What framework are you using? This is not MongoDB shell and looks like some weird wrapper around [MapReduce][1]. In that case [$unwind][2] would not be available, and you need it for user in the [aggregation framework][3]. Here&#39;s what you want in the mongo shell:

    db.articles.aggregate([
      {$match: { class_date: { $gte: date } } },
      {$project: { _id: 0, class_artist: 1 } },
      {$unwind: &quot;$class_artist&quot; },
      {$group: { _id: &quot;$class_artist&quot;, tags: { $sum: 1 } }},
      {$project: { _id: 0,class_artist: &quot;$_id&quot;, tags: 1 } },
      {$sort: { tags: -1 } }
    ])

So efficiently:

1. [Filter][4] by date because you already set a var for the last 7 days
2. [Project][5] only the field(s) we need { We need only one! } 
3. [Unwind][6] the array so we now have a record for every array element in every document
4. [Group][7] on the Artist from the expanded documents
5. Project into a document format you can use as group messed around with _id
6. [Sort][8] the results in reverse order to see the top tagged first

And the great thing about aggregation is you can gradually build up those stages to see what is going on.

Shake and bake into your own driver implmentation or ODM framework as required.


  [1]: http://docs.mongodb.org/manual/core/map-reduce/
  [2]: http://docs.mongodb.org/manual/reference/operator/aggregation/unwind/
  [3]: http://docs.mongodb.org/manual/core/aggregation-pipeline/
  [4]: http://docs.mongodb.org/manual/reference/operator/aggregation/match/
  [5]: http://docs.mongodb.org/manual/reference/operator/aggregation/project/
  [6]: http://docs.mongodb.org/manual/reference/operator/aggregation/unwind/
  [7]: http://docs.mongodb.org/manual/reference/operator/aggregation/group/
  [8]: http://docs.mongodb.org/manual/reference/operator/aggregation/sort/

I&#39;ve often heard of Streams2 and old-streams, but what is Streams3? [It get mentioned in this talk by Thorsten Lorenz](http://youtu.be/9llfAByho98?t=45s).

Where can I read about it, and what is the difference between Streams2 and Streams3.

Doing a search on Google, I also see it mentioned in the [Changelog of Node 0.11.5](http://blog.nodejs.org/2013/08/06/node-v0-11-5-unstable/),

&gt; stream: Simplify flowing, passive data listening (streams3) (isaacs)


What is Streams3 in Node.js and how does it differ from Streams2?

I want to import a library project into my app but whenever I try to do so , Android Studio doesn&#39;t recognise it 

It also gives me errors in build.gradle ..

The Library is : PagerSlidingTabStrip ....

Here are some pictures :

&gt;![enter image description here][1]
&gt;
&gt;![enter image description here][2]



I have been trying to make it work for 3 days so far !!
Please Help Me :)

***EDIT:***

    apply plugin: &#39;android-library&#39;

    dependencies {
    compile &#39;com.android.support:support-v4:19.0.0&#39;
    }

    android {
    compileSdkVersion Integer.parseInt(project.ANDROID_BUILD_SDK_VERSION)
    buildToolsVersion project.ANDROID_BUILD_TOOLS_VERSION

    defaultConfig {
        minSdkVersion 8
        targetSdkVersion Integer.parseInt(project.ANDROID_BUILD_TARGET_SDK_VERSION)
    }

    sourceSets {
        main {
            manifest.srcFile &#39;AndroidManifest.xml&#39;
            java.srcDirs = [&#39;src&#39;]
            res.srcDirs = [&#39;res&#39;]
        }
    }
    }

     apply from: &#39;https://raw.github.com/chrisbanes/gradle-mvn-push/master/gradle-mvn-push.gradle&#39;


***EDIT2 :***

    FAILURE: Build failed with an exception.

    * What went wrong:
    A problem occurred configuring project &#39;:Sahertoday&#39;.
    &gt; Could not resolve all dependencies for configuration &#39;:Sahertoday:_debugCompile&#39;.
    &gt; Could not find com.astuetz:pagerslidingtabstrip:1.0.1.
     Required by:
         Saher-3:Sahertoday:unspecified

    * Try:
     Run with --stacktrace option to get the stack trace. Run with --info or --debug option to get         more log output.

