Cómo actualizar elementos de matriz múltiples en mongodb

Question

Tengo un documento Mongo que contiene una matriz de elementos.

Me gustaría restablecer el atributo .handled de todos los objetos de la matriz donde .profile = XX.

El documento está en la forma siguiente:

{
    "_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": "....."
        }
        ...
    ]
}

Por lo tanto, he intentado lo siguiente:

.update({"events.profile":10},{$set:{"events.$.handled":0}},false,true)

Sin embargo se actualiza sólo el primero emparejado elemento de la matriz en cada documento. (Ese es el comportamiento definido para $ - el operador posicional ).

¿Cómo puedo actualizar todos elementos de la matriz emparejado?

Answer 1

En este momento no es posible utilizar el operador posicional para actualizar todos los elementos de una matriz. Ver JIRA http://jira.mongodb.org/browse/SERVER-1243

Como solución se puede:

• Actualización de cada elemento individual (Events.0.handled events.1.handled ...) o ...
• Lea el documento, hacer las ediciones manualmente y guardarlo sustitución de la uno de más edad (comprobar "Actualizar si Actual " si se quiere garantizar actualizaciones atómicas)

Answer 2

Lo que funcionó para mí fue la siguiente:

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);
  });

Creo que es más clara para los novatos mongo y cualquiera que esté familiarizado con jQuery y amigos.

Answer 3

Con la href="https://docs.mongodb.com/master/release-notes/3.6/#arrayfilters" liberación de MongoDB 3,6 (y disponible en el rama de desarrollo de MongoDB 3.5.12) ahora se puede actualizar varios elementos de matriz en una sola solicitud.

Esto utiliza la sintaxis operador Filtered posicional $[<identifier>] actualización introducido en esta versión:

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

El "arrayFilters" como los pasados ??a las opciones para .update() o incluso .updateOne() , .updateMany() , .findOneAndUpdate() o .bulkWrite() método especifica las condiciones para que coincida con el identificador dado en la instrucción de actualización. Cualquier elemento que coinciden con la condición dada se actualizarán.

Tras señalar que la "multi" como se da en el contexto de la pregunta se utilizó en la expectativa de que esto sería "actualizar varios elementos", pero esto no era y todavía no es el caso. Es el uso de aquí se aplica a "múltiples documentos" como siempre ha sido el caso ahora o se especifique lo contrario como el ajuste obligatorio de .updateMany() en las versiones modernas API.

Nota: Irónicamente, ya que esto se especifica en las "opciones" argumento para .update() y como métodos, la sintaxis es generalmente compatible con todas las versiones de los controladores reciente liberación.

Sin embargo esto no es cierto de la cáscara mongo, ya que la forma en que el método se implementa allí ( "irónicamente de compatibilidad hacia atrás") el argumento arrayFilters no es reconocido y eliminado por un método interno que analiza las opciones a fin de entregar " compatibilidad hacia atrás" con las versiones anteriores del servidor MongoDB y una 'sintaxis de llamada API .update() legado'.

Así que si desea utilizar el comando en el Shell mongo o de otro tipo "Shell basada" productos (en particular Robo 3T) necesita una versión más reciente de cualquiera de la rama de desarrollo o la liberación de producción a partir de 3,6 o superior.

positional all $[] que también actualiza "matriz múltiple elementos", pero sin aplicar a las condiciones especificadas y se aplica a todos elementos de la matriz donde que es la acción deseada.

También ver Actualización de una matriz anidada con MongoDB de cómo estos nuevos operadores posicionales se aplican a estructuras de matriz "anidados", donde "matrices son matrices dentro de otros".

IMPORTANTE - instalaciones actualizados de versiones anteriores "puede" haber permitido que no cuenta con MongoDB, que también pueden causar declaraciones a fallar. Debe asegurarse de que su procedimiento de actualización se completa con detalles tales como actualizaciones de índice y luego ejecutar

   db.adminCommand( { setFeatureCompatibilityVersion: "3.6" } )

o superior versión que es aplicable a su versión instalada. es decir "4.0" para la versión 4 y en adelante en el presente. Esto permitió a características tales como los nuevos operadores de actualización de posición y otros. También puede consultar con:

   db.adminCommand( { getParameter: 1, featureCompatibilityVersion: 1 } )

Para devolver el ajuste actual

Answer 4

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() > 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.

Answer 5

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:

1. 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.

2. 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.

Answer 6

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<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

Answer 7

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<Scene>.Filter.Where(i => i.ID != null);
   var update = Builders<Scene>.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

Answer 8

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

Answer 9

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.

Answer 10

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 =>{
    if(!usr)  return
    usr.events.forEach( e => {
      if(e && e.profile==10 ) e.handled = 0
    })
    User.findOneAndUpdate(
      {'_id': '4d2d8deff4e6c1d71fc29a07'},
      {$set: {events: usr.events}},
      {new: true}
    ).lean().exec().then(updatedUsr => console.log(updatedUsr))
})

Answer 11

$[] operator selects all nested array ..You can update all array items with '$[]'

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

Reference

Answer 12

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.

Answer 13

I just wanted to add another solution that worked for me and is pretty straightforward. Here it's just an array of tags (strings) so to update a tag called "test" to "changed", just do this:

myDocuments.find({tags: "test" }, {fields: {_id: 1}}).forEach(function (doc) {
    myDocuments.update(
        {_id: doc._id, tags: "test"}, 
        {$set:{'tags.$': "changed"}});
    });