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Validate that an attribute's value matches a regular expression using format and the with option. class User < ApplicationRecord validates :name, format: { with: /\A\w{6,10}\z/ } end You can also define a constant and set its value to a regular expression and pass it to the with: option. ...

You can check if a value is included in an array using the inclusion: helper. The :in option and its alias, :within show the set of acceptable values. class Country < ApplicationRecord validates :continent, inclusion: { in: %w(Africa Antartica Asia Australia ...

Add the [Serializable] attribute to mark an entire object for binary serialization: [Serializable] public class Vector { public int X; public int Y; public int Z; [NonSerialized] public decimal DontSerializeThis; [OptionalField] public string Name; } All...

If you use the [NonSerialized] attribute, then that member will always have its default value after deserialization (ex. 0 for an int, null for string, false for a bool, etc.), regardless of any initialization done in the object itself (constructors, declarations, etc.). To compensate, the attribut...

That would get more control over serialization, how to save and load types Implement ISerializable interface and create an empty constructor to compile [Serializable] public class Item : ISerializable { private string _name; public string Name { get { return _name; } ...

Implements a serialization surrogate selector that allows one object to perform serialization and deserialization of another As well allows to properly serialize or deserialize a class that is not itself serializable Implement ISerializationSurrogate interface public class ItemSurrogate : ISerial...

The first element of sys.argv[0] is the name of the python file being executed. The remaining elements are the script arguments. # script.py import sys print(sys.argv[0]) print(sys.argv) $ python script.py => script.py => ['script.py'] $ python script.py fizz => script.py ...

You can install NLTK over pip (pip install nltk).After it is installed, many components will not be present, and you will not be able to use some of NLTK's features. From your Python shell, run the function ntlk.download() to select which additional packages you want to install using UI. Alternati...

In order to sort a query, instead of using findAll(), you should use findAllSorted(). RealmResults<SomeObject> results = realm.where(SomeObject.class) .findAllSorted("sortField", Sort.ASCENDING); Note: sort() returns a completely new ...

This example goes over how to set up CoreNLP from the latest official release. This example will take you through downloading the package, and running a simple command-line invocation of CoreNLP. Prerequisites: Java JVM 8. The command java -version should complete successfully with a line like: ...

In order to dynamically decide what beans to inject, we can use FactoryBeans. These are classes which implement the factory method pattern, providing instances of beans for the container. They are recognized by Spring and can be used transparently, without need to know that the bean comes from a fac...

When referring to gcc's documentation, you should know which version of gcc you are running. The GCC project has a manual for each version of gcc which includes features that are implemented in that version. Use the '-v' option to determine the version of gcc you are running. gcc -v Example Ou...

Problem In a similar way that SQL injection allows an attacker to execute arbitrary queries on a database, command-line injection allows someone to run untrusted system commands on a web server. With an improperly secured server this would give an attacker complete control over a system. Let's sa...

Sometimes you want to have a file held in Git but ignore subsequent changes. Tell Git to ignore changes to a file or directory using update-index: git update-index --assume-unchanged my-file.txt The above command instructs Git to assume my-file.txt hasn't been changed, and not to check or repor...

Starting the Erlang shell On a UNIX system you start the Erlang shell from a command prompt with the command erl Example: $ erl Erlang/OTP 18 [erts-7.0] [source] [64-bit] [smp:8:8] [async-threads:10] [hipe] [kernel-poll:false] Eshell V7.0 (abort with ^G) 1> The text that shows when y...

Environment variables that affect the go tool can be viewed via the go env [var ...] command: $ go env GOARCH="amd64" GOBIN="/home/yourname/bin" GOEXE="" GOHOSTARCH="amd64" GOHOSTOS="linux" GOOS="linux" GOPATH="/home/yourname&q...

If Go is not pre-installed in your system you can go to https://golang.org/dl/ and choose your platform to download and install Go. To set up a basic Go development environment, only a few of the many environment variables that affect the behavior of the go tool (See: Listing Go Environment Variabl...

A deadlock is what occurs when two or more threads are waiting for eachother to complete or to release a resource in such a way that they wait forever. A typical scenario of two threads waiting on eachother to complete is when a Windows Forms GUI thread waits for a worker thread and the worker thre...

A deadlock is what occurs when two or more threads are waiting for eachother to complete or to release a resource in such a way that they wait forever. If thread1 holds a lock on resource A and is waiting for resource B to be released while thread2 holds resource B and is waiting for resource A to ...

This is a nice trick to add a link to code, so it will be easy to jump to the code that issued the log. With the following code, this call: MyLogger.logWithLink("MyTag","param="+param); Will result in: 07-26...012/com.myapp D/MyTag: MyFrag:onStart(param=3) (MyFrag.java:236...