在获取logging的过程中出现以下错误

我得到这个错误我得到这个错误提交后，我要去抓取logging它给这个错误。 当错误发生时，我给出了消息，不是错误，然后执行其他function。 我得到一些设置标题错误，所以请让我知道我错误的地方

/home/hacker201501/VAIBHAO/ndd/node_modules/mongoose/lib/utils.js:419 throw err; ^ Error: Can't set headers after they are sent. at ServerResponse.OutgoingMessage.setHeader (_http_outgoing.js:331:11) at ServerResponse.res.set.res.header (/home/hacker201501/VAIBHAO/ndd/node_modules/express/lib/response.js:524:10) at ServerResponse.res.json (/home/hacker201501/VAIBHAO/ndd/node_modules/express/lib/response.js:189:36) at Promise.<anonymous> (/home/hacker201501/VAIBHAO/ndd/app/controllers/categories_controller.js:110:26) at Promise.<anonymous> (/home/hacker201501/VAIBHAO/ndd/node_modules/mongoose/node_modules/mpromise/lib/promise.js:157:8) at Promise.EventEmitter.emit (events.js:107:17) at Promise.emit (/home/hacker201501/VAIBHAO/ndd/node_modules/mongoose/node_modules/mpromise/lib/promise.js:79:38) at Promise.reject (/home/hacker201501/VAIBHAO/ndd/node_modules/mongoose/node_modules/mpromise/lib/promise.js:106:15) at Promise.error (/home/hacker201501/VAIBHAO/ndd/node_modules/mongoose/lib/promise.js:89:15) at Query.execFind (/home/hacker201501/VAIBHAO/ndd/node_modules/mongoose/lib/query.js:1664:13) 

在这里，如果我getfunction

 exports.get_subcategory = function(req, res){ var subcategoryData = req.query; console.log('auth_token'); console.log(req.query.auth_token); console.log('query'); console.log(subcategoryData); User.findOne({auth_token: req.query.auth_token}, function(user_error, user){ if (user_error) res.json({status: 'Error', message: 'Login require'}); if (!user) res.json({status: 'Error', message: 'Invalid user'}); if (user){ SubCategory.find({category: req.query.category}, function(categoryError, subcatgory){ if (categoryError) res.json({status: 'Error', message: 'Category error'}); if (!subcatgory) res.json({status: 'Error', message: 'No category found'}); if (subcatgory) { res.json({status: 'OK', data: subcatgory}); } }) } }) } 

我不明白发生了什么事

Answer 1

我经历了你的代码，做了一些改变。 现在它应该工作，试试这个。

 exports.get_subcategory = function(req, res){ var subcategoryData = req.query; User.findOne({ auth_token: req.query.auth_token }, function(user_error, user){ if (user_error) res.json({status: 'Error', message: 'Login require'}); SubCategory.find( {category: req.query.category}, function(categoryError, subcatgory){ if (categoryError) res.json({status: 'Error', message: 'Category error'}); res.json({status: 'OK', data: subcatgory}); } ) } ) }