TypeError: Cannot use 'in' operator to search for '_id' in male

Question

Hi i am having issue with using the new versions of node.js Earlier i used a code like this ``` label(for='user_sex') Sex: select(id='user_sex', name='user[sex]') option(id='user_male',value=user.sex,selected=1)='male' option(id='user_female',value=user.sex)='female' ``` And code in app.js ``` var user = new User(req.body.user); -- other code var sex = new User(req.body.user.sex); User.find({}, function(err, users) { for(var i = 0;i< users.length;i++) { if(users[i].email == email) { useremail = users[i].email; } } if(!useremail) { user.save(function(err) { if (err) return userSaveFailed(); req.flash('info', 'Your account has been created'); emails.sendWelcome(user); switch (req.params.format) { case 'json': res.send(user.toObject()); break; default: req.session.user_id = user.id; res.redirect('/userinfo'); } }); } ``` The complete error log is as follows: ``` 500 TypeError: Cannot use 'in' operator to search for '_id' in male at model.Document.$__buildDoc (C:\SocialNetwork
ode_module…

Accepted Answer

You are getting this error because you're not constructing your model instance properly. It expects a hash of properties and their corresponding values but the parameter you're are providing is a string instead. From your code above, req.body.user is a hash `{sex: "male"}` whereas req.body.user.sex is just a string "male". You can do;

```
user = new User({sex: "male"});
```

But you can't do;

```
user = new User("male");
```

That explains why your first "User" instance with req.body.user parameter works but fails with req.body.user.sex parameter. I'm not sure yet what you're trying to achieve with `var sex = new User(req.body.user.sex);` Do you want to create another User model instance? or an associated sex model?

TypeError: Cannot use 'in' operator to search for '_id' in male

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