I have a collection which looks something like this:
{
paymentType: [1,2]
}
Using aggregation framework, I'm looking for a way to replace the values with certain string, for example 1 = A, 2 = B so that the final result look slike that:
{
paymentType: ['A','B']
}
I'm also using mongodb 2.4.
Please help,
Thanks!
The aggregation framework will never change the collection is acts on. The aggregation pipeline produces new documents (which are usually temporary and just piped out to the client). The simplest way to do this is just to grab each doc and replace the values, then update the field. Here's some code that has all the basic ideas:
> db.stuff.find({}, { "_id" : 1, "paymentType" : 1 }).forEach(function(doc) {
var new_paymentType = []
doc.paymentType.forEach(function(val) {
if (val === 1) new_paymentType.push("A")
if (val === 2) new_paymentType.push("B")
})
db.stuff.update({ "_id" : doc._id }, { "$set" : { "paymentType" : new_paymentType } })
})
Related
I have a collection in mongoDB which looks like,
collection:
doc1
{ field1 : {
field1_1 : 'val1',
field1_2 : 'val2',
field1_3 : 'val3',
...
field1_N : 'valN' } }
doc2
{ field1 : {
field1_1 : 'val1',
field1_2 : 'val2',
field1_3 : 'val3',
...
field1_N : 'valN' } }
I want to find aggregation(sum, avg, min, max) on val1, val2, val3 ... valN. Is there any way to use mongo's aggregation feature? The keys are always different, and the aggregation should happen for all the values of field1
Edited:
The final output should look like,
doc1
{ field1 : {
sum: sumOf(val1, val2... valN),
avg: avgOf(val1, val2... valN)
... } }
doc2
{ field1 : {
sum: sumOf(val1, val2... valN),
avg: avgOf(val1, val2... valN)
... } }
can try this one using Map-Reduce instead of aggregate for your requirement. map-reduce operations provide some flexibility that is not presently available in the aggregation pipeline.
var mapFunction =
function() {
for (key in this.field1) {
emit(this._id, parseInt(this.field1[key]));
}
};
var reduceFunction =
function(key, values) {
return {sum:Array.sum(values), avg:Array.avg(values)};
};
db.getCollection('collectionName').mapReduce(mapFunction, reduceFunction, {out: {inline:1}});
As far I know if your document structure would be like :
field1 : [
{field1 : 'val1'},
{field1 : 'val2'},
{field1 : 'val3'},
...
{field1 : 'valN'}]
then you could solved easily by using aggregate. so for your structure mapReducemay better.
I'm not a mongodb ninja by any means, but I've a solution for your question. It's not the most efficient one, but if you are royally stuck, you can use it.
So the code below, creates a projection, of the avg data of the fields that you want to aggregate (avg) on, the down side to this is that you have to specify each field, rather than maybe a way of iterating through all fields and aggregating on that. You can definitely do iterations using JS, I've briefly come across it in the past, but it might take a small bit more tweaking than the code I've provided below.
Also, I've assumed that, field1.field1_1 : "int". Is an integer and not a string value.
db.random.aggregate(
[
{
$project:
{
_id: "$field1",
avgAmount: { $avg: ["$field1.field1_1", "$field1.field1_2", "$field1.field1.3"]}
}
}]
)
Best of luck anyway #1love.
You can try $sum for sum and $multiply for multiplication.. you can find all the aggregate functions available for MongoDb at the following link:
https://docs.mongodb.com/manual/reference/operator/aggregation/sum/
hope this helps..
I have a "mongodb colllenctions" and I'd like to remove the "empty strings"with keys from it.
From this:
{
"_id" : ObjectId("56323d975134a77adac312c5"),
"year" : "15",
"year_comment" : "",
}
{
"_id" : ObjectId("56323d975134a77adac312c5"),
"year" : "",
"year_comment" : "asd",
}
I'd like to gain this result:
{
"_id" : ObjectId("56323d975134a77adac312c5"),
"year" : "15",
}
{
"_id" : ObjectId("56323d975134a77adac312c5"),
"year_comment" : "asd",
}
How could I solve it?
Please try executing following code snippet in Mongo shell which strips fields with empty or null values
var result=new Array();
db.getCollection('test').find({}).forEach(function(data)
{
for(var i in data)
{
if(data[i]==null || data[i]=='')
{
delete data[i]
}
}
result.push(data)
})
print(tojson(result))
Would start with getting a distinct list of all the keys in the collection, use those keys as your query basis and do an ordered bulk update using the Bulk API operations. The update statement uses the $unset operator to remove the fields.
The mechanism to get distinct keys list that you need to assemble the query is possible through Map-Reduce. The following mapreduce operation will populate a separate collection with all the keys as the _id values:
mr = db.runCommand({
"mapreduce": "my_collection",
"map" : function() {
for (var key in this) { emit(key, null); }
},
"reduce" : function(key, stuff) { return null; },
"out": "my_collection" + "_keys"
})
To get a list of all the dynamic keys, run distinct on the resulting collection:
db[mr.result].distinct("_id")
// prints ["_id", "year", "year_comment", ...]
