How to Update Multiple Array Elements in mongodb

Question

I have a Mongo document which holds an array of elements   I d like to reset the  handled attribute of all objects in the array where  profile   XX   The document is in the following form            id   ObjectId  4d2d8deff4e6c1d71fc29a07         user id    714638ba-2e08-2168-2b99-00002f3d43c0        events                   handled   1               profile   10               data                                    handled   1               profile   10               data                                    handled   1               profile   20               data                                           so  I tried the following    update   events profile  10    set   events   handled  0   false true    However it updates only the first matched array element in each document   That s the defined behaviour for   - the positional operator    How can I update all matched array elements

User · Answer

Please be aware that some answers in this thread suggesting use $[] is WRONG.

db.collection.update(
   {"events.profile":10},
   {$set:{"events.$[].handled":0}},
   {multi:true}
)

The above code will update "handled" to 0 for all elements in "events" array, regardless of its "profile" value. The query {"events.profile":10} is only to filter the whole document, not the documents in the array. In this situation it is a must to use $[elem] with arrayFilters to specify the condition of array items so Neil Lunn's answer is correct.

User · Answer

operator selects all nested array   You can update all array items with          update   events profile  10    set   events     handled  0   false true    Reference

User · Answer

With the release of MongoDB 3 6   and available in the development branch from MongoDB 3 5 12   you can now update multiple array elements in a single request  This uses the filtered positional    lt identifier gt   update operator syntax introduced in this version  db collection update       quot events profile quot  10         quot  set quot      quot events   elem  handled quot   0           quot arrayFilters quot       quot elem profile quot   10      quot multi quot   true      The  quot arrayFilters quot  as passed to the options for  update   or even  updateOne     updateMany     findOneAndUpdate   or  bulkWrite   method specifies the conditions to match on the identifier given in the update statement  Any elements that match the condition given will be updated  Noting that the  quot multi quot  as given in the context of the question was used in the expectation that this would  quot update multiple elements quot  but this was not and still is not the case  It s usage here applies to  quot multiple documents quot  as has always been the case or now otherwise specified as the mandatory setting of  updateMany   in modern API versions   NOTE Somewhat ironically  since this is specified in the  quot options quot  argument for  update   and like methods  the syntax is generally compatible with all recent release driver versions  However this is not true of the mongo shell  since the way the method is implemented there    quot ironically for backward compatibility quot    the arrayFilters argument is not recognized and removed by an internal method that parses the options in order to deliver  quot backward compatibility quot  with prior MongoDB server versions and a  quot legacy quot   update   API call syntax  So if you want to use the command in the mongo shell or other  quot shell based quot  products   notably Robo 3T   you need a latest version from either the development branch or production release as of 3 6 or greater   See also positional all     which also updates  quot multiple array elements quot  but without applying to specified conditions and applies to all elements in the array where that is the desired action  Also see Updating a Nested Array with MongoDB for how these new positional operators apply to  quot nested quot  array structures  where  quot arrays are within other arrays quot    IMPORTANT - Upgraded installations from previous versions  quot may quot  have not enabled MongoDB features  which can also cause statements to fail  You should ensure your upgrade procedure is complete with details such as index upgrades and then run    db adminCommand    setFeatureCompatibilityVersion   quot 3 6 quot       Or higher version as is applicable to your installed version  i e  quot 4 0 quot  for version 4 and onwards at present  This enabled such features as the new positional update operators and others  You can also check with     db adminCommand    getParameter  1  featureCompatibilityVersion  1      To return the current setting

User · Answer

What worked for me was this   db collection find    id  ObjectId  4d2d8deff4e6c1d71fc29a07         forEach function  doc        doc events forEach function  event          if  event profile     10            event handled 0                      db collection save doc           I think it s clearer for mongo newbies and anyone familiar with JQuery  amp  friends

User · Answer

Update array field in multiple documents in mongo db   Use  pull or  push with update many query to update array elements in mongoDb   Notification updateMany          id      in  req body notificationIds                     pull     receiversId   req body userId          function  err            if  err                res status 500  json    msg   err               else               res status 200  json                    msg    Notification Deleted Successfully

User · Answer

I m amazed this still hasn t been addressed in mongo  Overall mongo doesn t seem to be great when dealing with sub-arrays  You can t count sub-arrays simply for example   I used Javier s first solution  Read the array into events then loop through and build the set exp   var set       i  l  for i 0 l events length i lt l i        if events i  profile    10        set  events     i     handled     0          update objId    set set      This can be abstracted into a function using a callback for the conditional test