     BUILD FAILED

  [1]: http://i.stack.imgur.com/xAVb5.png
  [2]: http://i.stack.imgur.com/U4SWR.png

Importing Facebook library in Android Studio: Could not find property &#39;ANDROID_BUILD_SDK_VERSION&#39;

I&#39;ve got a list of articles, and each of them has an array property which lists various individuals mentioned in them:

    _id: {
        $oid: &quot;52b632a9e4f2ba13c82ccd23&quot;
    },
    providerName: &quot;The Guardian&quot;,
    url: &quot;http://feeds.theguardian.com/c/34708/f/663860/s/3516cebc/sc/38/l/0L0Stheguardian0N0Cmusic0C20A130Cdec0C220Cwaterboys0Efishermans0Eblues0Etour0Ehammersmith/story01.htm&quot;,
    subject: &quot;The Waterboys – review&quot;,
    class_artist: [
        &quot;paul mccartney&quot;
    ]

I&#39;ve been trying (unsuccessfully) to get a list of all the individual artists (`class_artist`), based on the number of articles they&#39;ve been tagged in within the past 7 days.

I&#39;ve gotten as far as:

    var date = new Date();
    date.setDate(date.getDate() - 7);
    
    db.articles.group({
        key: { class_artist: 1 },
        cond: { class_date: { $gt: date } },
        reduce: function ( curr, result ) { result.cnt++; },
        initial: { cnt : 0 }
    }).sort({cnt: -1});

But unfortunately, it doesn&#39;t count them based on the individual array values, but by array compositions (that is, lists of artists).

I tried using the `$unwind` function, but have not been able to make it work.

MongoDB group by array inner-elements

I've got a list of articles, and each of them has an array property which lists various individuals mentioned in them:
<pre><code class="hljs language-vbnet">_id: {
 $oid: "52b632a9e4f2ba13c82ccd23"
},
providerName: "The Guardian",
url: "http://feeds.theguardian.com/c/34708/f/663860/s/3516cebc/sc/38/l/0L0Stheguardian0N0Cmusic0C20A130Cdec0C220Cwaterboys0Efishermans0Eblues0Etour0Ehammersmith/story01.htm",
subject: "The Waterboys – review",
class_artist: [
 "paul mccartney"
]
</code></pre>
I've been trying (unsuccessfully) to get a list of all the individual artists (<code>class_artist</code>), based on the number of articles they've been tagged in within the past 7 days.
I've gotten as far as:
<pre><code class="hljs language-css">var date = new Date();
date.setDate(date.getDate() - 7);

db.articles.group({
 key: { class_artist: 1 },
 cond: { class_date: { $gt: date } },
 reduce: function ( curr, result ) { result.cnt++; },
 initial: { cnt : 0 }
}).sort({cnt: -1});
</code></pre>
But unfortunately, it doesn't count them based on the individual array values, but by array compositions (that is, lists of artists).
I tried using the <code>$unwind</code> function, but have not been able to make it work.

I am interested in optimizing a &quot;pagination&quot; solution I&#39;m working on with MongoDB. My problem is straight forward. I usually limit the number of documents returned using the `limit()` functionality. This forces me to issue a redundant query without the `limit()` function in order for me to also capture the total number of documents in the query so I can pass to that to the client letting them know they&#39;ll have to issue an additional request(s) to retrieve the rest of the documents.

Is there a way to condense this into 1 query? Get the total number of documents but at the same time only retrieve a subset using `limit()`? Is there a different way to think about this problem than I am approaching it?

Get a count of total documents with MongoDB when using limit

I have the following schema with mongoose:

    var SimSchema = new Schema({
        msisdn     : { type : String , unique : true, required : true },
        imsi       : { type : String , unique : true, required : true },
        status     : { type : Boolean, default: true},
        signal     : { type : Number },
        probe_name : { type:  String , required : true }
    });

I have `unique`option for the `msisdn` and `imsi`.

In some cases this condition is well respected. 
For the following `mocha` test:

    &quot;use strict&quot;;
    
    var app      = require(&#39;../../app&#39;);
    var http     = require(&#39;http&#39;);
    var request  = require(&#39;supertest&#39;);
    var mongoose = require(&#39;mongoose&#39;);
    var should   = require(&#39;should&#39;);
    
