We Keep Coding

What is the difference between $and and $all in this particular case?

These two lines of code simply output the same result, so what is the difference between them? I know I know, documentation... But I mean in this context. Thank you for your answers!
db.someData.find({$and: [{genre: {$eq: "action"}}, {genre: {$eq: "thriller"}}]}).pretty()
db.someData.find({genre: {$all: ["action", "thriller"]}}).pretty()
This is the collection in my mongodb database.
{
"_id" : ObjectId("5d19fe6080fc4d046d99d42b"),
"title" : "The Last Student Returns",
"meta" : {
"rating" : 9.5,
"aired" : 2018,
"runtime" : 100
},
"visitors" : 1300000,
"expectedVisitors" : 1550000,
"genre" : [
"thriller",
"drama",
"action"
]
}
{
"_id" : ObjectId("5d19fe6080fc4d046d99d42c"),
"title" : "Teach me if you can",
"meta" : {
"rating" : 8.5,
"aired" : 2014,
"runtime" : 90
},
"visitors" : 590378,
"expectedVisitors" : 500000,
"genre" : [
"action",
"thriller"
]
}
{
"_id" : ObjectId("5d19fe6080fc4d046d99d42d"),
"title" : "Supercharged Teaching",
"meta" : {
"rating" : 9.3,
"aired" : 2016,
"runtime" : 60
},
"visitors" : 370000,
"expectedVisitors" : 1000000,
"genre" : [
"thriller",
"action"
]
}

Interesting that you mentioned documentation since your exact question is actually answered there:
Behavior
Equivalent to $and Operation
The $all is equivalent to an $and operation of the specified values;
i.e. the following statement:
{ tags: { $all: [ "ssl" , "security" ] } }
is equivalent to:
{ $and: [ { tags: "ssl" }, { tags: "security" } ] }
But overall there are many ways to get the same result with mongo just like there are many ways to get the same exact result with JS etc.

MongoDB query using $and and $or

I trying to perform a query using $and and $or in MongoDB. Sadly I've had no luck. I found several similar questions posted here on Stack Overflow, this one came closest.
mongodb queries both with AND and OR
Unfortunately the solution did not work for me. I want to allow user to search by project id or title. I do have code that check if the q variable past in is a valid ObjectId before I include it.
Here is my query:
Project.find({
$and : [
{ $or : [ { title: {$regex : req.body.q} }, { _id: req.body.q } ] },
{ userID: req.session.userID }
]
}).then(project => {
console.log(project);
});
sample document:
{ "_id" : ObjectId("5afb583e8341f161a0c950af"), "title" : "Learn Node.js", "status" : "In Progress", "createdOn" : "2014-06-05 22:39:00.000Z" }
{ "_id" : ObjectId("4fe8736dc27bc8be56947d61"), "title" : "Learn MongoDB", "status" : "In Progress", "createdOn" : "2014-06-05 22:39:00.000Z" }
What am I missing?

Apply an expression to each array element in document

I've got a sample document that I'm trying to project within a MongoDB aggregate pipeline. I'm testing with a single document that looks roughly like this:
{
"_id" : "",
"title" : "Questions",
"sortIndex" : 0,
"topics" : [
{
"_id" : "",
"title" : "Creating a Question",
"sortIndex" : 1,
"thumbnail" : "CreatingAQuestion.jpg",
"seenBy" : [ "user101", "user202" ],
"pages" : [
{
"visual" : "SelectPlanets.gif",
"text" : "Some Markdown"
}
]
},
{
"_id" : "",
"title" : "Deleting a Question",
"sortIndex" : 0,
"thumbnail" : "DeletingAQuestion.jpg",
"seenBy" : [ "user101" ],
"pages" : [
{
"visual" : "SelectCard.gif",
"text" : "Some Markdown"
}
]
}
]
}
The output I'm trying to obtain is something along these lines:
{
"_id" : "",
"title" : "Questions",
"topics" : [
{
"title" : "Creating a Question",
"thumbnail" : "CreatingAQuestion.jpg",
"seen" : true
},
{
"title" : "Deleting a Question",
"thumbnail" : "DeletingAQuestion.jpg",
"seen" : false
}
]
}
Specifically the bit I'm struggling with is the seen flag.
I've read the docs which state:
When projecting or adding/resetting a field within an embedded document...
... Or you can nest the fields:
contact: { address: { country: <1 or 0 or expression> } }
I wish to use an expression and I took note of the following:
When nesting the fields, you cannot use dot notation inside the embedded document to specify the field, e.g. contact: { "address.country": <1 or 0 or expression> } is invalid.
So I'm trying to work out how to "reference" a subdocument field within an expression. That quote suggests I can't use dot notation but when I can't seem to get it working with nested notation either. Here's what I've got so far:
db
.getCollection('chapters')
.aggregate([
{
$project: {
title: 1,
topics: {
title: 1,
thumbnail: 1,
publishedAt: 1,
test: "$seenBy",
seen: { $in: ["user202", "$seenBy"] },
}
}
}
])
So I've hard coded user202 into my query for now, and expected to see true and false for the 2 documents. I've also put in a test field to map out the seenBy field from the sub-document. What this produces is:
{
"_id" : "",
"title" : "Questions",
"topics" : [
{
"title" : "Creating a Question",
"thumbnail" : "CreatingAQuestion.jpg",
"test" : [
"user101",
"user202"
],
"seen" : true
},
{
"title" : "Deleting a Question",
"thumbnail" : "DeletingAQuestion.jpg",
"test" : [
"user101",
"user202"
],
"seen" : true
}
]
}
So obviously my "$seenBy" isn't accessing the correct topic because the test field contains the data from the 1st document.
So ultimately my question is, how can I access the seenBy field within a subdocument, referring to the current subdocument so I can create an expression?
Note: I have got this working with multiple $project and an $unwind but wanted to try compress/clean it up a bit.