User · Answer

First  your code did not work because you were using the positional operator   which only identifies an element to update in an array but does not even explicitly specify its position in the array   What you need is the filtered positional operator    lt identifier gt    It would update all elements that match an array filter condition    Solution   db collection update   events profile  10      set     events   elem  handled    0                multi  true       arrayFilters       elem profile   10          Visit mongodb doc here  What the code does       events profile  10  filters your collection and return the documents matching the filter The  set update operator  modifies matching fields of documents it acts on    multi true  It makes  update   modifies all documents matching the filter hence behaving like updateMany      events   elem  handled    0   and arrayFilters       elem profile   10     This technique involves the use of the filtered positional array with arrayFilters  the filtered positional array here   elem  acts as a placeholder for all elements in the array fields that match the conditions specified in the array filter    Array filters

User · Answer

You can update all elements in MongoDB db collectioname updateOne     quot key quot    vikas i       set       quot arr     status quot     quot completed quot         It will update all the  quot status quot  value to  quot completed quot  in the  quot arr quot  Array If Only one document db collectioname updateOne      key  quot someunique quot    quot arr key quot    quot myuniq quot          set           quot arr   status quot     quot completed quot          quot arr   msgs quot                            quot result quot     quot  quot                               But if not one and also you don t want all the documents in the array to update then you need to loop through the element and inside the if block db collectioname find  findCriteria       forEach function  doc        doc arr forEach function  singlearr          if  singlearr check            singlearr handled  0                     db collection save doc

User · Answer

The thread is very old  but I came looking for answer here hence providing new solution   With MongoDB version 3 6   it is now possible to use the positional operator to update all items in an array  See official documentation here   Following query would work for the question asked here  I have also verified with Java-MongoDB driver and it works successfully    update       or updateMany directly  removing the flag for  multi       events profile  10        set   events     handled  0        notice the empty brackets after     opearor    false     true     Hope this helps someone like me

User · Answer

This does in fact relate to the long standing issue at http   jira mongodb org browse SERVER-1243 where there are in fact a number of challenges to a clear syntax that supports  all cases  where mutiple array matches are found  There are in fact methods already in place that  aid  in solutions to this problem  such as Bulk Operations which have been implemented after this original post   It is still not possible to update more than a single matched array element in a single update statement  so even with a  multi  update all you will ever be able to update is just one mathed element in the array for each document in that single statement   The best possible solution at present is to find and loop all matched documents and process Bulk updates which will at least allow many operations to be sent in a single request with a singular response  You can optionally use  aggregate   to reduce the array content returned in the search result to just those that match the conditions for the update selection   db collection aggregate           match      events handled   1              project              events                   setDifference                        map                         input     events                       as    event                       in                              cond                                    eq        event handled   1                                    el                              false                                                                                  false                                    forEach function doc        doc events forEach function event            bulk find     id   doc  id   events handled   1     updateOne                 set      events   handled   0                       count             if   count   1000    0                 bulk execute                bulk   db collection initializeOrderedBulkOp                           if   count   1000    0       bulk execute      The  aggregate   portion there will work when there is a  unique  identifier for the array or all content for each element forms a  unique  element itself  This is due to the  set  operator in  setDifference used to filter any false values returned from the  map operation used to process the array for matches   If your array content does not have unique elements you can try an alternate approach with  redact   db collection aggregate           match      events handled   1              redact               cond                  if                       eq         ifNull       handled   1      1                               then      DESCEND                else      PRUNE                        Where it s limitation is that if  handled  was in fact a field meant to be present at other document levels then you are likely going to get unexepected results  but is fine where that field appears only in one document position and is an equality match   Future releases   post 3 1 MongoDB   as of writing will have a  filter operation that is simpler   db collection aggregate           match      events handled   1              project              events                   filter                      input     events                    as    event                    cond       eq        event handled   1                                         And all releases that support  aggregate   can use the following approach with  unwind  but the usage of that operator makes it the least efficient approach due to the array expansion in the pipeline   db collection aggregate           match      events handled   1              unwind     events             match      events handled   1              group               id      id            events       push     events                        In all cases where the MongoDB version supports a  cursor  from aggregate output  then this is just a matter of choosing an approach and iterating the results with the same block of code shown to process the Bulk update statements  Bulk Operations and  cursors  from aggregate output are introduced in the same version   MongoDB 2 6   and therefore usually work hand in hand for processing   In even earlier versions then it is probably best to just use  find   to return the cursor  and filter out the execution of statements to just the number of times the array element is matched for the  update   iterations   db collection find    events handled   1    forEach function doc        doc events filter function event   return event handled    1    forEach function event           db collection update     id   doc  id       set      events   handled   0                    If you are aboslutely determined to do  multi  updates or deem that to be ultimately more efficient than processing multiple updates for each matched document  then you can always determine the maximum number of possible array matches and just execute a  multi  update that many times  until basically there are no more documents to update   A valid approach for MongoDB 2 4 and 2 2 versions could also use  aggregate   to find this value   var result   db collection aggregate           match      events handled   1              unwind     events             match      events handled   1              group               id      id            count       sum   1                   group               id   null           count       max     count                var max   result result 0  count   while   max--         db collection update    events handled   1      set      events   handled   0       multi   true        Whatever the case  there are certain things you do not want to do within the update    Do not  one shot  update the array  Where if you think it might be more efficient to update the whole array content in code and then just  set the whole array in each document  This might seem faster to process  but there is no guarantee that the array content has not changed since it was read and the update is performed  Though  set is still an atomic operator  it will only update the array with what it  thinks  is the correct data  and thus is likely to overwrite any changes occurring between read and write  Do not calculate index values to update  Where similar to the  one shot  approach you just work out that position 0 and position 2   and so on   are the elements to update and code these in with and eventual statement like       set          events 0 handled   0       events 2 handled   0      Again the problem here is the  presumption  that those index values found when the document was read are the same index values in th array at the time of update  If new items are added to the array in a way that changes the order then those positions are not longer valid and the wrong items are in fact updated    So until there is a reasonable syntax determined for allowing multiple matched array elements to be processed in single update statement then the basic approach is to either update each matched array element in an indvidual statement   ideally in Bulk   or essentially work out the maximum array elements to update or keep updating until no more modified results are returned  At any rate  you should  always  be processing positional   updates on the matched array element  even if that is only updating one element per statement   Bulk Operations are in fact the  generalized  solution to processing any operations that work out to be  multiple operations   and since there are more applications for this than merely updating mutiple array elements with the same value  then it has of course been implemented already  and it is presently the best approach to solve this problem

