🖊️
Today I Learned
  • Home(ish) for Things I've Learned
  • 🦄General
    • Agile Development
      • Tips for dealing with Humans
      • Definition of Done (DOD)
      • Inclusiveness
      • OKRs
      • Roles
      • 12 Principles of Agile
      • Zettel
      • Cognitive Bias
        • Present Bias
        • Sunk cost fallac
        • Ikea Effect
    • Architecture Development
      • Architectural-"ilities"
      • Architectual Considerations
    • Devops
      • Check The Status of All Services
      • Running Out Of inode Space
      • SSL Certificates Can Cover Multiple Domains
    • Documentation
      • 🧜Mermaid
        • 🧜Mermaid-Flowchart
        • 🧜‍♀️Mermaid-Sequence
        • 🧜‍♂️Mermaid-Gnatt
      • ⬇️Markdown
      • MediaWiki
    • Networking
      • Applications
        • NMAP
        • Scappy
        • TCP Dump
        • Wireshark
      • Common Ports
      • Cabling
      • Protocols
        • BGP
        • EIGRP
        • First Hop Redundancy
        • IEEE 802.1X
        • IEEE 802.11 WLAN
        • IP Security
        • IPv4 Multi-cast
        • IPv4 Subnetting
        • IPv6
        • IS-IS
        • OSPF
        • Point to Point
        • RIP
        • Spanning Tree
      • Technologies
        • Frame Mode MPLS
        • IOS (Cisco)
        • Network Address Translation
        • Quality of Service
        • VLANs
        • VOIP Basics
      • Resolve The Public IP Of A URL
      • Path Of The Packets
      • Determine The IP Address Of A Domain
      • Allow HTTPS Through Your UFW Firewall
      • Allow Cross-Origin Requests To Include Cookies
    • Virtualization
      • Ubuntu
        • Ubuntu Quick Install
        • Hyper-V - Setup an Ubuntu 20.04 vm
        • Virtual Box - Setup an Ubuntu 20.04 vm
        • Virtual Box - Setup an Ubuntu 22.04 vm
      • RedHat
        • Setup RHEL 9.2 Linux vm
      • Fedora
        • Setup Fedora 38 Linux vm
      • Transfer files from Windows to Linux VM
    • Security/Hacking
      • Reference
        • Big Data Security
        • Cryptography
        • Code Reviews
        • Forensic Challenges
        • PenTesting Challenges
        • PKI
        • VOIP
        • Virus Classification
        • VMs and Live CDs
        • Worm Classification
      • Forensics
      • Tests
        • Browser Plugins
        • Infrastructure tests
        • Security Tests
        • Securing Home Computers
        • Web Application Security Test
        • VPN
        • Wireless Network Review
      • Tools
        • Metasploit - 4.5
  • 💻os
    • 🐧linux
      • Reference
      • ubuntu-specific
        • Upgrading Ubuntu
        • Check Ubuntu Version
        • Config ubuntu 20.04 vm for rdp
      • alias
        • Ignore The Alias When Running A Command
      • crypto
        • Generate A SAML Key And Certificate Pair
      • datetime
        • Figure Out The Week Of The Year From The Terminal
        • Show Current System Time And Settings
        • Configure Your Server Timezone
        • Get The Unix Timestamp
        • Touch Access And Modify Times Individually
        • Format And Print The Current Date And Time
      • disk
        • Display Free Disk Space
        • Show Disk Usage For The Current Directory
      • directory
        • Change To That New Directory
        • Check The Current Working Directory
        • Configure cd To Behave Like pushd In Zsh
        • Display The Contents Of A Directory As A Tree
        • Copying Nested Directories With Ditto
        • Globbing For Filenames In Zsh
        • Globbing For All Directories In Zsh
        • Use fzf To Change Directories
        • Show The Size Of Everything In A Directory
        • List The Stack Of Remembered Directories
      • file
        • Copying File Contents To System Paste Buffer
        • Do Not Overwrite Existing Files
        • File Type Info With File
        • Find Files With fd
        • Find Newer Files
        • Get Matching Filenames As Output From Grep
        • Hexdump A Compiled File
        • List Files Ordered By Modification Date
        • List Names Of Files With Matches
        • List Stats For A File
