Updating nested array inside array mongodb

问题:

I have the following mongodb document structure:

[
    {
        "_id": "04",
        "name": "test service 4",
        "id": "04",
        "version": "0.0.1",
        "title": "testing",
        "description": "test",
        "protocol": "test",
        "operations": [
            {
                "_id": "99",
                "oName": "test op 52222222222",
                "sid": "04",
                "name": "test op 52222222222",
                "oid": "99",
                "description": "testing",
                "returntype": "test",
                "parameters": [
                    {
                        "oName": "Param1",
                        "name": "Param1",
                        "pid": "011",
                        "type": "582",
                        "description": "testing",
                        "value": ""
                    },
                    {
                        "oName": "Param2",
                        "name": "Param2",
                        "pid": "012",
                        "type": "58222",
                        "description": "testing",
                        "value": ""
                    }
                ]
            }
        ]
    }
]

I have been able to use $elemMatch in order to update fields in operations, but when I try to do the same thing (modified) for parameters it does not seem to work. I was wondering what other approach should I look into trying in order to be able to successfully update fields in a specific parameter, looking it up by its pid.

The update code I currently have and does not work looks like this:

var oid = req.params.operations;
var pid = req.params.parameters;

collection.update({"parameters":{"$elemMatch": {"pid": pid}}},{"$set": {"parameters.$.name":req.body.name, "parameters.$.description": req.body.description,"parameters.$.oName": req.body.oName,"parameters.$.type": req.body.type} }, function(err, result) {
        if (err) {
            console.log('Error updating service: ' + err);
            res.send({'error':'An error has occurred'});
        } else {
            // console.log('' + result + ' document(s) updated');
            res.send(result);
        }
    });

回答1:

As @wdberkeley mentioned in his comment:

MongoDB doesn't support matching into more than one level of an array. Consider altering your document model so each document represents an operation, with information common to a set of operations duplicated in the operation documents.

I concur with the above and would recommend redesigning your schema as MongoDB engine does not support multiple positional operators ( See Multiple use of the positional $ operator to update nested arrays)

However, if you know the index of the operations array that has the parameters object to be updated beforehand then the update query will be:

db.collection.update(
    {
        "_id" : "04", 
        "operations.parameters.pid": "011"
    }, 
    {
        "$set": { 
            "operations.0.parameters.$.name": "foo",
            "operations.0.parameters.$.description": "bar", 
            "operations.0.parameters.$.type": "foo" 
        }
    }
)

EDIT:

If you would like to create the $set conditions on the fly i.e. something which would help you get the indexes for the objects and then modify accordingly, then consider using MapReduce.

Currently this seems to be not possible using the aggregation framework. There is an unresolved open JIRA issue linked to it. However, a workaround is possible with MapReduce. The basic idea with MapReduce is that it uses JavaScript as its query language but this tends to be fairly slower than the aggregation framework and should not be used for real-time data analysis.

In your MapReduce operation, you need to define a couple of steps i.e. the mapping step (which maps an operation into every document in the collection, and the operation can either do nothing or emit some object with keys and projected values) and reducing step (which takes the list of emitted values and reduces it to a single element).

For the map step, you ideally would want to get for every document in the collection, the index for each operations array field and another key that contains the $set keys.

Your reduce step would be a function (which does nothing) simply defined as var reduce = function() {};

The final step in your MapReduce operation will then create a separate collection operations that contains the emitted operations array object along with a field with the $set conditions. This collection can be updated periodically when you run the MapReduce operation on the original collection. Altogether, this MapReduce method would look like:

var map = function(){
    for(var i = 0; i < this.operations.length; i++){
        emit( 
            {
                "_id": this._id, 
                "index": i 
            }, 
            {
                "index": i, 
                "operations": this.operations[i],            
                "update": {
                    "name": "operations." + i.toString() + ".parameters.$.name",
                    "description": "operations." + i.toString() + ".parameters.$.description",
                    "type": "operations." + i.toString() + ".parameters.$.type"
                }                    
            }
        );
    }
};

var reduce = function(){};

db.collection.mapReduce(
    map,
    reduce,
    {
        "out": {
            "replace": "operations"
        }
    }
);

Querying the output collection operations from the MapReduce operation will typically give you the result:

db.operations.findOne()

Output:

{
    "_id" : {
        "_id" : "03",
        "index" : 0
    },
    "value" : {
        "index" : 0,
        "operations" : {
            "_id" : "96",
            "oName" : "test op 52222222222",
            "sid" : "04",
            "name" : "test op 52222222222",
            "oid" : "99",
            "description" : "testing",
            "returntype" : "test",
            "parameters" : [ 
                {
                    "oName" : "Param1",
                    "name" : "foo",
                    "pid" : "011",
                    "type" : "foo",
                    "description" : "bar",
                    "value" : ""
                }, 
                {
                    "oName" : "Param2",
                    "name" : "Param2",
                    "pid" : "012",
                    "type" : "58222",
                    "description" : "testing",
                    "value" : ""
                }
            ]
        },
        "update" : {
            "name" : "operations.0.parameters.$.name",
            "description" : "operations.0.parameters.$.description",
            "type" : "operations.0.parameters.$.type"
        }
    }
}

You can then use the cursor from the db.operations.find() method to iterate over and update your collection accordingly:

var oid = req.params.operations;
var pid = req.params.parameters;
var cur = db.operations.find({"_id._id": oid, "value.operations.parameters.pid": pid });

// Iterate through results and update using the update query object set dynamically by using the array-index syntax.
while (cur.hasNext()) {
    var doc = cur.next();
    var update = { "$set": {} };
    // set the update query object
    update["$set"][doc.value.update.name] = req.body.name;
    update["$set"][doc.value.update.description] = req.body.description;
    update["$set"][doc.value.update.type] = req.body.type;

    db.collection.update(
        {
            "_id" : oid, 
            "operations.parameters.pid": pid
        }, 
        update 
    );
};

回答2:

If it is data that is changed frequently, you should flatten the structure and separate the data that changes a lot from that which does not.

If it is data that does not change often, and the entire data object is not massive, just modify the object client-side, and update the entire object.

回答3:

We will try to find index of outer array(i) and inner array(j)and then update

collection.findById(04)
.then(result =>{
    for(let i = 0; i<result.operations.length; i++){
        if(result.operation[i]._id == "99"){
            let parameters = result.operations[i].parameters;`enter code here`
            for(let j = 0; j<parameters.length; j++){
                if(parameters[j].pid == "011"){
                    console.log("i", i);
                    console.log("j", j);
                    let data = {}
                    data["operations." + i + ".parameters." + j + ".oName"] = updateoName
                    data["operations." + i + ".parameters." + j + ".name"] = updatename
                    data["operations." + i + ".parameters." + j + ".pid"] = updatepid
                    data["operations." + i + ".parameters." + j + ".description"] = updatedescription
                    data["operations." + i + ".parameters." + j + ".value"] = updatevalue
                    console.log(data)
                    collection.update({
                        "_id": "04"
                    },{
                        $set: data
                    })
                    .then(dbModel => res.json(dbModel))
                }
            }
        }
    }
})

回答4:

Starting with mongo version 3.6 you can use the $[] in Conjunction with $[] to Update Nested Arrays

Update Nested Arrays in Conjunction with $[]

The $[] filtered positional operator, in conjunction with all $[] positional operator can be used to update nested arrays.

https://docs.mongodb.com/manual/reference/operator/update/positional-filtered/#position-nested-arrays-filtered