    
    
    describe(&#39;[ Sim controller ] &#39;, function(){
      before(function(done) {
        app.set_env(&#39;test&#39;);
        this.server = app.start(function() {
          mongoose.connection.db.dropDatabase(function() {
            done();
          })
        });
      });
    
    
      beforeEach(function(done){
        done();
      });
    
    
      it(&#39;Sim with good parameters should be created in the database&#39;, function(done){
        var newSim = {
          msisdn:     &#39;1234&#39;,
          imsi:       &#39;007&#39;,
          probe_name: &#39;BOUCHON_1&#39;
        };
    
        request(this.server)
          .post(&#39;/sims&#39;)
          .set(&#39;Content-Type&#39;, &#39;application/json&#39;)
          .send(newSim)
          .expect(200).end(function(err, res) {
            if (err) return done(err);
            res.body.should.have.property(&#39;imsi&#39;);
            res.body.should.have.property(&#39;probe_name&#39;);
            res.body.should.have.property(&#39;msisdn&#39;);
            setTimeout(function() {
              done();
            }, 1000);
          });
      });
    
    
      it(&#39;Sim imsi/msisdn is unique in the database&#39;, function(done){
        var newSim = {
          msisdn:     &#39;1234&#39;,
          imsi:       &#39;007&#39;,
          probe_name: &#39;BOUCHON_1&#39;
        };
    
        request(this.server)
          .post(&#39;/sims&#39;)
          .set(&#39;Content-Type&#39;, &#39;application/json&#39;)
          .send(newSim)
          .expect(200).end(function(err, res) {
            if (err) return done(err);
            res.body.should.have.property(&#39;error&#39;).equal(&#39;Duplicate Item&#39;);
            done();
          });
      });
    
    
      after(function(done) {
        app.stop(done);
      });
    });

It&#39;s working fine if I run it directly: 

    julio$ mocha test/controllers/ctrl_sim.js 

But If I run it thanks to the recessive option it failed:

      1) [ Sim controller ]  Sim imsi/msisdn is unique in the database:
         Uncaught AssertionError: expected { __v: 0,
      imsi: &#39;007&#39;,
      msisdn: &#39;1234&#39;,
      probe_name: &#39;BOUCHON_1&#39;,
      _id: &#39;530a2b7f52273aa90783baf0&#39;,
      status: true } to have property &#39;error&#39;

I read on stack that sometimes the `unique` condition is not well respected as the index is not refreshed.
Do you think this is my case? In fact, I delete the database for each mocha test suite. Maybe mongo doesn&#39;t have the time to recreate all the indexes each time.

Any idea?

Mongoose &amp; unique field

I have a collection like this:

    {
        &#39;datetime&#39;: some-date,
        &#39;lat&#39;: &#39;32.00&#39;,
        &#39;lon&#39;: &#39;74.00&#39;
    },
    {
        &#39;datetime&#39;: some-date,
        &#39;lat&#39;: &#39;32.00&#39;,
        &#39;lon&#39;: &#39;74.00&#39;
    }

How can I get the latest record from MongoDB, where the datetime is the latest one? I want only a single record.


Get latest MongoDB record by field of datetime

&lt;p&gt; I encountered a strange behavior of mongo and I would like to clarify it a bit...&lt;br&gt;
My request is simple as that: I would like to get a size of single document in collection.
I found two possible solutions:&lt;br&gt; &lt;/p&gt;
+ Object.bsonsize - some javascript method that should return a size in bytes&lt;/li&gt;
&lt;li&gt;db.collection.stats() - where there is a line &#39;avgObjSize&#39; that produce some &quot;aggregated&quot;(average) size view on the data. It simply represents average size of single document.&lt;/li&gt;
&lt;br&gt;
When I create test collection with only one document, both functions returns different values. How is it possible? &lt;br&gt;
Does it exist some other method to get a size of a mongo document?


Here, I provide some code I perform testing on:

1. I created new database &#39;test&#39; and input simple document with only one attribute: type:&quot;auto&quot;

        db.test.insert({type:&quot;auto&quot;})

2. output from stats() function call: *db.test.stats()*:

        { 
          &quot;ns&quot; : &quot;test.test&quot;,
          &quot;count&quot; : 1,
          &quot;size&quot; : 40,
          &quot;avgObjSize&quot; : 40,
          &quot;storageSize&quot; : 4096,
          &quot;numExtents&quot; : 1,
          &quot;nindexes&quot; : 1,
          &quot;lastExtentSize&quot; : 4096,
          &quot;paddingFactor&quot; : 1,
          &quot;systemFlags&quot; : 1,
          &quot;userFlags&quot; : 0,
          &quot;totalIndexSize&quot; : 8176,
          &quot;indexSizes&quot; : {
                &quot;_id_&quot; : 8176
        },
        &quot;ok&quot; : 1
       }

3. output from bsonsize function call: *Object.bsonsize(db.test.find({test:&quot;auto&quot;}))*

        481



How to get the size of single document in Mongodb?

How can I connect Robomongo (or any other mongodb client) to the mongodb instance that is created by my local Meteor application?


