TypeError:无法读取未定义的属性“method”

Question

当试图为我们得到的方法运行RPC命令时，我似乎无法解决这个问题。它在本地工作，但不是在实时linux服务器上。

TypeError:无法读取C:\ssc exchange Transactions\app上未定义的属性“method”。第二层的js:23:13。在路由的下一个（C:\ssc exchange Transactions\node\u modules\express\lib\router\layer.js:95:5）处（C:\ssc exchange Transactions\node\u modules\express\lib\router\route.js:137:13）处理[作为句柄\u请求]（C:\ssc exchange Transactions\node\u modules\express\lib\router\route.js:。层上的调度（C:\ssc exchange Transactions\node\u modules\express\lib\router\route.js:112:3）。在C:\ssc exchange Transactions\node\u modules\express\lib\router\layer.js:95:5处处理[作为句柄\u请求]（C:\ssc exchange Transactions\node\u modules\express\lib\router\index）。js:281:22 at功能。在jsonParser（C:\ssc exchange Transactions\node\u modules\express\lib\router\index.js:335:12）的下一层（C:\ssc exchange Transactions\node\u modules\express\lib\router\index.js:275:10）中处理参数（C:\ssc exchange Transactions\node\u modules\body parser\lib\types\json.js:119:7）。handle[作为handle\u请求]（C:\ssc exchange transactions\node\u modules\express\lib\router\layer.js:95:5）

const express = require("express");
const bodyParser = require("body-parser");
const request = require("request");
const port = 5000;
const app = express();
app.use(bodyParser.urlencoded({ extended: true }));
app.use(bodyParser.json());
const dsteem = require('dsteem');
const client = new dsteem.Client('https://api.site.com');
app.set('trust proxy', true);
app.disable('x-powered-by');


app.post('/', function(req,res){
    try
    {
    var body=JSON.parse(req.body.curl);
    }
    catch(err)
    {
     res.send({msg: 'invalid command', error: err});
    }
    if(body.method !=undefined && body.method == "POST")
    {
    let options = {
      url:body.url,
      method:body.method,
      headers:body.headers,
      body: JSON.stringify(body.body)
    };
    request(options, (error, response, body) => {
      if (error) {
        console.error("An error has occurred: ", error);
        res.send(error);
      }
      else {
        let responseData = JSON.parse(body);
        res.send(responseData);
      }
    });
  }
  ///Ends if
  else if(body.method != undefined && body.method == "GET")
  {
    let options = {
    //   url: body.url+'?account='+body.body.params.account+'&limit='+body.body.params.limit+
    //   '&offset='+body.body.params.offset+'&&symbol='+body.body.params.symbol,
         url: 'https://api.site.com/accounts/history'+body.symbol,
         method: "GET",
         headers: {"Content-type": "application/json"},
    };
    request(options, (error, response, body) => {
      if (error) {
        console.error("An error has occurred: ", error);
        res.send(error);
      }
      else {
         var withdraw = [], deposit = [];
         body= JSON.parse(body);
         body.forEach(el => {
           if(el.from == "account"){
            delete el.block;
            delete el.symbol;
            delete el.from_type;
            delete el.to_type;
             withdraw.push(el);
           }
           else{
            delete el.block;
            delete el.symbol;
            delete el.from_type;
            delete el.to_type;
            deposit.push(el);
           }

         });
         res.json([{"WITHDRAWS": withdraw},{"DEPOSITS":deposit}]);
      }
    });
  }
  //ends else if
  else
  {
    const active_key = body.wif;
    const key = dsteem.PrivateKey.fromString(active_key);
    const account = "account";
    const my_id= "mainnet";
    const my_data= {"contractName":"tokens", "contractAction":"transfer","contractPayload":{"symbol": "omg",
    "to": body.to,"quantity":body.quantity,"memo": body.memo }};
    client.broadcast.json({
        required_auths: [account],
        required_posting_auths: [],
        id: my_id,
        json: JSON.stringify(my_data),
    }, key).then(
        result => {res.send(result)},
        error => {res.send({msg: 'Something went wrong', error: error})}
    )
  }
  //ends else
  });

app.listen(port, function () {
  console.log("Server listening on port: " + port);
});

Answer 1

您的代码在第一次尝试/捕获块中出现错误的情况下中断，这是您这边的语义错误。

try
{
  var body=JSON.parse(req.body.curl);
}
catch(err)
{
   res.send({msg: 'invalid command', error: err});
}

1.JS中的变量提升

检查js中变量hoising的主题：https://developer.mozilla.org/en-US/docs/Glossary/Hoisting

简而言之，根据您的示例，这意味着JS编译器将在post函数的最顶端创建一个名为body的变量，该变量的初始值为undefined。这是因为您使用了var关键字，而不是const/let。

只有在JSON. parse（）正常工作的情况下，才会设置body变量的值。如果出现这种情况（似乎发生在您身上）或出现错误，body将永久保持未定义状态，这意味着您无法访问其属性（如方法），因为它不是对象。

解决方案取决于您想在这里实现的目标：

1. 你可以把剩下的代码放在try/catwell里面
2. 您还可以添加一个额外的身体检查
3. 您可以重构代码，使其更具可读性（当然，这总是主观的，取决于编码风格）

这里有一个重构示例：

app.post('/', function(req, res) {
  try {
    const body = JSON.parse(req.body.curl);

    switch (body.method) {
      case 'GET':
        this.handleGETRequest();
      case 'POST':
        this.handlePOSTRequest();
      default:
        this.handleDefault();
    }
  } catch (err) {
    res.send({ msg: 'invalid command', error: err });
  }
});

如果您想避免分裂成几个函数，您可以执行以下操作

app.post('/', function(req, res) {
      try {
        const body = JSON.parse(req.body.curl);

        // Your current else 
        if(!body.method) {
            ...code
            return; // Will break the execution after this
        }

        ...your normal if/else here with simplified checks now
      } catch (err) {
        res.send({ msg: 'invalid command', error: err });
      }
    });

考虑到一切都包裹在里面，尝试/捕捉没有必要特别检查身体在这里未定义。