        • Create A File Descriptor with Process Substitution
        • Print Out Files In Reverse
        • Securely Remove Files
        • Print A Range Of Lines For A File With Bat
      • http
        • Curl With Cookies
        • Curling For Headers
        • Curling With Basic Auth Credentials
      • history
        • Jump To The Ends Of Your Shell History
        • Last Argument Of The Last Command
        • Global Substitution On The Previous Command
        • Search History
      • java
        • List The Available JDKs
      • networking
        • Check If A Port Is In Use
        • Kill Everything Running On A Certain Port
        • Map A Domain To localhost
        • List Of Sessions To A Machine
      • package management
        • Get Repo's
        • Hold package version - do not upgrade
        • Install a Specific Version of Package
        • Switch Versions of a Brew Formula
        • Switch between Local & remote packages
      • process
        • PID Of The Current Shell
        • Open The Current Command In An Editor
        • List Parent pid With ps
        • Check If Command Is Executable Before Using
        • Exclude Certain Files From An rsync Run
        • List The Statuses Of All Upstart Jobs
        • Do A Dry Run Of An rsync
        • Where Are The Binaries?
        • Watch This Run Repeatedly
      • shells
        • Change Default Shell For A User
      • terminal
        • Clear The Screen
        • Cat Files With Color Using Bat
        • Display All The Terminal Colors
        • Cat A File With Line Numbers
        • Less With Style
        • View A Web Page In The Terminal
        • Undo Some Command Line Editing
        • Command Line Length Limitations
        • Saying Yes
        • Watch The Difference
      • string
        • Repeat Yourself
      • ssh
        • Killing A Frozen SSH Session
        • Forward Multiple Ports Over SSH
        • SSH Escape Sequences
        • Specify The Language For A File With Bat
        • SSH With Port Forwarding
      • search/query
        • Count The Number Of Matches In A Grep
        • Enable Multi-Select Of Results With fzf
        • Exclude A Directory With Find
        • Find A File Installed By Brew
        • Grep For Files With Multiple Matches
        • Grep For Multiple Patterns
        • Grep For Files Without A Match
        • Partial String Matching In Bash Scripts
        • Only Show The Matches
        • Search Files Specific To A Language
        • Search Man Page Descriptions
        • Show A File Preview When Searching With FZF
        • Use Regex Pattern Matching With Grep
        • Skip Paging If Output Fits On Screen With Less
        • Sort In Numerical Order
      • user
        • List All Users
      • variables
        • All The Environment Variables
        • Compare Two Variables In A Bash Script
        • Provide A Fallback Value For Unset Parameter
        • Check If The First Argument Is Given
    • 🍎mac
      • Access All Screen And Video Capture Options
      • Access System Information On OS X
      • Access Unsupported Screen Resolutions With RDM
      • Clean Up Old Homebrew Files
      • Convert An HEIC Image File To JPG
      • Default Screenshot Location
      • Disable Swipe Navigation For A Specific App
      • Display A Message With Alfred
      • Find The Process Using A Specific Port
      • Gesture For Viewing All Windows Of Current App
      • Insert A Non-Breaking Space Character
      • List All The Say Voices
      • Quickly Type En Dashes And Em Dashes
      • Require Additional JS Libraries In Postman
      • Resize App Windows With AppleScript
      • Resizing Both Corners Of A Window
      • Run A Hardware Check
      • Run AppleScript Commands Inline In The Terminal
      • Set A Window To Its Default Zoom Level
      • Specify App When Opening From Command Line
      • Use Default Screenshot Shortcuts With CleanShot X
      • View All Windows Of The Current App
    • 🪟win
      • Windows Reference
      • powershell
        • Formatting
        • Base64
        • Environment Variables
        • Modules