How to connect mongodb clients to local Meteor MongoDB

Suppose I have a collection that contains the following documents:

	{ &quot;_id&quot;: 1, name: &quot;Apple&quot; }
	{ &quot;_id&quot;: 2, name: &quot;Banana&quot;, &quot;is_reported&quot;: null }
	{ &quot;_id&quot;: 3, name: &quot;Cherry&quot;, &quot;is_reported&quot;: false }
	{ &quot;_id&quot;: 4, name: &quot;Kiwi&quot;,   &quot;is_reported&quot;: true }

Is there a simpler query to select all documents where &quot;is_reported&quot; is in a falsy state; that is, either non-existent, null, or false?  That is, a query that selects Apple, Banana, and Cherry, but not Kiwi?

[According to the MongoDB FAQ](http://docs.mongodb.org/manual/faq/developers/#faq-developers-query-for-nulls), `{ &quot;is_reported&quot;: null }` will select documents where &quot;is_reported&quot; is either null or nonexistent, but it still doesn&#39;t select documents where &quot;is_reported&quot; is false.

Right now I have the following query, which works fine, but it just doesn&#39;t seem very elegant.  If there are multiple fields that I need to select on, it gets messy very fast.  Is there a better query that achieves the same end result?

	db.fruits.find({ $or: [ { &quot;is_reported&quot;: null }, { &quot;is_reported&quot;: false } ] })

Select MongoDB documents where a field either does not exist, is null, or is false?

2 days old with Mongo and I have a SQL background so bear with me. As with mysql, it is very convenient to be in the MySQL command line and output the results of a query to a file on the machine. I am trying to understand how I can do the same with Mongo, **while being in the shell**

I can easily get the output of a query I want by being outside of the shell and executing the following command:

    mongo localhost:27017/dbname --eval &quot;printjson(db.collectionName.findOne())&quot; &gt; sample.json

The above way is fine, but it requires me to exit the mongo shell or open a new terminal tab to execute this command. It would be very convenient if I could simply do this while still being inside the shell. 

P.S: the Question is an offshoot of a question I posted on [SO][1] 


  [1]: https://stackoverflow.com/questions/22540405/syntax-error-missingl-before-statement-while-outputting-mongodb-query-to-a-text/22541861#22541861

Printing Mongo query output to a file while in the mongo shell

When using MongoDB&#39;s [`$in`][1] clause, does the order of the returned documents always correspond to the order of the array argument?


  [1]: http://docs.mongodb.org/manual/reference/operator/query/in/

Does MongoDB&#39;s $in clause guarantee order

How would I get an array containing all values of a certain field for all of my documents in a collection?

db.collection:

    { &quot;_id&quot; : ObjectId(&quot;51a7dc7b2cacf40b79990be6&quot;), &quot;x&quot; : 1 }
    { &quot;_id&quot; : ObjectId(&quot;51a7dc7b2cacf40b79990be7&quot;), &quot;x&quot; : 2 }
    { &quot;_id&quot; : ObjectId(&quot;51a7dc7b2cacf40b79990be8&quot;), &quot;x&quot; : 3 }
    { &quot;_id&quot; : ObjectId(&quot;51a7dc7b2cacf40b79990be9&quot;), &quot;x&quot; : 4 }
    { &quot;_id&quot; : ObjectId(&quot;51a7dc7b2cacf40b79990bea&quot;), &quot;x&quot; : 5 }

&quot;db.collection.ListAllValuesForfield(x)&quot;
Result: [1,2,3,4,5]

Also, what if this field was an array?

    { &quot;_id&quot; : ObjectId(&quot;51a7dc7b2cacf40b79990be6&quot;), &quot;y&quot; : [1,2] }
    { &quot;_id&quot; : ObjectId(&quot;51a7dc7b2cacf40b79990be7&quot;), &quot;y&quot; : [3,4] }
    { &quot;_id&quot; : ObjectId(&quot;51a7dc7b2cacf40b79990be8&quot;), &quot;y&quot; : [5,6] }
    { &quot;_id&quot; : ObjectId(&quot;51a7dc7b2cacf40b79990be9&quot;), &quot;y&quot; : [1,2] }
    { &quot;_id&quot; : ObjectId(&quot;51a7dc7b2cacf40b79990bea&quot;), &quot;y&quot; : [3,4] }

&quot;db.collection.ListAllValuesInArrayField(y)&quot;
Result: [1,2,3,4,5,6,1,2,3,4]

Additionally, can I make this array unique? [1,2,3,4,5,6]


List all values of a certain field in mongodb

For example, I have these documents:

