joeyharbert/TIL.md

## TIL.md

      
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    2/17:

I learned that SQL is a relational database (much like a spreadsheet). I also learned that documents llike this are useful to prove knowledge, as well as helping concretize knowledge and have a place of reference for things in case I forget something. I also learned that "```" (three backticks) will start and end a block of code format in this file. If you put the programming language after the opening backticks in lowercase (on it's own line) it will give you syntax highlighting for that language.
ls -l = -l is a list flag for terminal
ls -a: -a flag that shows files starting with '.'
clear terminal command
ls -GF gives syntax highlighting
cd ..  goes up a level of file (I keep forgetting that)
pwd = print working directory
mkdir = make directory (make a new folder)
touch = make file
cat = to show file contents
rm = remove file
rmdir = remove directory (only works if the folder is empty)
rm -rf = remove directory and contents (adult delete)
history # = where # is the number of commands, shows the command history (you can use the command number with !#)
!! = runs the previous line of code
sudo stands for super user do (run as admin)
tab for autocomplete in terminal
git init = start git track
Commit version
git add --all
git commit -m "message"


git status = checks if last save == current file
git diff = tells what's changed since last commit
git log = tells who did what when
commit messages are always in present tense

2/18

HOD (hotkey of the day): cmd + tab (same as alt+tab on windows) cycle through programs
"cmd + /" to comment out a block of text
"cmd + d" highlights next instance of a word and allows you to edit both
when creating repository the name has to exactly match the file name in your computer
in ruby, single and double quotes operate the same until you try interpolation (concat is fine)
this is because single quotes are faster than double quotes, so the ruby community prefers double quotes unless you need interpolation.
cmd + shift + d = copies current line
you can write a hash with key: value instead of key => value
cmd + shift + enter = creates a new line above the line you're on
shift + option = selects word

2/19

HOD: cmd + space: spotlight search (We been knew sis)
'git checkout .' returns to last commit
in sublime press k then b to show file system you're in
within a class, if you're calling a method inside another method, ruby checks first to see if there is a local variable of that name.     Second it will check for local methods.
#/ to end a "block" of comments eg: # getter methods ......code..... #/getter methods
cmd + down = gets you to end of file
attr_reader :variable1, :variable2, etc  is equivalent of getter method
attr_writer :var1, :var2, var3  is same for setter method
^^^ always at beginning of class before init
you can use a hash to allow more flexible initialization of a class
when you're passing a hash into an instance of a new class, you don't need to use the curly braces inside the parentheses
'<' for inherit classes
you can only inherit from one class, but you can chain inherits
'super' checks what we're inheriting from and brings all that code down (so we are able to add to a method without overriding it)

2/20

HOD: cmd + shift + tab = backwards cmd + tab
cntrl+shift+right  highlights word
module naming usually ends in -able
looks like class, holds methods for multiple classes to access (wrapper for a bunch of methods)
to use a module use the keyword 'include {modulename}' in the class
classes Capitalized, singular, camelcase
require is normally used for gem, but you can use it for files you just need to use './' to have require look
in the folder you're in. require './filename.rb' to use other files (for classes and such)
require_relative does same thing as require you just don't have to use './' (it means start looking in this directory not in the gem directory)
cmd + ] is tab for highlighted text
you can use a module to wrap a class so that your class doesn't override classes with the same name
you call it by using Module::Class

2/21

cmd + option + 2 for split screen in sublime
Web verbs: - GET is for reading
- POST is for changing
- PATCH is for updating
- DELETE is for removing (duh)
Technically, patch and delete are sub-commands of post
API generally refers to making web requests and getting back JSON data (instead of HTML), though API is a much, much broader term.
Status code:  -100 = info
-200 = Success
-300 = Redirect
-400 = Client Error (your fault)
-500 = Server Error (developer fault/my fault)
ALWAYS DELETE API KEY BEFORE PUSHING CODE

2/24 RAILS DAY

HOD: cmd + enter = move from middle of line to next line
cmd + shift + enter = move up a line
opt + right arrow move my word instead of character
rails won't work until you have a database (you'll get an error)
"rails server" makes a testing server on your computer
Beginning commads for creating a rails app (for now)

    rails new sample_app
    cd sample_app
    rails generate controller api/example_pages
    rails db:create
    rails server


Steps once you hit enter to get a website:

▼ ▼ ▼ ▼ STEPS ▼ ▼ ▼ ▼
---------------------
1. WEB REQUEST
2. API ROUTE
3. API CONTROLLER (gets data from MODEL)
4. API VIEW
5. WEB RESPONSE 


cmd + shift + d = copies a line
If the error doesn't pop up on the screen, you can check your server messages for the error

2/25

HOD: cmd + down/up brings you to bottom/top of file
.sample picks raandom element out of an array
.shuffle randomly shuffles an array
cmd + cntrl + up/down to move lines
MODEL is ruby class that takes data from database, packages it into a ruby class that we can access
controller name is plural of model

    rails db: migrate


CRUD = Create Read Update Delete (or Destroy)
Model automatically has initialize function (even though it's not in the file) that takes in an options hash that has the keys and values of our generate model command
if an instance of a model has an id it is in the database, if the id is nil, then it is not in the database
any time you modify an instance of a model, you have to save it to the database again