          • Pwsh Profile
          • Logging.psm1
        • Setup console with posh-git
    • 🚇wsl
      • Install Jupyter in WSL
  • 👩‍💻programmy
    • azure
      • Setup Azure VM Ubuntu Server to be Desktop
      • Azure Cli
        • Azure Repos Export
        • Azure Keyvault
        • Azure Functions
        • Azure Networking
          • Setup VPN Certificates
        • Azure Subscriptions
        • Azure Roles
          • Azure Storage Ac
    • aad
      • AzureAD.Get-Devices
      • Desktop Joining/Trust
    • databases
      • mysql
        • Display Output In A Vertical Format
        • Doing Date Math
        • Dump A Database To A File
        • List Databases And Tables
        • Show Create Statement For A Table
        • Show Tables That Match A Pattern
        • Show Indexes For A Table
      • mongodb
        • Determine The Database Version
        • Dump A Remote Database
        • Get Size Stats For A Collection
        • List Size Stats For All Collections
      • mssql
      • postgres
        • commands
          • Triggers
          • Use A psqlrc File For Common Settings
          • Switch The Running Postgres Server Version
          • Track psql History Separately Per Database
          • Toggling The Pager In PSQL
          • Temporarily Disable Triggers
          • Sets With The Values Command
          • Set A Statement Timeout Threshold For A Session
          • Send A Command To psql
          • Sleeping
          • Set Inclusion With hstore
          • Prepare, Execute, And Deallocate Statements
    • linux
      • Limit Execution Time Of Statements
      • Install Postgres With uuid-ossp Using asdf
      • Find The Location Of Postgres Config Files
      • Find The Data Directory
      • Create hstore From Two Arrays
      • Insert Just The Defaults
      • Stop a Service
      • Is App Installed?
        • Change The Current Directory For psql
        • Check If The Local Server Is Running
        • connections
          • Connect To An RDS PostgreSQL Database
          • Terminating A Connection
          • List Connections To A Database
          • Force SSL When Making A psql Connection
        • Crypto
          • Salt And Hash A Password With pgcrypto
          • Set A Seed For The Random Number Generator
          • Generating UUIDs With pgcrypto
          • Compute The md5 Hash Of A String
          • Compute Hashes With pgcrypto
        • Database Operations
          • List Database Objects With Disk Usage
          • List All The Databases
          • Get The Size Of A Database
          • Dump All Databases To A SQL File
          • Duplicate A Local Database
          • Dump And Restore A Database
          • Create Database Uses Template1
        • DateTime Operations
          • Timestamp Functions
          • Using Intervals To Offset Time
          • Turning Timing On
          • Intervals Of Time By Week
          • Convert A String To A Timestamp
          • Day Of Week For A Date
          • Determining The Age Of Things
          • Day Of Week By Name For A Date
          • Constructing A Range Of Dates
          • Configure The Timezone
        • Functions
          • List All Versions Of A Function
          • Group By The Result Of A Function Call
          • Edit Existing Functions
        • File Operations
          • Extracting Nested JSON Data
          • Export Query Results To A CSV
        • IDE/Display
          • Auto Expanded Display
          • Clear The Screen In psql
          • Clear The Screen In psql (2)
        • Indexing
          • Use Argument Indexes
          • Using Expressions In Indexes
          • Adding Composite Uniqueness Constraints
          • Add Foreign Key Constraint Without A Full Lock
          • Create A Composite Primary Key
          • Create An Index Without Locking The Table
          • Add ON DELETE CASCADE To Foreign Key Constraint
        • Math Operations
          • Two Ways To Compute Factorial
          • Integers In Postgres
          • Generate Series Of Numbers
          • Count The Number Of Trues In An Aggregate Query
          • Count Records By Type