User · Answer

UPDATE  As of Mongo version 3 6  this answer is no longer valid as the mentioned issue was fixed and there are ways to achieve this  Please check other answers   At this moment it is not possible to use the positional operator to update all items in an array  See JIRA http   jira mongodb org browse SERVER-1243 As a work around you can   Update each item individually  events 0 handled events 1 handled      or    Read the document  do the edits manually and save it replacing the older one  check  quot Update if Current quot  if you want to ensure atomic updates

User · Answer

I tried the following and its working fine    update   events profile   10       set     events   handled   0      safe  true  multi true    callback function        callback function in case of nodejs

User · Answer

This can also be accomplished with a while loop which checks to see if any documents remain that still have subdocuments that have not been updated  This method preserves the atomicity of your updates  which many of the other solutions here do not    var query         events             elemMatch                profile  10              handled     ne  0                       while  db yourCollection find query  count    gt  0        db yourCollection update          query             set     events   handled   0                multi  true              The number of times the loop is executed will equal the maximum number of times subdocuments with profile equal to 10 and handled not equal to 0 occur in any of the documents in your collection  So if you have 100 documents in your collection and one of them has three subdocuments that match query and all the other documents have fewer matching subdocuments  the loop will execute three times   This method avoids the danger of clobbering other data that may be updated by another process while this script executes  It also minimizes the amount of data being transferred between client and server

User · Answer

Actually  The save command is only on instance of Document class  That have a lot of methods and attribute  So you can use lean   function to reduce work load  Refer here  https   hashnode com post why-are-mongoose-mongodb-odm-lean-queries-faster-than-normal-queries-cillvawhq0062kj53asxoyn7j   Another problem with save function  that will make conflict data in with multi-save at a same time  Model Update will make data consistently  So to update multi items in array of document  Use your familiar programming language and try something like this  I use mongoose in that   User findOne    id    4d2d8deff4e6c1d71fc29a07    lean   exec      then usr   gt       if  usr   return     usr events forEach  e   gt          if e  amp  amp  e profile  10   e handled   0            User findOneAndUpdate           id    4d2d8deff4e6c1d71fc29a07            set   events  usr events           new  true        lean   exec   then updatedUsr   gt  console log updatedUsr

User · Answer

I ve been looking for a solution to this using the newest driver for C  3 6 and here s the fix I eventually settled on   The key here is using       which according to MongoDB is new as of version 3 6   See https   docs mongodb com manual reference operator update positional-all  up S   for more information   Here s the code        var filter   Builders lt Scene gt  Filter Where i   gt  i ID    null      var update   Builders lt Scene gt  Update Unset  area     discoveredBy       var result   collection UpdateMany filter  update  new UpdateOptions   IsUpsert   true        For more context see my original post here  Remove array element from ALL documents using MongoDB C  driver

[arrays] How to Update Multiple Array Elements in mongodb

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