猫鼬查找，执行逻辑，然后在同一集合上进行更新

Question

I need to find a document, check some condition on its fields and perform an action or another depending on the outcome of a condition. This is inside a request handling so I must return different things in the response depending on the outcomes.

I have a solution done with findOneAndUpdate and if the returned records are 0 I return an error status, but I am curious to understand why the following doesn't work:

Users.findOne({'username':someVariable}).then((output)=>{

     if(output.someFiled > someCondition){
          Users.update(
              {'username':someVariable},
              {$set: {....}}
          ).then((error, num, success) =>{
              if(success){
                  return res.status(200).send('UPDATE OK');
              }
              if(error){
                  return res.status(500).....;
              }
          });
     } else {
         return res.status(404).....;
     }        

}).catch(....;

In particular the Users.update inside the find.then always return num:

{ ok: 0, n: 0, nModified: 0 }

Which means that no records were found although the record was indeed found with the first findOne.

EDIT: more information about the libraries, as maybe it's a matter of updating them (from package.json):

"bluebird": "^3.4.6",
"mongodb": "^3.0.2",
"mongoose": "^4.12.4",

Thanks, T.

Answer 1

Found the problem: the model file of the User didn't have the fields I was trying to update. The "find" part works also if the model has no declaration of such fields, but the "update" part won't.

So yea, just like that, should have read all the code but I thought it was boring.. never lucky.

Answer 2

you have to use (err,output) in findOne

Users.findOne({'username':someVariable}).then((err,output)=>{

     if(output.someFiled > someCondition){
          Users.update(
              {'username':someVariable},
              {$set: {....}}
          ).then((error, num, success) =>{
              if(success){
                  return res.status(200).send('UPDATE OK');
              }
              if(error){
                  return res.status(500).....;
              }
          });
     } else {
         return res.status(404).....;
     }        

}).catch(....;