Now given the list above, you can assemble your query by creating an object that will have its properties set within a loop. Normally your query will have this structure:
var keysList = ["_id", "year", "year_comment"];
var query = keysList.reduce(function(obj, k) {
var q = {};
q[k] = "";
obj["$or"].push(q);
return obj;
}, { "$or": [] });
printjson(query); // prints {"$or":[{"_id":""},{"year":""},{"year_comment":""}]}
You can then use the Bulk API (available with MongoDB 2.6 and above) as a way of streamlining your updates for better performance with the query above. Overall, you should be able to have something working as:
var bulk = db.collection.initializeOrderedBulkOp(),
counter = 0,
query = {"$or":[{"_id":""},{"year":""},{"year_comment":""}]},
keysList = ["_id", "year", "year_comment"];
db.collection.find(query).forEach(function(doc){
var emptyKeys = keysList.filter(function(k) { // use filter to return an array of keys which have empty strings
return doc[k]==="";
}),
update = emptyKeys.reduce(function(obj, k) { // set the update object
obj[k] = "";
return obj;
}, { });
bulk.find({ "_id": doc._id }).updateOne({
"$unset": update // use the $unset operator to remove the fields
});
counter++;
if (counter % 1000 == 0) {
// Execute per 1000 operations and re-initialize every 1000 update statements
bulk.execute();
bulk = db.collection.initializeOrderedBulkOp();
}
})
If you need to update a single blank parameter or you prefer to do parameter by parameter, you can use the mongo updateMany functionality:
db.comments.updateMany({year: ""}, { $unset : { year : 1 }})
I have a collection users as follows:
{ "_id" : ObjectId("51780f796ec4051a536015cf"), "userId" : "John" }
{ "_id" : ObjectId("51780f796ec4051a536015d0"), "userId" : "Sam" }
{ "_id" : ObjectId("51780f796ec4051a536015d1"), "userId" : "John1" }
{ "_id" : ObjectId("51780f796ec4051a536015d2"), "userId" : "john2" }
Now I am trying to write a code which can provides suggestions of a userId to user in case id provided by user already exists in DB. In same routine I just append values from 1 to 5 to the for example in case user have selected userId to be John, suggested user name array that needs to be checked for Id in database will look like this
[John,John1,John2,John3,John4,John5].
Now I just want to execute it against Db and to find out which of the suggested values do not exist in DB. So instead of selecting any document, I want to select values within suggested array which do not exist for users collection.
Any pointers are highly appreciated.
Your general approach here is you want to find the "distinct" values for the "userId's" that already exist in your collection. You then compare these to your input selection to see the difference.
var test = ["John","John1","John2","John3","John4","John5"];
var res = db.collection.aggregate([
{ "$match": { "userId": { "$in": test } }},
{ "$group": { "_id": "$userId" }}
]).toArray();
res.map(function(x){ return x._id });
test.filter(function(x){ return res.indexOf(x) == -1 })
The end result of this is the userId's that do not match in your initial input:
[ "John2", "John3", "John4", "John5" ]
The main operator there is $in which takes an array as the argument and compares those values against the specified field. The .aggregate() method is the best approach, there is a shorthand mapReduce wrapper in the .distinct() method which directly produces just the values in the array, removing the call to a function like .map() to strip out the values for a given key:
var res = db.collection.distinct("userId",{ "userId": { "$in": test } })
It should run notably slower though, especially on large collections.
Also do not forget to index your "userId" and likely you want this to be "unique" anyway so you really just want the $match or .find() result:
var res = db.collection.find({ "$in": test }).toArray()
I want to combine two mongodb collections.
Basically I have a collection containing documents that reference one document from another collection. Now I want to have this as a inline / nested field instead of a separate document.
So just to provide an example:
Collection A:
[{
"_id":"90A26C2A-4976-4EDD-850D-2ED8BEA46F9E",
"someValue": "foo"
},
{
"_id":"5F0BB248-E628-4B8F-A2F6-FECD79B78354",
"someValue": "bar"
}]
Collection B:
[{
"_id":"169099A4-5EB9-4D55-8118-53D30B8A2E1A",
"collectionAID":"90A26C2A-4976-4EDD-850D-2ED8BEA46F9E",
"some":"foo",
"andOther":"stuff"
},
{
"_id":"83B14A8B-86A8-49FF-8394-0A7F9E709C13",
"collectionAID":"90A26C2A-4976-4EDD-850D-2ED8BEA46F9E",
"some":"bar",
"andOther":"random"
}]
This should result in Collection A looking like this:
[{
"_id":"90A26C2A-4976-4EDD-850D-2ED8BEA46F9E",
"someValue": "foo",
"collectionB":[{
"some":"foo",
"andOther":"stuff"
},{
"some":"bar",
"andOther":"random"
}]
},
{
"_id":"5F0BB248-E628-4B8F-A2F6-FECD79B78354",
"someValue": "bar"
}]
I'd suggest something simple like this from the console:
db.collB.find().forEach(function(doc) {
var aid = doc.collectionAID;
if (typeof aid === 'undefined') { return; } // nothing
delete doc["_id"]; // remove property
delete doc["collectionAID"]; // remove property
db.collA.update({_id: aid}, /* match the ID from B */
{ $push : { collectionB : doc }});
});
It loops through each document in collectionB and if there is a field collectionAID defined, it removes the unnecessary properties (_id and collectionAID). Finally, it updates a matching document in collectionA by using the $push operator to add the document from B to the field collectionB. If the field doesn't exist, it is automatically created as an array with the newly inserted document. If it does exist as an array, it will be appended. (If it exists, but isn't an array, it will fail). Because the update call isn't using upsert, if the _id in the collectionB document doesn't exist, nothing will happen.