          • Count How Many Records There Are Of Each Type
          • Assumed Radius Of The Earth
          • Compute The Levenshtein Distance Of Two Strings
        • Queries
          • Write A Query Result To File
          • Union All Rows Including Duplicates
          • Truncate All Rows
          • Use Not Valid To Immediately Enforce A Constraint
          • Storing Emails With citext
          • Print The Query Buffer In psql
          • Prevent A Query From Running Too Long
          • Insert A Bunch Of Records With Generate Series
          • Find Records That Have Multiple Associated Records
          • Find Records That Contain Duplicate Values
          • Between Symmetric
          • Difference Between Explain And Explain Analyze
          • Creating Conditional Constraints
          • Aggregate A Column Into An Array
        • Schema
          • pg Prefix Is Reserved For System Schemas
          • List All Columns Of A Specific Type
          • Default Schema
        • Sequence
          • Restart A Sequence
          • Renaming A Sequence
          • List Available Schemas
        • String Operations
          • Two Ways To Escape A Quote In A String
          • Word Count for a Column
          • String Contains Another String
          • Pretty Printing JSONB Rows
          • Pretty Print Data Sizes
          • Escaping String Literals With Dollar Quoting
          • Escaping A Quote In A String
          • Capitalize All The Words
          • A Better Null Display Character
        • Table Operations
          • Restarting Sequences When Truncating Tables
          • Temporary Tables
          • Renaming A Table
          • Truncate Tables With Dependents
          • List All Rows In A Table
          • Get The Size Of A Table
          • Get A Quick Approximate Count Of A Table
          • Fizzbuzz With Common Table Expressions
          • Find Duplicate Records In Table Without Unique Id
          • Create Table Adds A Data Type
          • Check Table For Any Oprhaned Records
        • Types & Operators
          • Special Math Operators
          • The nullif Function
          • Types By Category
          • Shorthand Absolute Value Operator
          • Show All Versions Of An Operator
          • Switch Non-Castable Column Type With Using Clause
          • Remove Not Null Constraint From A Column
          • List Various Kinds Of Objects
          • Max Identifier Length Is 63 Bytes
          • Lower Is Faster Than ilike
          • Is It Null Or Not Null?
          • Getting A Slice Of An Array
          • Get The Size Of An Index
          • Generate A UUID
          • Generate Random UUIDs Without An Extension
          • Determine Types Of JSONB Records
          • Defining Arrays
          • Creating Custom Types
          • Checking The Type Of A Value
          • Checking Inequality
        • User Operations
          • Who Is The Current User
          • List Database Users
      • pgbouncer
        • Backup Databse
        • pgbouncer
    • c#
    • chrome
      • Access A Value Logged To The Console
      • Chrome Supports Many Unix Keyboard Shortcuts
      • Copy Some Data From The Console
      • Duplicate The Current Tab
      • Easier Access To Network Throttling Controls
      • Pretty Print Tabular Data
      • Reference The Selected Node
      • Selecting DOM Elements Faster Than Ever
      • Simulating Various Connection Speeds
      • Toggle Device Mode
      • Toggle Open The Console Drawer
      • View Network Traffic For New Tabs
    • clojure
      • Aggregation Using merge-with
      • Argument Requirements For A Function
      • Combinations Of Items From A Sequence
      • Define Something Only Once
      • Evaluate One Liners With lein-exec
      • Expanding Macros
      • Get The Value Of An Environment Variable
      • List Functions For A Namespace
      • Load A File Into The REPL
      • Mapping With An Index
      • Open JavaDocs
      • Pretty Print The Last Thing
      • Quick Clojure Docs
      • Reductions
      • Set Max Heap Size
      • Specify the Directory of a Shell Command
