事件发出信号。

因此，必须首先收集响应数据并重新组装，然后再将其传递给JSON解析器。

代码

警告：此代码未经测试。

const express = require("express");
const https = require("https");
const app = express();
const port = 4000;
//      app.use(express.urlencoded({ extended: true }));
app.use(express.static("public"));
app.set("view engine", "ejs");
app.get("/", (req, res) => {

    const url ="https://api.unsplash.com/photos/?client_id=ipLjiRmWcJ-jWn5uG8UhibNGiFgHxTVE_KeHHb8Oo3M";
    https.get(url, (response) => {
        status_code = response.statusCode;
        if (status_code == 200) {
            // Watch out here:
            //  - Response data is delivered in chunks
            //  - If your next processing step operates on the whole response data, you need to collect the chunks into one string first.
            //  - Your dat ais ready for further processing when the `end` event is received.
            //
            let data_complete = ''
              ;
              
            try {
                response.on("data", (data_chunk) => {
                    data_complete += data_chunk.toString();
                });
                response.on("end", () => {
                    console.log(JSON.parse(data_complete));
                });
            } catch (error) {
                console.log(error);
            }
            res.send();
        }
   });
});

注意

周围可能有JSON解析器直接在流中运行。但是，基本的代码结构（数据用于重复调用的处理程序餐饮提供了块数据，end处理程序启动下一个处理步骤）不会更改

参考

node.js（v18.4.0）stream.able文档： https://nodejs.org/dist/latest-v18.x/docs/api/stream.html#class-streamreamreadable docs。可以通过更换上面链接中的主要版本编号来找到其他版本的node.js的文档（但是，您观察到的效果没有改变的基本机制）