无法从JavaScript对象中读取值，始终为undefined。

huangapple
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英文:

Cant read vaules from JavaScript Object always undifined

问题

I can't retrieve values from a JavaScript object.

I have tried several ways but I can't get it to work the usual way i now but i am pretty new in javaScript.

Thanks for your time and attention, if there is anything missing or you need some more information please contact me.

The Object form console.log(unpackedReq)

  1. {
  2.  'mFile ': {
  3.     name: 'test',
  4.     data: { type: 'Buffer', data: [Array] },
  5.     size: 4,
  6.     encoding: '7bit',
  7.     tempFilePath: '',
  8.     truncated: false,
  9.     mimetype: 'application/octet-stream',
  10.     md5: '098f6bcd4621d373cade4e832627b4f6'
  11.   }
  12. }

My Code:

  1. app.post('/single', async (req, res, next) => {
  2. try {
  3.     
  4.     const unpackedReq = JSON.parse(JSON.stringify(req.files));
  5.     const file = unpackedReq.mFile
  7.     console.log(unpackedReq)
  8.     console.log(typeof(unpackedReq)) //object
  9.     console.log(unpackedReq["mFile"].name) // TypeError: Cannot read properties of undefined (reading 'name')
  12. } catch (error) {
  13.     console.log(error)
  14.     res.send('Error uploading file')
  15. }

The Full error:

  1. > TypeError: Cannot read properties of undefined (reading 'name')
  2. >     at /Users/lukasbronstering/VsCode/ftp-web-server/app.js:25:42
  3. >     at Layer.handle [as handle_request] (/Users/lukasbronstering/VsCode/ftp-web-server/node_modules/express/lib/router/layer.js:95:5)
  4. >     at next (/Users/lukasbronstering/VsCode/ftp-web-server/node_modules/express/lib/router/route.js:144:13)
  5. >     at Route.dispatch (/Users/lukasbronstering/VsCode/ftp-web-server/node_modules/express/lib/router/route.js:114:3)
  6. >     at Layer.handle [as handle_request] (/Users/lukasbronstering/VsCode/ftp-web-server/node_modules/express/lib/router/layer.js:95:5)
  7. >     at /Users/lukasbronstering/VsCode/ftp-web-server/node_modules/express/lib/router/index.js:284:15
  8. >     at Function.process_params (/Users/lukasbronstering/VsCode/ftp-web-server/node_modules/express/lib/router/index.js:346:12)
  9. >     at next (/Users/lukasbronstering/VsCode/ftp-web-server/node_modules/express/lib/router/index.js:280:10)
  10. >     at jsonParser (/Users/lukasbronstering/VsCode/ftp-web-server/node_modules/body-parser/lib/types/json.js:119:7)
  11. >     at Layer.handle [as handle_request] (/Users/lukasbronstering/VsCode/ftp-web-server/node_modules/express/lib/router/layer.js:95:5)
英文:

I can't retrieve values from a JavaScript object.

I have tried several ways but I can't get it to work the usual way i now but i am pretty new in javaScript.

Thanks for your time and attention, if there is anything missing or you need some more information please contact me.

The Object form consol.log(unpackedReq)

  1. {
  2.  'mFile ': {
  3.     name: 'test',
  4.     data: { type: 'Buffer', data: [Array] },
  5.     size: 4,
  6.     encoding: '7bit',
  7.     tempFilePath: '',
  8.     truncated: false,
  9.     mimetype: 'application/octet-stream',
  10.     md5: '098f6bcd4621d373cade4e832627b4f6'
  11.   }
  12. }

My Code:

  1. app.post('/single', async(req, res, next) => {
  2. try {
  3.     
  4.     const unpackedReq = JSON.parse(JSON.stringify(req.files));
  5.     const file = unpackedReq.mFile
  7.     console.log(unpackedReq)
  8.     console.log(typeof(unpackedReq)) //object
  9.     console.log(unpackedReq["mFile"].name) // TypeError: Cannot read properties of undefined (reading 'name')
  12. } catch (error) {
  13.     console.log(error)
  14.     res.send('Error uploading file')
  15. }

The Full error:

  1. > TypeError: Cannot read properties of undefined (reading 'name')
  2. >     at /Users/lukasbronstering/VsCode/ftp-web-server/app.js:25:42
  3. >     at Layer.handle [as handle_request] (/Users/lukasbronstering/VsCode/ftp-web-server/node_modules/express/lib/router/layer.js:95:5)
  4. >     at next (/Users/lukasbronstering/VsCode/ftp-web-server/node_modules/express/lib/router/route.js:144:13)
  5. >     at Route.dispatch (/Users/lukasbronstering/VsCode/ftp-web-server/node_modules/express/lib/router/route.js:114:3)
  6. >     at Layer.handle [as handle_request] (/Users/lukasbronstering/VsCode/ftp-web-server/node_modules/express/lib/router/layer.js:95:5)
  7. >     at /Users/lukasbronstering/VsCode/ftp-web-server/node_modules/express/lib/router/index.js:284:15
  8. >     at Function.process_params (/Users/lukasbronstering/VsCode/ftp-web-server/node_modules/express/lib/router/index.js:346:12)
  9. >     at next (/Users/lukasbronstering/VsCode/ftp-web-server/node_modules/express/lib/router/index.js:280:10)
  10. >     at jsonParser (/Users/lukasbronstering/VsCode/ftp-web-server/node_modules/body-parser/lib/types/json.js:119:7)
  11. >     at Layer.handle [as handle_request] (/Users/lukasbronstering/VsCode/ftp-web-server/node_modules/express/lib/router/layer.js:95:5)

答案1

得分: 2

对象'mFile '中有一个空格，但您在没有空格的情况下访问它。

因此，您可以在访问对象时添加空格，就像这样：console.log(unpackedReq["mFile "].name)，或者您可以更改对象。但我建议更改对象名称。

英文:

There is a space in object 'mFile ' and you're accessing it without space.

so you can just add the space while accessing your object like this console.log(unpackedReq["mFile "].name) or you could change your object. but i would recommend to change your object name

huangapple
  • 本文由 发表于 2023年2月10日 10:06:55
  • 转载请务必保留本文链接：https://go.coder-hub.com/75406286.html
  • express
  • javascript
  • json
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