      • Splitting On Whitespace
      • Swap Two Items in a Vector
      • Try A Clojure Project In The REPL
      • Type of Anything
      • When Overflow Is Desired
    • css
      • Add Fab Icons To Your Site With FontAwesome 5
      • Animate Smoothly Between Two Background Colors
      • Apply Multiple Box Shadows To Single Element
      • Apply Styles Based On Dark-Mode Preferences
      • Apply Styles To The Last Child Of A Specific Type
      • Change The Orientation Of An Image
      • Circular Icons With A Massive Border Radius
      • Clean Up Repetition With :is() Pseudo-Class
      • Conditional Styling For Unsupported CSS Features
      • Create A Pulsing Background With CSS Animation
      • Define CSS Custom Properties With CSS Variables
      • Define HSL Colors With Alpha Values
      • Display Responsive iframe Maintaining Aspect Ratio
      • Dry Up SCSS With Mixins
      • Give Elements The Same Width With Flexbox
      • Let Pointer Events Pass Through An Element
      • Lighten And Darken With CSS Brightness Filter
      • Lighten And Darken With SCSS
      • Make A Block Of Text Respect New Lines
      • Parameterized SCSS Mixins
      • :root Has Higher Specificity Than html
      • Style A Background With A Linear Gradient
      • Using Maps In SCSS
    • elixir
      • All Values For A Key In A Keyword List
      • Append To A Keyword List
      • Assert An Exception Is Raised
      • Binary Representation Of A String
      • Check For A Substring Match
      • Check List Membership
      • Comparing DateTime Structs
      • Compute Intermediate Values In A With Construct
      • Compute md5 Digest Of A String
      • Counting Records With Ecto
      • Create A Date With The Date Sigil
      • Create A List Of Atoms
      • Creating A PID
      • Creating Indexes With Ecto
      • Defining Multiple Clauses In An Anonymous Function
      • Determine The Latest Release Of A Hex Package
      • Do You Have The Time?
      • Do You Have The Time? - Part 2
      • Documentation Lookup With Vim And Alchemist
      • Dynamically Generating Atoms
      • Execute Raw SQL In An Ecto Migration
      • Expose Internal Representation
      • Include Captures With String.split
      • Inspecting The Process Message Queue
      • List Functions For A Module
      • Listing Files In IEx
      • Match On A Map In A With Construct
      • Passing Around And Using Modules
      • Pattern Matching In Anonymous Functions
      • Pipe Into A Case Statement
      • Quitting IEx
      • Range Into List Using Comprehensions
      • Refer To A Module Within Itself
      • Referencing Values In IEx's History
      • Remove One List From Another
      • Replace Duplicates In A Keyword List
      • Requiring Keys For Structs
      • Reversing A List
      • Reversing A List - Part 2
      • Root Directory Of A Project
      • Round Floats To Integers
      • Run ExUnit Tests In A Deterministic Order
      • Run The Test At A Specific Line Number
      • Same Functions Should Be Grouped Together
      • Skip A Specific Test
      • String Interpolation With Just About Anything
      • Unique Indexes With Ecto
      • Updating Values In A Map
      • Using When Clauses In A With Construct
      • Virtual Fields With Ecto Schemas
      • When Things Don't Match The With Statements
      • Word Lists For Atoms
    • go
      • Access Go Docs Offline
      • Build For A Specific OS And Architecture
      • Not So Random
      • Replace The Current Process With An External Command
      • Sleep For A Duration
      • Upgrading From An Older Version On Mac
    • heroku
      • Wipe A Heroku Postgres Database
      • Push Non-master Branch To Heroku
    • html
      • Adding Alt Text To An Image
      • Disable Auto-Completion For A Form Input
      • Prevent Search Engines From Indexing A Page
      • Render Text As Superscript
      • Submit A Form With A Button Outside The Form
    • javascript
      • Accessing Arguments To A Function
      • Basic Date Formatting Without A Library
      • Character Codes from Keyboard Listeners