You really need to use $map here. Simply notating the array in projection ( which is a bit of a boon since MongoDB 3.2 ) does not really cut it when you need a localized value for the current element. That is what you need and it's what $map provides:
db.getCollection('chapters').aggregate([
{ $project: {
title: 1,
topics: {
$map: {
input: "$topics",
as: "t",
in: {
title: "$$t.title",
thumbnail: "$$t.thumbnail",
publishedAt: "$$t.publishedAt",
test: "$$t.seenBy",
seen: { $in: ["user202", "$$t.seenBy"] },
}
}
}}
])
So for each element the current value of "seenBy" as a property is being tested by the expression. Without the $map that is not possible, and you can only really notate the "whole" array. Which is really not what you want to test here.

Meteor Mongodb count fields in nested object

I am trying to create a dashboard where I show summaries of order data within the app. In this case I am simply wanting count the number of items in a given category in my Orders collection. My code so far looks like this:
Collection data
{
"_id" : "a6wHiXxyM5DwSAsfq",
"orderNumber" : 1234,
"createdAt" : "11/01/2016, 14:43:49",
"productsInOrder" : [
{
"category" : "ambient",
"item" : 50818,
"desc" : "Tasty Rubber Chicken",
"quantity" : "44",
"price" : "0.92",
"lineprice" : "40.48",
"_id" : "FFNxG8vujs6NGN69r"
},
{
"category" : "frozen",
"item" : 71390,
"desc" : "Generic Granite Fish",
"quantity" : "11",
"price" : "1.00",
"lineprice" : "11.00",
"_id" : "LcRtpyLxkWyh39kkB"
}
]
}
{
"_id" : "PdpywXCvfew7qojmA",
"orderNumber" : 1234,
"createdAt" : "11/01/2016, 14:44:15",
"productsInOrder" : [
{
"category" : "frozen",
"item" : 71390,
"desc" : "Generic Granite Fish",
"quantity" : "44",
"price" : "1.00",
"lineprice" : "44.00",
"_id" : "dAscx4R8pcBgbzoZs"
},
{
"category" : "frozen",
"item" : 66940,
"desc" : "Gorgeous Granite Bike",
"quantity" : "55",
"price" : "4.21",
"lineprice" : "231.55",
"_id" : "xm3mFRmPmmdPxjfP9"
},
{
"category" : "frozen",
"item" : 96029,
"desc" : "Gorgeous Plastic Fish",
"quantity" : "1234",
"price" : "4.39",
"lineprice" : "5417.26",
"_id" : "7u7SHnpTf7PWcrhGA"
}
]
}
{
"_id" : "xcHZ25qwvyDpDJtAZ",
"orderNumber" : 1234,
"createdAt" : "11/01/2016, 14:44:47",
"productsInOrder" : [
{
"category" : "frozen",
"item" : 31104,
"desc" : "Handcrafted Rubber Keyboard",
"quantity" : "11",
"price" : "4.78",
"lineprice" : "52.58",
"_id" : "LMMwbKFEgnCbgCt9c"
},
{
"category" : "frozen",
"item" : 77832,
"desc" : "Practical Rubber Shirt",
"quantity" : "21",
"price" : "0.62",
"lineprice" : "13.02",
"_id" : "63otkkXWGrTJkwEgX"
},
{
"category" : "frozen",
"item" : 66940,
"desc" : "Gorgeous Granite Bike",
"quantity" : "111",
"price" : "4.21",
"lineprice" : "467.31",
"_id" : "rbPSujey8CFeMPjza"
}
]
}
JS
So far I have tried:
Orders.find({ 'productsInOrder': ['ambient']}).count();
Orders.find({ productsInOrder: { category: 'ambient' }}).count();
Orders.find({ productsInOrder: { $all: [ 'frozen' ] }}).count();
I am having a hard time understanding Mongo queries when the data is nested in this manner. Please can you help point me in the right direction? Many thanks in advance.
* SOLUTION *
I have accomplished the desired result thanks to the contributions below. To make this work I created a method on the server as the query cannot be run on the client using an existing collection. This is done as follows:
Meteor.methods({
'byCategory': function() {
var result = Orders.aggregate([
{ "$unwind": "$productsInOrder" },
{
"$group": {
"_id": null,
"ambient_count": {
"$sum": {
"$cond": [ { "$eq": [ "$productsInOrder.category", "ambient" ] }, 1, 0 ]
}
},
"frozen_count": {
"$sum": {
"$cond": [ { "$eq": [ "$productsInOrder.category", "frozen" ] }, 1, 0 ]
}
},
"other_category_count": {
"$sum": {
"$cond": [ { "$eq": [ "$productsInOrder.category", "other_category" ] }, 1, 0 ]
}
}
}
}
]);
return result;
}
})
and then on the client:
Meteor.call('byCategory', function( error, result ) {
if( error ) {
console.log( error.reason );
} else {
console.log( result[0].ambient_count );
console.log( result[0].frozen_count );
etc....
}
});
Thanks and credit to #chridam and #Brett.