You can extend it to delete other fields as necessary or possibly add more robust error handling if for example a document from B doesn't match anything in A.
Running the code above on your data produces this:
{ "_id" : "5F0BB248-E628-4B8F-A2F6-FECD79B78354", "someValue" : "bar" }
{ "_id" : "90A26C2A-4976-4EDD-850D-2ED8BEA46F9E",
"collectionB" : [
{
"some" : "foo",
"andOther" : "stuff"
},
{
"some" : "bar",
"andOther" : "random"
}
],
"someValue" : "foo"
}
Sadly mapreduce can't produce full documents.
https://jira.mongodb.org/browse/SERVER-2517
No idea why despite all the attention, whining and upvotes they haven't changed it. So you'll have to do this manually in the language of your choice.
Hopefully you've indexed 'collectionAID' which should improve the speed of your queries. Just write something that goes through your A collection one document at a time, loading the _id and then adding the array from Collection B.
There is a much faster way than https://stackoverflow.com/a/22676205/1578508
You can do it the other way round and run through the collection you want to insert your documents in. (Far less executions!)
db.collA.find().forEach(function (x) {
var collBs = db.collB.find({"collectionAID":x._id},{"_id":0,"collectionA":0});
x.collectionB = collBs.toArray();
db.collA.save(x);
})
What I'm trying to do is pretty straightforward, but I can't find out how to give one field the value of another.
I simply want to update one field with the character count of another.
db.collection.update({$exists:true},{$set : {field1 : field2.length}})
I've tried giving it dot notation
db.collection.update({$exits:true},{$set : {field1: "this.field2.length"}})
As well as using javascript syntax
db.collection.update({$exits:true},
{$set : {field1: {$where : "this.field2.length"}})
But just copied the string and got a "notOkforstorage" respectively. Any help?
Update:
I only get the "notOkforStorage" when I query by ID:
db.collection.update({_id:ObjectID("38289842bbb")},
{$set : {field1: {$where :"this.field2.length"}}})
Try the following code:
db.collection.find(your_querry).forEach(function(doc) {
doc.field1 = doc.field2.length;
db.collection.save(doc);
});
You can use your_querry to select only part of the original collection do perform an update. If you want to process an entire collection, use your_querry = {}.
If you want all operations to be atomic, use update instead of save:
db.collection.find( your_querry, { field2: 1 } ).forEach(function(doc) {
db.collection.update({ _id: doc._id },{ $set: { field1: doc.field2.length } } );
});
Starting Mongo 4.2, db.collection.update() can accept an aggregation pipeline, finally allowing the update/creation of a field based on another field:
// { "_id" : ObjectId("5e84c..."), "field1" : 12, "field2" : "world" }
db.collection.update(
{ "_id" : ObjectId("5e84c...") },
[{ $set: { field1: { $strLenCP: "$field2" } } }]
)
// { "_id" : ObjectId("5e84c..."), "field1" : 5, "field2" : "world" }
The first part {} is the match query, filtering which documents to update.
The second part [{ $set: { field1: { $strLenCP: "$field2" } } }] is the update aggregation pipeline (note the squared brackets signifying the use of an aggregation pipeline). $set is a new aggregation operator and an alias for $addFields. Any aggregation operator can be used within the $set stage; in our case $strLenCP which provides the length of field2.
As far I know the easiest way is the read and write aproach:
//At first, get/prepare your new value:
var d= db.yourColl.fetchOne({....});
d.field1== d.field2.length;
// then update with your new value
db.yourColl.save(d);
Your are using exists in the wrong way.
Syntax: { field: { $exists: <boolean> } }
You use of $where is also incorrect
Use the $where operator to pass either a string containing a JavaScript expression or a full JavaScript function to the query system
db.myCollection.find( { $where: "this.credits == this.debits" } );
db.myCollection.find( { $where: "obj.credits == obj.debits" } );
db.myCollection.find( { $where: function() { return (this.credits == this.debits) } } );
db.myCollection.find( { $where: function() { return obj.credits == obj.debits; } } );
I think you should use Map-Reduce for what you are trying to do.