      • Check Classes On A DOM Element
      • Check If Something Is An Array
      • Check The Password Confirmation With Yup
      • Compare The Equality Of Two Date Objects
      • Computed Property Names In ES6
      • Conditionally Include Pairs In An Object
      • Configure Jest To Run A Test Setup File
      • Create A Cancelable Promise With PCancelable
      • Create An Array Containing 1 To N
      • Create An Object With No Properties
      • Create Bootstrapped Apps With Yarn
      • Create Future And Past Dates From Today
      • Custom Type Checking Error Messages With Yup
      • Default And Named Exports From The Same Module
      • Define A Custom Jest Matcher
      • Destructure With Access To Nested Value And Parent Value
      • Destructuring The Rest Of An Array
      • Enable ES7 Transforms With react-rails
      • Ensure Shell Can Find Global npm Binaries
      • Easy Date Comparison With DayJS
      • Expand Emojis With The Spread Operator
      • Fill An Input With A Ton Of Text
      • Find Where Yarn Is Installing Binaries
      • for...in Iterates Over Object Properties
      • Formatting Values With Units For Display
      • Freeze An Object, Sorta
      • Generate Random Integers
      • Get The Location And Size Of An Element
      • Get The Response Status From An Axios Error
      • Get The Time Zone Of The Client Computer
      • Globally Install A Package With Yarn
      • Immutable Remove With The Spread Operator
      • Initialize A New JavaScript Project With Yarn
      • Install The Latest Version Of Node With Nvm
      • Interpolate A String Into A Regex
      • ISO-8601 Formatted Dates Are Interpreted As UTC
      • Link A JavaScript Package Locally
      • List Top-Level NPM Dependencies
      • Make The Browser Editable With Design Mode
      • Matching A Computed Property In Function Args
      • Matching Multiple Values In A Switch Statement
      • Mock A Function With Return Values Using Jest
      • New Dates Can Take Out Of Bounds Values
      • Numbers Are Empty
      • Object Initialization With Shorthand Property Names
      • Obtain Undefined Value With The Void Operator
      • Parse A Date From A Timestamp
      • Random Cannot Be Seeded
      • Reach Into An Object For Nested Data With Get
      • Render An Array Of Elements With React 16
      • Resolve And Pass Multiple Values From A Then
      • Running ES6 Specs With Mocha
      • Scoping Variables With A Block Statement
      • Sleep For A Bit In Async Code
      • Sorting Arrays Of Objects With Lodash
      • Splat Arguments To A Function
      • Spread The Rest With ES6
      • Start Node Process In Specific Timezone
      • String Interpolation With Template Literals
      • Support Nested Matching In Custom Jest Matchers
      • Tell Prettier To Not Format A Statement
      • Test Coverage Stats With Jest
      • Test Timing-Based Code With Jest Fake Timers
      • The Comma Operator
      • Throttling A Function Call
      • Timing Processes
      • Transforming ES6 and JSX With Babel 6
      • Truthiness of Integer Arrays
      • Turn An HTMLCollection Into An Array
      • Turn Off Console Error Messages In A Test
      • Waiting On Multiple Promises
      • Who Am I: NPM Edition
      • Yarn Commands Without The Emojis
      • Yup Schemas Are Validated Asynchronously
    • ml
      • reasonML
        • Break Out Of A While Loop
        • Compile Reason To Native With Dune
        • Compile Reason With An OCaml Package Using Dune
        • Create A Map Of Strings
        • Create A Stream From An Array
        • Creating A 2D Array
        • Data Structures With Self-Referential Types
        • Defining Variants With Constructor Arguments
        • Dynamically Create A Printf String Format
        • Exhaustive Pattern Matching Of List Variants
        • Format The Current File Within Vim
        • Generate A Native ReasonML Project With Pesy
        • Generate Starter Reason Projects
        • Helping The Compiler Help Us With Variants
        • Inline Component Styles With Reason React
        • Is This A Directory Or A File?