2/26
json.array! @array_name.each do |item|
  #normal json assignment code 
end 


to add gem to web app, add to Gemfile, stop server, use 'bundle install'
sql vs no-sql databases
sql more popular and older, no-sql is up and coming
sql operates as spreadsheet, but no-sql can operate in other was (such as key value pairs)
MVC = Model View Controller
Model defines how we interact with stored information
Model = stored data
View = Interface
-JSON or HTML, forms, UI
Controller = Logic Flow
-usually involves if statements filters or CRUD operations.
-combines all these pieces together
Ideally, want to do calculations in the Model, not Controller
cmd + cntrl + up/down = moves a line up or down
if a method only returns boolean the name should end with a question mark

2/27

query string, url, body parameters to get dynamic info from user
rails knows that once it sees a question mark in a route that everything after is a query
rails will then create a hash of key value pairs (called params) based on the queries
in params you can call strings and symnbols both for they key (they are strings, but traditionally people use symbols)

2/28

HOD: can cmd + c without higlighting on a line in sublime
by default, rails won't accept anything that's not a get request that's not from within rails
To get around this:
protext_from_forgery with: :null_session  in application_controller.rb

3/3

HOD: cmd + ~ switch between windows of an application
cmd + opt + [a number] = split screen in sublime

3/5

if you're in the views folder and the file begins with an underscore, then it's a partial
json.partial! "blah.json.jbuilder", noun: @noun  notice that there is no underscore before the filename

3/6

Upper camel case for migration file
rails generate migration NameOfFile 
migrations can act as version control for your database
use _ for previous command (so x = _)
learned about validations see documentation
.save fails quietly, returns false
use .errors.full_messages to return an array of all the error messages

3/7

SQL SELECT column1, column2 FROM table;
SELECT * FROM table; Select all

    WHERE column = 'something' ```


Only use single equal in SQL
Only single quote in Postico
chain WHERE's together with AND
    WHERE blah
    AND   blah; ```


    WHERE blah
    OR blah;   ```


LIMIT number;
ORDER BY column; 
WHERE ingredients LIKE '%blah%';  search for string within a string
SELECT COUNT(*) FROM table
SUM, COUNT, AVG (Average)

3/10

can use .where(key: "value") in ruby like WHERE in SQL
one to many relationship: one object owns/or is attached to many objects

3/11

Normalizing = DRYing up talbles by splitting them up
primary key - key on current table
foreign key - key pointing to a different table
'g' is shortcut for generate in console e.g. 'rails g migration'
likewise 's' works for server
reload! does the same thing as exiting out and reloading rails console
use 'belongs_to :parent' in place of connecting parent to child

in order for this to work, the table has to be named correctly, there has to be a parent_id column


conversely has_many works to connect child to parent

3/12

if you have a belongs_to, it automatically creates a validation so that the child has to reference an instance of the parent when being created
ls -ltr lists files by most recently added
cmd + shift + d duplicates line

3/13

HOD: shift + cntrl + left/right : highlight until capital letter or _

3/14

CHECK YOUR SERVER FOR ERRORS (when working with front end)

3/17

For many to many, create "join table" that houses id's
name the joiner by smashing the two names together e.g. for products and categories tables, the join name would be category_products
name should be in alphabetical order (categoryproducts not productcategories)

3/18

HOD: fn + del: is backwards delete

3/19

cntrl + tab cycles through tabs (based on most recent in sublime)

3/20

rails s -p 3001 = runs rails server on localhost:3001
with figaro, you have to restart your server anytime you edit the application.yml file

3/21

HOD: cmd + option + left bracket : collapses HTML tags

 forms can be used to make a request!

<% %> to run ruby code <%= %> to render in HTML in erb
redirect_to works like a link in ruby
For constant header and footer use application.html.erb in layouts (in views)

3/23


cmd + opt + j = view source


chrome only understands get and post requests by default


 <- patch workaround


rel="nofollow" tells the bots to not click this link


Capstone:

Idea
User stories
-Trello
-See Brian
Does the data I need exist? (N/A for me)
Schema
What happens in db for each user story
rails new ... API
test associations in rails console (see if everything is wired up correctly)
make rest of app...


MVP = minimum viable product


25m then 5m break


3/25

CSS:


is for ID's


. is for classes
id is only used once, class can be used multiple times
float: left; goes left to right, right does the opposite


3/26

cmd+opt+j opens js console

3/27

cmd+shift+f is find for entire app

3/28

JS convention uses camelcase instead of snake case

3/31

cmd + r to search methods

4/1

server side javascript is node (can access files and folders)
client side javascript is the js that runs in chrome (can't access files and folders)
vue.js good framework to output js into html
use {{ }} similar to <%= %> in rails
webpack is awesome

4/2

rails db:setup = rails db:create && rails db:migrate && rails db:seed
rails db:reset drops db and runs above
=> (fat arrow) functions for axios

4/4

Nested DIVs are fine in Vue template, but consecutive divs are not
HOD: cntrl + A, go to beginning of line on terminal

4/7

HOD: cntrl + E, end of line terminal

4/8

cntrl + g searches by line

4/9

cntrl + shift + down highlight character directly below

4/10

cmd + j adds next line to end of current line

4/14

cmd + L : highlights entire line and moves cursor to beginning of next line

4/15

cntrl + m : toggles between beginning and ending curly braces