    {
      &quot;addr&quot;: &quot;address1&quot;,
      &quot;book&quot;: &quot;book1&quot;
    },
    {
      &quot;addr&quot;: &quot;address2&quot;,
      &quot;book&quot;: &quot;book1&quot;
    },
    {
      &quot;addr&quot;: &quot;address1&quot;,
      &quot;book&quot;: &quot;book5&quot;
    },
    {
      &quot;addr&quot;: &quot;address3&quot;,
      &quot;book&quot;: &quot;book9&quot;
    },
    {
      &quot;addr&quot;: &quot;address2&quot;,
      &quot;book&quot;: &quot;book5&quot;
    },
    {
      &quot;addr&quot;: &quot;address2&quot;,
      &quot;book&quot;: &quot;book1&quot;
    },
    {
      &quot;addr&quot;: &quot;address1&quot;,
      &quot;book&quot;: &quot;book1&quot;
    },
    {
      &quot;addr&quot;: &quot;address15&quot;,
      &quot;book&quot;: &quot;book1&quot;
    },
    {
      &quot;addr&quot;: &quot;address9&quot;,
      &quot;book&quot;: &quot;book99&quot;
    },
    {
      &quot;addr&quot;: &quot;address90&quot;,
      &quot;book&quot;: &quot;book33&quot;
    },
    {
      &quot;addr&quot;: &quot;address4&quot;,
      &quot;book&quot;: &quot;book3&quot;
    },
    {
      &quot;addr&quot;: &quot;address5&quot;,
      &quot;book&quot;: &quot;book1&quot;
    },
    {
      &quot;addr&quot;: &quot;address77&quot;,
      &quot;book&quot;: &quot;book11&quot;
    },
    {
      &quot;addr&quot;: &quot;address1&quot;,
      &quot;book&quot;: &quot;book1&quot;
    }

and so on.&lt;br&gt;&lt;br&gt;&lt;br&gt;How can I make a request, which will describe the top N addresses and the top M books per address?&lt;br&gt;&lt;br&gt;Example of expected result:&lt;br&gt;&lt;br&gt; address1 | book_1: 5&lt;br&gt;          | book_2: 10&lt;br&gt;          | book_3: 50&lt;br&gt;          | total: 65&lt;br&gt; ______________________&lt;br&gt; address2 | book_1: 10&lt;br&gt;          | book_2: 10&lt;br&gt;          |...&lt;br&gt;          | book_M: 10&lt;br&gt;          | total: M*10&lt;br&gt;...&lt;br&gt; ______________________&lt;br&gt; addressN | book_1: 20&lt;br&gt;          | book_2: 20&lt;br&gt;          |...&lt;br&gt;          | book_M: 20&lt;br&gt;          | total: M*20

mongodb group values by multiple fields

I am playing around with MongoDB trying to figure out how to do a simple

    SELECT province, COUNT(*) FROM contest GROUP BY province

But I can&#39;t seem to figure it out using the aggregate function. I can do it using some really weird group syntax

    db.user.group({
        &quot;key&quot;: {
            &quot;province&quot;: true
        },
        &quot;initial&quot;: {
            &quot;count&quot;: 0
        },
        &quot;reduce&quot;: function(obj, prev) {
            if (true != null) if (true instanceof Array) prev.count += true.length;
            else prev.count++;
        }
    });

But is there an easier/faster way using the aggregate function?

MongoDB SELECT COUNT GROUP BY

Is it possible to rename the name of fields returned in a find query? I would like to use something like `$rename`, however I wouldn&#39;t like to change the documents I&#39;m accessing. I want just to retrieve them differently, something that works like `SELECT COORINATES AS COORDS` in SQL.
 
What I do now:

    db.tweets.findOne({}, {&#39;level1.level2.coordinates&#39;: 1, _id:0})
    {&#39;level1&#39;: {&#39;level2&#39;: {&#39;coordinates&#39;: [10, 20]}}}

What I would like to be returned is:
`{&#39;coords&#39;: [10, 20]}`

Content Type	Original Author	Original Content on Stackoverflow
Question	Gil Adirim	View Question on Stackoverflow
Solution 1 - Mongodb	Neil Lunn	View Answer on Stackoverflow

MongoDB group by array inner-elements

Mongodb Problem Overview

Mongodb Solutions

Solution 1 - Mongodb

Importing Facebook library in Android Studio: Could not find property 'ANDROID_BUILD_SDK_VERSION'

What is Streams3 in Node.js and how does it differ from Streams2?

Attributions