        • Making Things Mutable
        • Modifying A String With blit_string
        • Multi-Argument Functions As Syntactic Sugar
        • Pattern Match On Exceptions
        • Quickly Bootstrap A React App Using Reason
        • Seeding And Generating Random Integers
        • Stream A File Line By Line
        • String Interpolation With Integers And Sprintf
        • String Interpolation With Quoted Strings
        • Trying Out ReasonML In CodeSandbox
        • Two Ways To Find An Item In A List
        • Using Optional Labeled Function Arguments
        • Wrapping A Component For Use In JavaScript
    • node
      • asdf
        • Fix Unlinked Node Binaries With asdf
        • Interactively Browse Available Node Versions
        • Set The asdf Package Version For A Single Shell
        • Update Package Versions Known By asdf Plugin
    • php
    • python
      • Access Instance Variables
      • Create A Dummy DataFrame In Pandas
      • Test A Function With Pytest
    • rails
      • Add A Check Constraint To A Table
      • Add A Foreign Key Reference To A Table
      • Add A Reference Column With An Index
      • Add ActiveRecord Error Not Tied To Any Attribute
      • Add React With Webpacker To A New Rails App
      • Add timestamptz Columns With The Migration DSL
      • Access Secrets In A Rails 5.2 App
      • ActiveRecord Query For This Or That
      • Advance The Date
      • Allow List Params Anywhere With Strong Params
      • All or Nothing Database Transactions
      • Assert Two Arrays Have The Same Items With RSpec
      • Attach A File With Capybara
      • Attribute Getter without the Recursion
      • Attribute Was
      • Autosave False On ActiveRecord Associations
      • Bind Parameters To ActiveRecord SQL Query
      • Build A Hash Of Model Attributes
      • Capture Development Emails With Mailhog
      • Capybara Page Status Code
      • Cast Common Boolean-Like Values To Booleans
      • Change The Nullability Of A Column
      • Change The Time Zone Offset Of A DateTime Object
      • Check If ActiveRecord Update Fails
      • Check If Any Records Have A Null Value
      • Check Specific Attributes On ActiveRecord Array
      • Code Statistics For An Application
      • Columns With Default Values Are Nil On Create
      • Comparing DateTimes Down To Second Precision
      • Conditional Class Selectors in Haml
      • Convert A Symbol To A Constant
      • Count The Number Of Records By Attribute
      • Create A Custom Named References Column
      • Create A Join Table With The Migration DSL
      • Creating Records of Has_One Associations
      • Custom Validation Message
      • Customize Paths And Helpers For Devise Routes
      • Customize The Path Of A Resource Route
      • Delete Paranoid Records
      • Demodulize A Class Name
      • Different Ways To Add A Foreign Key Reference
      • Disambiguate Where In A Joined Relation
      • Ensure Migrations Use The Latest Schema
      • Find Or Create A Record With FactoryBot
      • Force All Users To Sign Out
      • Generating And Executing SQL
      • Get An Array Of Values From The Database
      • Get An Empty ActiveRecord Relation
      • Get The Column Names For A Model
      • Get The Current Time
      • Grab A Random Record From The Database
      • Handle Named Arguments In A Rake Task
      • Hash Slicing
      • Ignore Poltergeist JavaScript Errors
      • Include Devise Helpers In Your Controller Tests
      • Inspect Previous Changes To ActiveRecord Object
      • Link To The Current Page With Query Params
      • List All Installable Rails Versions
      • List The Enqueued Jobs
      • Load Records In Batches With find_each
      • Log SQL Queries Executed By ActiveRecord
      • Mark A Migration As Irreversible
      • Make ActionMailer Synchronous In Test
      • Manually Run A Migration From Rails Console
      • Mark For Destruction
      • Mask An ActiveRecord Attribute
      • Merge A Scope Into An ActiveRecord Query
      • Migrating Up Down Up
      • Order Matters For rescue_from Blocks
      • Params Includes Submission Button Info
      • Parse Query Params From A URL
      • Perform SQL Explain With ActiveRecord
      • Polymorphic Path Helpers
      • Pretend Generations
      • Prevent Writes With A Sandboxed Rails Console
      • Query A Single Value From The Database
      • Read In Environment-Specific Config Values
      • Read-Only Models
      • Remove The Default Value On A Column
      • Render An Alternative ActionMailer Template
      • Render The Response Body In Controller Specs
      • Replace An Index With A Unique Index
      • Rescue From
      • Rescue From With A Separate Method
      • Retrieve An Object If It Exists
      • Rollback A Specific Migration Out Of Order
      • Rounding Numbers With Precision
      • Schedule Sidekiq Jobs Out Into The Future
      • Secure Passwords With Rails And Bcrypt
      • Select A Select By Selector
      • Select Value For SQL Counts
      • Serialize With fast_jsonapi In A Rails App
      • Set A Timestamp Field To The Current Time
      • Set default_url_options For Entire Application
      • Set Schema Search Path
      • Set Statement Timeout For All Postgres Connections
      • Set The Default Development Port
      • Show Pending Migrations
      • Show Rails Models With Pry
      • Show Rails Routes With Pry
      • Skip Validations When Creating A Record
      • Specify New Attributes For #find_or_create_by
      • Temporarily Disable strong_params
      • Test If An Instance Variable Was Assigned
      • Test If deliver_later Is Called For A Mailer
      • Truncate Almost All Tables
      • Update Column Versus Update Attribute
      • Upgrading Your Manifest For Sprocket's 4
      • Verify And Read A Signed Cookie Value
      • Where Am I In The Partial Iteration?
