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Showing posts from January, 2020

Aggregate/project Sub-document As Top-level Document In Mongo

Answer : When you have many, many fields in the sub-document and occasionally it is updated with new fields, then projection is not a viable option. Fortunately, since 3.4, MongoDB has a new operator called $replaceRoot . All you have to do is add a new stage at the end of your pipeline. db.getCollection('sample').aggregate([ { $replaceRoot: {newRoot: "$command"} }, { $project: {score: 0 } //exclude score field } ]) This would give you the desired output. Note that in case of aggregation (especially after a $group stage) the 'command' document could be an array and could contain multiple documents. In this case you need to $unwind the array first to be able to use $replaceRoot . As you have guessed, $project allows you to do that: db.col.aggregate([ { $project : { _id: "$command._id", name: "$command.name", strike: "$command.strike", duratio

% Associative Array Key In Php Code Example

Example 1: how to create an associative array in php <?php $associativeArray = [ "carOne" => "BMW" , "carTwo" => "VW" , "carThree" => "Mercedes" ] ; echo $associativeArray [ "carTwo" ] . " Is a german brand" ; ?> Example 2: associative array php // Associative Array in PHP /******** ARRAY TYPES ************************************************ There are basically 03 Types of array in php 1. Indexed arrays => Arrays with a numeric index 2. Associative arrays => Arrays with named keys 3. Multidimensional arrays => Arrays containing one or more arrays ***********************************************************************/ //EXAMPLE //This is the second one - Associative arrays $age = array ( "Peter" => "35" , "Naveen" => "37" , "Amit" => &

Android Based On Which Language Code Example

Example: what language is android written in Java, C, xml, Python

Close Bootstrap Modal Jquery Code Example

Example 1: close modal jquery $('#myModal').modal('toggle'); $('#myModal').modal('show'); $('#myModal').modal('hide'); Example 2: on modal close jquery $('#myModal').on('hidden.bs.modal', function () { // do something… }) Example 3: jquery close bootstrap model $('#modal').modal('hide'); Example 4: data-dismiss= modal in jquery $(document).ready(function(){ // Open modal on page load $("#myModal").modal('show'); // Close modal on button click $(".btn").click(function(){ $("#myModal").modal('hide'); }); }); Example 5: close bootstrap modal with javascript $('#myModal').modal('hide'); Example 6: bootstrap modal prevent close $('#myModal').modal({backdrop: 'static', keyboard: false})

8 Oz To Grams Code Example

Example: oz to g 1 ounce (oz) = 28.3495231 grams (g)

Topological Sorting Gfg Code Example

Example: topological sort cp algorithms int n ; // number of vertices vector < vector < int >> adj ; // adjacency list of graph vector < bool > visited ; vector < int > ans ; void dfs ( int v ) { visited [ v ] = true ; for ( int u : adj [ v ] ) { if ( ! visited [ u ] ) dfs ( u ) ; } ans . push_back ( v ) ; } void topological_sort ( ) { visited . assign ( n , false ) ; ans . clear ( ) ; for ( int i = 0 ; i < n ; ++ i ) { if ( ! visited [ i ] ) dfs ( i ) ; } reverse ( ans . begin ( ) , ans . end ( ) ) ; }

Ansible Exclude A Host Code Example

Example: ansible exclude a host # By using the '!' you exclude a host from a play. ansible-playbook --limit 'myapp:!database3' myplay.yaml

Can We Overload The Main Method In Java?

Answer : You can overload the main() method, but only public static void main(String[] args) will be used when your class is launched by the JVM. For example: public class Test { public static void main(String[] args) { System.out.println("main(String[] args)"); } public static void main(String arg1) { System.out.println("main(String arg1)"); } public static void main(String arg1, String arg2) { System.out.println("main(String arg1, String arg2)"); } } That will always print main(String[] args) when you run java Test ... from the command line, even if you specify one or two command-line arguments. You can call the main() method yourself from code, of course - at which point the normal overloading rules will be applied. EDIT: Note that you can use a varargs signature, as that's equivalent from a JVM standpoint: public static void main(String... args) Yes, you can overload main method

Bootstrap Icon Cdn Link Code Example

Example 1: bootstrap icons cdn < link rel = " stylesheet " href = " https://cdnjs.cloudflare.com/ajax/libs/bootstrap-icons/1.4.1/bootstrap-icons.svg " > Example 2: bootstrap icons cdn Cannot GET /

ActiveModel Serializer - Passing Params To Serializers

Answer : AMS version: 0.10.6 Any options passed to render that are not reserved for the adapter are available in the serializer as instance_options . In your controller: def index @watchlists = Watchlist.belongs_to_user(current_user) render json: @watchlists, each_serializer: WatchlistOnlySerializer, currency: params[:currency] end Then you can access it in the serializer like so: def market_value # this is where I'm trying to pass the parameter Balance.watchlist_market_value(self.id, instance_options[:currency]) end Doc: Passing Arbitrary Options To A Serializer AMS version: 0.9.7 Unfortunately for this version of AMS, there is no clear way of sending parameters to the serializer. But you can hack this using any of the keywords like :scope (as Jagdeep said) or :context out of the following accessors: attr_accessor :object, :scope, :root, :meta_key, :meta, :key_format, :context, :polymorphic Though I would prefer :context over :scope for the p

A Module That Has A Basis Shorter Than Its Rank?

