arrays - Update request in CRUD function -

i new sails , trying learn crud functions make first api, of ponzi coder tutorials, how create restful json crud api in sails scratch?

for update request, tried piece of code application "small",

module.exports = {      update: function (req, res, next) {         var criteria = {};         criteria = _.merge({}, req.params.all(), req.body);         var id = req.param('id');         if (!id) {             return res.badrequest('no id provided.');         }         small.update(id, criteria, function (err, small) {             if (err) return next(err);             if (small.length == 0) return res.notfound();             res.json(small);         });     }  }  

but unable understand significance , role of criteria array , second argument update function

small.update(id, criteria, function (err, small) {...}); 

i got criteria specifying changes want update, how ?

somebody please me out better understanding of this.

first of criteria not array empty object.

as of see in code line

criteria = _.merge({}, req.params.all(), req.body);

the above line signifies merging conditions sent in both parameters in url , body of post command using lodash object.

req.params.all() gives collection of parameters culled (in order of precedence):

1.the route (e.g. id in /post/:id).
2.the request body
3.the query string

according sails documentation update orm command updates existing records in database match specified criteria. have created sample example take _id body of post command. criteria on here column going update particular id.

crud.update(id,criteria,function(err,sleep){        if(sleep.length == 0) return res.badrequest();        if(err) return res.badrequest(err);        res.json(sleep);     });  }, 

hope answers question.