      • Wipe Out All Precompiled Assets
      • Write Reversible Migration To Set Default
      • Write Safer Where Clauses With Placeholders
    • react
      • A Component Is Just A Bag Of Data
      • Access The Latest Lifecycle Methods In An Old App
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      • Accessing Location Within @reach/router
      • Allow md As An Extension With gatsby-mdx
      • Alter The Display Name Of A Component
      • Building A React App In The Browser
      • Check The Type Of A Child Component
      • Conditionally Including Event Handler Functions
      • Create A Snowpack-Bundled React App
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      • create-react-app Comes With Lodash
      • create-react-app Has A Default Test Setup File
      • CSS !important Is Not Supported By Inline Styles
      • Debug Jest Tests In create-react-app
      • Defining State In A Simple Class Component
      • Destructure Variables As Props To A Component
      • Details Tags Are A Controllable Component
      • Dispatch Anywhere With Redux
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      • Enforce Specific Values With PropTypes
      • Focus An Input With useRef Hook
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      • Inline Style Attributes Should Be Camel Cased
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      • Mapping Over One Or Many Children
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      • Navigate With State Via @reach/router
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      • Passing Props Down To React-Router Route
      • Prevent reach/router Redirect Error Screen In Dev
      • Proxy To An API Server In Development With CRA
      • Quickly Search For A Component With React DevTools
      • @reach/router Renders To A Div
      • Read Only Input Elements
      • Rendering Multiple Nodes With Fragments
      • Set The Type For A useState Hook
      • Specifying Dependencies Of A useEffect Hook
      • Spelunking Through Components With Enzyme's Dive
      • Sync Your react-router State With Redux
      • Test Files In create-react-app
      • Test That Element Does Not Render In The Component
      • Trigger Effect Only When The Component Mounts
      • Update Formik Initial Values When Props Change
      • Upgrading To The Latest React In CodeSandbox
      • Use A Ref To Autofocus An Input
      • Use React 16 With Gatsby
      • Use withRouter To Pass Down React-Router History
      • Visually Select A React Element For Inspection
      • Who Is Your Favorite Child?
      • Wrap The Root Of A Gatsby App In A Component
    • react native
      • Avoid The Notch With SafeAreaView
    • react testing library
      • Check That A Component Renders As Null
      • findBy* Queries Have Async Built In
      • Pretty Print Some DOM To Debug A Test
      • Test A Component That Uses React Portals
    • regEx
    • ruby
      • A Basic Case Statement
      • A Shorthand For Rerunning Failed Tests With RSpec
      • Add Comments To Regex With Free-Spacing
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  1. programmy
  2. ruby

Construct A Constant From A String

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Last updated 3 years ago

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Ruby's can be used to look for and retrieve the constant for a given name.

This can be used to construct a class name

> Object.const_get("Math")
#=> Math
> Object.const_get("Math")::PI
#=> 3.141592653589793

It can also be used to reference a constant

> Object.const_get("Math::PI")
#=> 3.141592653589793

You can even be more specific if you'd like

> Math.const_get("PI")
#=> 3.141592653589793

Symbols are valid as well

> Math.const_get(:PI)
#=> 3.141592653589793
👩‍💻
Module.const_get