Answer : This is actually proven in Dummit and Foote. To distinguish the two definitions of rank, call the maximum number of elements of M M M which are linearly independent the LI rank , and for a free R R R -module M M M call the size of a basis of M M M the free rank . As you observe, since a basis must be linearly independent, then free rank ≤ \leq ≤ LI rank. Proposition 3 of § 12.1 \S12.1 §12.1 of Dummit and Foote (p. 459) implies the reverse inequality. Proposition 3. Let R R R be an integral domain and let M M M be a free R R R -module of rank n < ∞ n < \infty n < ∞ . Then any n + 1 n+1 n + 1 elements of M M M are R R R -linearly dependent, i.e., for any y 1 , … , y n + 1 ∈ M y_1, \ldots, y_{n+1} \in M y 1 ​ , … , y n + 1 ​ ∈ M there are elements r 1 , … , r n + 1 ∈ R r_1, \ldots, r_{n+1} \in R r 1 ​ , … , r n + 1 ​ ∈ R , not all zero, such that r 1 y 1 + ⋯ + r n + 1 y n + 1 = 0   . r_1 y_1 + \cdots + r_{n+1} y_{n+1} = 0 \, . r 1 ​ y 1 ​

A Light Alternative To Gnome-system-monitor?

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Answer : htop it is a terminal app: sudo apt-get install htop htop htop with graph mode ProcMeter3 Look for this system monitor (GUI works with GTK1,2,3): ProcMeter3 An utility which works with LCD devices even. ProcMeter3 GUI on GTK3 Psymon Also once I tried a Psymon . This is not extremely lightweight software and written on Qt (not GTK , and therefore should work better with KDE) though despite to this fact it works well not only with Unity and Gnome, but also in other OS, like FreeBSD, MacOS, Windows etc., because it use great python-psutil Debian package. So look it closer: Nice post about Psymon Psymon project site Psymon You can try xfce4-taskmanager from Xfce or lxtask from LXDE. Neither of them pull any specific dependencies. ndicator-SysMonitor Indicator-SysMonitor does a little, but does it well. Once installed and run, it displays CPU and RAM usage on your top panel. Simple. Download from here Conky One of my personal favourites

Array Pop Push Javascript Code Example

Example 1: how to push items in array in javascript let items = [ 1 , 2 , 3 ] items . push ( 4 ) ; // items = [1, 2, 3, 4] Example 2: javascript pop var cars = [ 'mazda' , 'honda' , 'tesla' ] ; var telsa = cars . pop ( ) ; //cars is now just mazda,honda

Anxiety Po Polsku Code Example

Example: anxiety Cold Shower

AWS DotNet SDK Error: Unable To Get IAM Security Credentials From EC2 Instance Metadata Service

Answer : I had the same issue, here is how I fixed it on my development environment I created an AWS profile using the AWS extension for Visual studio Once the profile is set up the credentials are passed using the profile and it worked fine for me Point to note here, the user profile accessing the key manager should have a valid security group assigned for the Secrets manager. Try it out let me know, how it went. Same issue and resolved by deleting $HOME/.aws/config and credentials files and recreating with AWS CLI. In my case I was switching laptops from Windows to a new MBP. I had setup my new environment by copying the .aws directory files and confirmed that AWS CLI worked correctly. Confusingly the dotnet SDK failed with same errors.

Add Elements Into Array List Java Code Example

Example: how to add to an arraylist java import java . util . ArrayList ; public class Details { public static void main ( String [ ] args ) { //ArrayList<String> Declaration ArrayList < String > al = new ArrayList < String > ( ) ; //add method for String ArrayList al . add ( "Ram" ) ; al . add ( "Shyam" ) ; al . add ( "CPS" ) ; al . add ( "John" ) ; al . add ( "Steve" ) ; System . out . println ( "Elements of ArrayList of String Type: " + al ) ;

Apache Web Server Stopped Xampp Ubuntu Code Example

Example: apache server not starting in xampp ubuntu sudo /etc/init.d/apache2 stop sudo /opt/lampp/lampp start