Nodejs Promise TypeError: Kann die Eigenschaft 'then' von undefined nicht lesen

Question

Ich habe einen Fehler, wenn ich versuche, auf die Funktion controller in meinem route zuzugreifen. Ich benutzte Mungo, Express.

Fehler:

TypeError: Cannot read property 'then' of undefined at /private/var/www/html/sms/server/routes/user.routes.js:70:9 at Layer.handle [as handle_request] (/private/var/www/html/sms/node_modules/express/lib/router/layer.js:95:5) at next (/private/var/www/html/sms/node_modules/express/lib/router/route.js:137:13) at Route.dispatch (/private/var/www/html/sms/node_modules/express/lib/router/route.js:112:3) at Layer.handle [as handle_request] (/private/var/www/html/sms/node_modules/express/lib/router/layer.js:95:5) at /private/var/www/html/sms/node_modules/express/lib/router/index.js:281:22 at Function.process_params (/private/var/www/html/sms/node_modules/express/lib/router/index.js:335:12) at next (/private/var/www/html/sms/node_modules/express/lib/router/index.js:275:10) at Function.handle (/private/var/www/html/sms/node_modules/express/lib/router/index.js:174:3) at router (/private/var/www/html/sms/node_modules/express/lib/router/index.js:47:12) at Layer.handle [as handle_request] (/private/var/www/html/sms/node_modules/express/lib/router/layer.js:95:5) at trim_prefix (/private/var/www/html/sms/node_modules/express/lib/router/index.js:317:13) at /private/var/www/html/sms/node_modules/express/lib/router/index.js:284:7 at Function.process_params (/private/var/www/html/sms/node_modules/express/lib/router/index.js:335:12) at next (/private/var/www/html/sms/node_modules/express/lib/router/index.js:275:10) at /private/var/www/html/sms/server.js:65:3 POST /api/user/create 500 27.274 ms - 16 (node:11300) UnhandledPromiseRejectionWarning: Unhandled promise rejection (rejection id: 1): Error: This email is already exists. Please enter another email. (node:11300) [DEP0018] DeprecationWarning: Unhandled promise rejections are deprecated. In the future, promise rejections that are not handled will terminate the Node.js process with a non-zero exit code.

hier ist mein Code: -

user.cont.js

function create(data) { 
    User.findOne({ email: data.email }) 
    .exec((err, doc) => { 
     if (err) { 
     return new Promise((resolve, reject) => { 
      return reject(err); 
     }) 
     } else { 
     if (doc) { 
      return new Promise((resolve, reject) => { 
      return reject(new Error('This email is already exists. Please enter another email.')); 
      }) 
     } else { 
      const user = new User(data); 
      return user.save() 
     } 
     } 

    }) 

} 


export default { getUsers, create }; 

user.route.js

router.post('/create', (req, res, next) => { 
     UserCtrl.create(req.body) 
      .then(savedUser => res.json(savedUser)) . // here error is generated 
      .catch(e => next(e)); 
    }); 

Answer 1

Sie sollen den ganzen User.findOne() Anruf in einem Versprechen wickeln, etwa so:

function create(data) { 
    return new Promise((resolve, reject) => { 
    User.findOne({ email: data.email }) 
     .exec((err, doc) => { 
     if (err) return reject(err) 
     if (doc) return reject(new Error('This email is already exists. Please enter another email.')) 
     const user = new User(data) 
     user.save((err) => { 
      if (err) return reject(err) 
      resolve() 
     }) 
     }) 
    }) 
} 

Sie müssen auch das Versprechen lösen, da sonst die Rückrufe in Ihren UserCtrl.then() Anrufen werden nie genannt werden. Ich fügte auch Fehlerbehandlung hinzu, falls etwas schief geht mit dem Speichern eines neuen User in der Datenbank.