javascript - Update multiple documents in MongoDB by altering object in array -

i have simple application registration/login , coursera/udemy type, app lists specific courses , users can them or enroll in them. have been trying make mongodb function updates user in database , since users can courses has update courses (courses have field "usersliked", array , keep user documents have liked it).

the course structure following:

{     "_id" : objectid("5977662564aac9f6c8d48884"),     "title" : "title",     "lecturer" : "lecturer",     "length" : 30,     "coverphoto" : "photo",     "usersliked": [          {             "_id" : objectid("597763e346a7a463cbb8f529"),             "fullname" : "name",             "username" : "username",             "password" : "hash",             "city" : "city",             "street" : "street",             "website" : "website"         }     ],     "lectures" : [          {             "title" : "introduction",             "number" : 1,             "url" : "someurl"         }     ] } 

and user structure:

{     "_id" : objectid("597763e346a7a463cbb8f529"),     "fullname" : "name",     "username" : "username",     "password" : "hash",     "enrolledcourses" : [          ...             ]         }     ],     "city" : "city",     "street" : "street",     "website" : "website" } 

so calling function when want change. changes usercollection in coursecollection nothing, while should courses , if of them have object username(the user's username) in "usersliked" array should modify user there too.

const updateuser = (username, details) => {         userscollection             .update({                 username: username,             }, {                 $set: {                     fullname: details.fullname,                     city: details.city,                     street: details.street,                     website: details.website,                 },             });         coursescollection             .updatemany(                 {                     usersliked: {                         $elemmatch: {                             username: username,                         },                     },                 },                 {                     $set: {                         'usersliked.username': details.username,                         'usersliked.city': details.city,                         'usersliked.street': details.street,                         'usersliked.website': details.website,                     },                 }             );     }; 

your match on course update looks valid trying set values array , according mongo docs need provide array indexer or positional operator.

the following allow set command operate on first element within usersliked array matches given username.

coursescollection.updatemany(     {         usersliked: {             $elemmatch: {                 username: username,             },         },     },     {         $set: {             'usersliked.$.username': details.username,             'usersliked.$.city': details.city,             'usersliked.$.street': details.street,             'usersliked.$.website': details.website         },     } ) 

you choose element in usersliked array update e.g. usersliked.1.username suspect each course has 1 element in usersliked given username in case using $ operator (which means: first matching array element) should suffice.