Using Flask - A step by step...

UNIVERSITY OF SCIENCE AND TECHNOLOGY OF CHINA SCHOOL OF SOFTWARE ENGINEERING OF USTC

Using FlaskA step by step demonstration

Devert Alexandre

January 5, 2013 — Slide 1/62


Table of Contents

1 Introduction

2 Starting minimal

3 Database integration

4 User’s links

5 Posting links

6 Ordering the links

Devert Alexandre — Using Flask — Slide 2/62


Objective

• Using Flask on a real application

• Showing how SQLAlchemy and Flask works together

• Demonstrating the power of a modern web applicationframework



Study case : LINKY

We will build LINKY, a social website

• Users can post links about they read on the web

• Users can see what are the lastest posted links

• Can see links of their friends, per category, etc.

Don’t laught : 10 years ago, it was the future . . .



Table of Contents

1 Introduction

2 Starting minimal


4 User’s links

5 Posting links




Objective

Objective of this step

Starting with a minimal but working and extensible code base



The file hiearchy

The file hierarchy

|− run . py||− s t a t i c| || |− base . c s s||− t emp l a t e s

||− base . html|− i n d e x . html



run.py

run.py is the script to use for starting our wep application

from f l a s k impor t F lask , r e n d e r t emp l a t eapp = F l a s k ( name )

@app . r ou t e ( ’ / ’ )d e f i nd e x ( ) :

r e t u r n r e n d e r t emp l a t e ( ’ i nd e x . html ’ )

i f name == ’ ma i n ’ :app . run ( debug = True )

• Instanciate the Flask application object

• The root URL serves a single page, index.html

• We run in debug mode



index.html

index.html is the welcome page for our website

{% extend s ” base . html ” %}

{% block con t en t %}<d i v c l a s s = ” s e c t i o n ”>

<h2>What i s i t ?</h2><p>L inky i s a web s i t e to sha r e l i n k s between f r i e n d s . Funny , amazing ,r e v o l t i n g , o r i n s p i r i n g , s ha r e them a l l ! Ju s t copy−pa s t e a l i n k , put acomment , and t h e r e you go , a l l your f r i e n d s w i l l s e e i t .</p>

</ d i v>

<d i v c l a s s = ” s e c t i o n ”><h2>How i t works ?</h2><p>Reg i s t e r , f o r f r e e , to ge t an account . Once l ogged in , you w i l l s e e themost popu l a r l i n k s . Add f r i e n d s , and you w i l l s e e t h e i r l i n k s too .</p>

</ d i v>{% endb lock %}



base.htmlAt this step, we already define a common template for all theviews : base.html

<!DOCTYPE HTML PUBLIC ”−//W3C//DTD HTML 4.01//EN”><html l ang=”en”>

<head>< t i t l e>LINKY</ t i t l e>< l i n k r e l=” s t y l e s h e e t ” type=” t e x t / c s s ” media=” s c r e e n ”

h r e f=”{{ u r l f o r ( ’ s t a t i c ’ , f i l e n ame=’ base . cs s ’ ) }}”></head><body>

<d i v i d=” c o n t a i n e r ”><d i v i d=” heade r ”>

<h1>LINKY</h1></ d i v>

<d i v i d=” con ten t ”>{% block con t en t %}{% endb lock %}

</ d i v></ d i v>

<d i v i d=” f o o t e r ”><h1>LINKY</h1><p>Des ign &amp ; c o p y r i g h t &copy ; A l exand re Dever t</p>

</ d i v></body>

</html>



base.css

base.css is the CSS style used for our website

html , body , d iv , span , h1 , h2 , h3 , h4 , h5 , h6 , p {margin : 0 ;padd ing : 0 ;bo rde r : 0 ;font−s i z e : 100%;f o n t : i n h e r i t ;v e r t i c a l−a l i g n : b a s e l i n e ;

}

body {f o n t : h e l v e t i c a , a r i a l , sans−s e r i f ;c o l o r : DarkS la teGray ;background−c o l o r : Co r nS i l k ;l i n e−h e i g h t : 1 ;

}

. . .

Getting the CSS to look right takes a LOT of time . . .



The main pageWhat we have done so far, from user point of view

The minimal style is deliberate : at first, don’t waste time onwhat will change a lot



Conclusion

• Minimal code

• Define the common template for all views ⇒ coherentstyle for all our views, no code duplication

• Heavy use of the div tag ⇒ full control on the graphicstyle

• Minimal graphic style, just keep it open and easy tochange



Table of Contents

1 Introduction

2 Starting minimal


4 User’s links

5 Posting links




Objective


• Putting together Flask and SQLAlchemy

• Setting the User table

• Allowing users to login and logout



The file hiearchy

The file hierarchy

|− db−i n i t . py||− l i n k y| |− database . py| |− i n i t . py| |− model . py||− run . py||− s t a t i c| |− base . c s s| |− form . c s s| |− pane l . c s s||− t emp l a t e s| |− base . html| |− home . html| |− i n d e x . html| |− l o g i n . html| |− u i . html||− u s e r s . t x t



The file hiearchy

Note that we define a linky Python module

|− l i n k y| |− database . py| |− i n i t . py| |− model . py

• init .py is just to tell Python that linky is a module.

