# URL name
\
### 1. DB
#### DB initialization
1. Delete `db.sqlite3`
2. Delete `migration` files
#### Check `migration` files
```bash
python manage.py showmigrations
```
#### Create `migrations` again
```bash
python manage.py makemigrations
```
#### Output corresponding `SQL` statement
```bash
$ python manage.py sqlmigrate articles 0001
[app_label] [migration_name]
BEGIN;
--
-- Create model Article
--
CREATE TABLE "articles_article" ("id" integer NOT NULL PRIMARY KEY AUTOINCREMENT, "title" varchar(140) NOT NULL, "content" text NOT NULL, "created_at" datetime NOT NULL, "updated_at" datetime NOT NULL);
COMMIT;
```
#### Run `migrate`
```bash
$ python manage.py migrate
[app_label] [migration_name]
```
#### `create()`
> For creation, you can also do it as follows!
1.
```python
Article.objects.create(title='title', content='content')
```
2.
```python
article = Article(title='title', content='content')
article.save()
```
#### `IntegrityError`
: This exception is raised when the relational integrity of the data is affected.
\
### 2. `GET` & `POST` method
* GET
* Retrieve data
* **Display** of specific resources
* `` tag, `
```
> You can see that `csrf token` is added as a hidden value
#### Send simple request with Curl
```bash
curl -X GET http://chloecodes1.pythonanywhere.com/community/
```
#### Using Telnet
> Installation
```bash
sudo apt-get install telnetd
```
> Send request
```bash
telnet google.com 80
```
\
### 3. Specifying `app_name`
> urls.py
```python
from django.urls import path
from . import views
app_name = 'articles'
urlpatterns = [
# /articles/
path('', views.index, name='index'),
path('new/', views.new, name='new'),
path('create/',views.create, name='create'),
path('/',views.detail, name='detail'),
path('delete//',views.delete, name='delete'),
path('edit//', views.edit, name='edit'),
path('update//', views.update, name='update'),
]
```
> views.py
```python
from django.shortcuts import render, redirect, get_object_or_404
from .models import Article
# Create your views here.
def index(request):
articles = Article.objects.all()
context = {
'articles': articles
}
return render(request, 'articles/index.html', context)
def new(request):
return render(request, 'articles/new.html')
def create(request):
article = Article()
article.title= request.POST.get('title')
article.content = request.POST.get('content')
article.save()
# return redirect(f'/articles/{article.pk}/')
return redirect('articles:detail', article.pk)
def detail(request, pk):
article = Article.objects.get(id=pk)
context = {
'article':article
}
return render(request,'articles/detail.html', context)
def delete (request, pk):
article = Article.objects.get(id=pk)
article.delete()
# return redirect(f'/articles/')
return redirect('articles:index')
def edit(request, pk):
article = get_object_or_404(Article, id = pk)
context = {
'article': article
}
return render(request, 'articles/edit.html', context)
def update (request,pk):
article = Article.objects.get(id=pk)
article.title = request.POST.get('title')
article.content = request.POST.get('content')
article.save()
return redirect(f'/articles/{article.pk}/')
```
> In html
```html
...
...
```
\
### 4. get\_object\_or\_404
`article = Article.objects.get(id=pk)`
* get() raises error if value doesn't exist
* Method that returns only one
* So what we use is
```python
from django.shortcuts import render, redirect, get_object_or_404
...
article = get_object_or_404(Article, id=pk)
```
\
### 5. Static files
> settings.py
```python
# Attached in front of serving URL
STATIC_URL = '/static/'
# Specify static folder not in app directory
STATICFILES_DIRS = [
os.path.join(BASE_DIR, 'static')
]
```
\
\
`+`
### Traceroute
> `TraceRoute` - Linux / `TRACERT` - Windows
*A command that tracks the path information to reach a specified host and the delay time at each path, simply think of it as a path tracking tool (uses ICMP!)*
* A network command that tracks **path information** to reach a specified host and **delay time** at each path, useful for finding out where bottlenecks occur when *a specific site is not accessible or has delays*.
* By checking each path that gets connected, you can confirm **which path (Routing)** is used for connection, **how much** speed delay exists in **which section**, and **where** packets stopped
* However, values may vary due to many influences such as *time zone/internal traffic/server status*, so repeated confirmation is necessary!
> Install traceroute
```bash
sudo apt-get install traceroute
```
> Use traceroute
```bash
$ traceroute www.google.com
traceroute to www.google.com (172.217.31.164), 30 hops max, 60 byte packets
1 _gateway (172.30.1.254) 5.195 ms 5.127 ms 5.105 ms
2 220.78.3.1 (220.78.3.1) 5.071 ms * *
3 125.141.249.21 (125.141.249.21) 5.364 ms 5.308 ms 5.262 ms
4 * * *
5 * * *
6 112.174.73.178 (112.174.73.178) 6.510 ms 112.174.47.162 (112.174.47.162) 5.301 ms 112.174.73.178 (112.174.73.178) 4.858 ms
7 74.125.52.16 (74.125.52.16) 31.913 ms 31.801 ms 33.951 ms
8 108.170.242.129 (108.170.242.129) 36.142 ms 108.170.242.97 (108.170.242.97) 34.386 ms 34.811 ms
9 209.85.253.109 (209.85.253.109) 36.711 ms 36.555 ms 36.483 ms
10 nrt12s22-in-f4.1e100.net (172.217.31.164) 34.998 ms 33.267 ms 32.844 ms
```
\
### MVC Pattern
* model driven design
* data modeling