An alternative approach is to use the aggregation framework. Consider the following aggregation pipeline which as the first stage of the aggregation pipeline, the $unwind operator denormalizes the productsInOrder array to output for each input document, n documents where n is the number of array elements. The next pipeline stage has the $group operator which groups all the documents into a single document and stores the counts for each category with the help of the $sum and $cond operators.
In Meteor, you can then use meteorhacks:aggregate package to implement the aggregation:
Add to your app with
meteor add meteorhacks:aggregate
Note, this only works on server side and there is no oberserving support or reactivity built in. Then simply use .aggregate function like below.
var coll = new Mongo.Collection('orders');
var pipeline = [
{ "$unwind": "$productsInOrder" },
{
"$group": {
"_id": null,
"ambient_count": {
"$sum": {
"$cond": [ { "$eq": [ "$productsInOrder.category", "ambient" ] }, 1, 0 ]
}
},
"frozen_count": {
"$sum": {
"$cond": [ { "$eq": [ "$productsInOrder.category", "frozen" ] }, 1, 0 ]
}
},
"other_category_count": {
"$sum": {
"$cond": [ { "$eq": [ "$productsInOrder.category", "other_category" ] }, 1, 0 ]
}
}
}
}
];
var result = coll.aggregate(pipeline);
Running the same pipeline in mongo shell using the sample data will yield:
{
"result" : [
{
"_id" : null,
"ambient_count" : 1,
"frozen_count" : 7,
"other_category_count" : 0
}
],
"ok" : 1
}
You can access the native mongo collection and publish the aggregation results to the orders collection on the client side:
Meteor.publish('categoryCounts', function() {
var self = this,
db = MongoInternals.defaultRemoteCollectionDriver().mongo.db;
orders = db.collection("orders").aggregate(pipeline, // Need to wrap the callback so it gets called in a Fiber.
Meteor.bindEnvironment(
function(err, result) {
// Add each of the results to the subscription.
_.each(result, function(e) {
self.added("orders", e._id, e);
});
self.ready();
},
function(error) {
Meteor._debug( "Error doing aggregation: " + error);
}
)
);
});

If you don't want to do this within Meteor, you will need to use mongo aggregation. Minimongo doesn't include aggregation though, so you will need this package to accomplish it:
https://docs.mongodb.org/manual/core/aggregation-introduction/
I only tested this in mongo itself, so you will have to adapt it to the way that the aggregation package does it:
db.orders.aggregate([
{
$unwind: "$productsInOrder"
},
{
$match: {
"productsInOrder.category": "frozen"
}
},
{
$group: {
_id: null,
count: {
$sum: 1
}
}
}
]);
The first part is unwinding the collection. It will basically make an "order" entry for every instance of $productsInOrder. Once you have the array flattened out, we match on the category you care about; in this case, the "frozen" category. Next we group it up so we can count the number of documents returned. $group is simply constructing the final object that will be output from the query. You can modify this to be whatever you want, or you could group by productsInOrder.category and not even $match on "frozen".

How to delete deep array in mongodb?

I am trying to delete "virtualNumber" : "12345" in the following document:
{
"_id" : ObjectId("50a9db5bdc7a04df06000005"),
"billingInfo" : null,
"date" : "dsfdsfsdfsd",
"description" : "sdfsdff",
"pbx" : {
"_id" : ObjectId("50a9db5bdc7a04df06000006"),
"did" : {
"1234567890" : {
"inventoryId" : "509df7547e84b25e18000001",
"didcountry" : "india",
"didState" : "bangalore",
"routeType" : "CallForward",
"didNumber" : "1234567890",
"didVirtualNumbers" : [
{
"virtualNumber" : "12345"
},
{
"virtualNumber" : "56789"
}
],
"id" : ObjectId("50a9db9acdfb4f9217000002")
}
},
},
I am using node.js, so I constructed a query in JavaScript:
var query = {_id: ObjectId("50a9db5bdc7a04df06000005")};
var obj = {};
obj["pbx.did.1234567890.didVirtualNumbers.virtualNumber"]=12345;
//problem
collection.update(query,{$pull:obj});

You need to match the array element like:
{"$pull": {"pbx.did.7259591220.didVirtualNumbers": {"virtualNumber": "12345"}}}
So you should change your code to:
obj["pbx.did.7259591220.didVirtualNumbers"]={"virtualNumber": "12345"};

Please refer to http://www.mongodb.org/display/DOCS/Updating#Updating-%24pull
It mentions the pull field should be an array.