• model.py will contain all the objects of the Linky datamodel

• database.py Contains the declaration and definitions forSQLAlchemy



database.py

database.py is exactly as we had it in the ORM mappingtutorial

from sq l a l ch emy impor t c r e a t e e n g i n efrom sq l a l ch emy . orm impor t s e s s i onmake r , s c o p e d s e s s i o nfrom sq l a l ch emy . e x t . d e c l a r a t i v e impor t d e c l a r a t i v e b a s e

Base = d e c l a r a t i v e b a s e ( )

d b f i l e n ame = ’ l i n k y . db ’eng i n e = c r e a t e e n g i n e ( ’ s q l i t e :///% s ’ % db f i l e n ame , echo = Fa l s e )d b s e s s i o n = s c o p e d s e s s i o n ( s e s s i onmake r ( b ind = eng i n e ) )

de f d b i n i t ( ) :from . impor t modelBase . metadata . c r e a t e a l l ( b ind = eng in e )



The User object

The user table

name SQL type

id INTEGER

name VARCHAR(256)

email VARCHAR(256)

pwd hash VARCHAR(128)

pwd salt VARCHAR(48)

We do not store passwords in clean, we store hashed andsalted passwords. It’s basic security standard.



The User object

We use SQLAlchemy to have an object User mapped to theuser table

c l a s s User ( Base ) :t a b l e n ame = ’ u s e r ’

i d = Column ( I n t e g e r , p r ima r y k e y = True )name = Column ( S t r i n g (256 ) )ema i l = Column ( S t r i n g (256 ) )pwd hash = Column ( S t r i n g (128 ) )pwd sa l t = Column ( S t r i n g (48 ) )

User is part of the our model for Linky, so it goes in model.py



The User object

A few useful methods for our User object

de f i n i t ( s e l f , name , ema i l ) :s e l f . name = names e l f . ema i l = ema i l

d e f hash pas sword ( s e l f , password , s a l t ) :r e t u r n h a s h l i b . sha512 ( s a l t + password ) . h e x d i g e s t ( )

de f s e t p a s swo rd ( s e l f , password ) :s e l f . pwd sa l t = base64 . b64encode ( os . urandom (32 ) )s e l f . pwd hash = s e l f . hash pas sword ( password , s e l f . pwd sa l t )

d e f check pas sword ( s e l f , password ) :r e t u r n s e l f . pwd hash == s e l f . hash pas sword ( password , s e l f . pwd sa l t )

• We use SHA512, a up-to-date cryptographic hash

• The hash is stored in hexadecimal coding

• All the password handling is done in User



Creating a test database

To make tests, it is good to have a test database.

Alex marmakoide@yahoo . f r a l e xThomas tweise@gmx . de thomasWei tangwe i@hotma i l . com weiXiang n c x a l i c e@ho tma i l . con x i ang

users.txt contains some fake user account definitions.




The script db-init.py reads a text file and creates a newdatabase with the users defined in the text file

d b i n i t ( )

t r y :f o r l i n e i n a r g s . i n p u t f i l e :

l i n e = l i n e . s t r i p ( )i f l e n ( l i n e ) == 0 :

con t i nu e

tokens = l i n e . s p l i t ( )u s e r = User ( tokens [ 0 ] , t okens [ 1 ] )u s e r . s e t p a s swo rd ( tokens [ 2 ] )d b s e s s i o n . add ( u s e r )

e x cep t Va l u eE r r o r as e :s y s . s t d e r r . w r i t e ( ’ E r r o r wh i l e r e a d i n g ”%s”\n ’ % a rg s . i n p u t f i l e . name )s y s . s t d e r r . w r i t e ( ’%s\n ’ % e )s y s . e x i t ( 0 )

d b s e s s i o n . commit ( )

Reading the file and adding elements to the User table





# Command−l i n ep a r s e r = a r gp a r s e . ArgumentParser ( d e s c r i p t i o n = ’ Popu la te a da tabase from a t e x t f i l e ’ )p a r s e r . add argument ( ’ i n p u t f i l e ’ , t ype = a r gpa r s e . F i l eType ( ’ r ’ ) , d e f a u l t = s y s . s t d i n , h e l p = ’ a l i s t o f u s e r s ’ )a r g s = pa r s e r . p a r s e a r g s ( )

# De l e t e the db dump i f i t e x i s t si f os . path . e x i s t s ( d b f i l e n ame ) :

os . remove ( d b f i l e n ame )

We take the path of the input text file from command-line





impor t os , os . path , sys , a r g p a r s e

from l i n k y . da tabase impor t db f i l e n ame , d b i n i t , d b s e s s i o nfrom l i n k y . model impor t User

And of course, we need to import the proper definitions



The main user page

The run.py now contain a new URL : home, the main pagefor one user.

de f c h e c k u s e r i s l o g g e d ( ) :# Send ’ Unautho r i z ed ’ i f no u s e r l ogged i ni f g . u s e r i s None :

abo r t (401)

@app . r ou t e ( ’ /home ’ )de f home ( ) :

c h e c k u s e r i s l o g g e d ( )r e t u r n r e n d e r t emp l a t e ( ’ home . html ’ , u s e r = g . u s e r )



The main user page

The main page of a user, home.html, is kept to a bareminimum for now

{% extend s ” base . html ” %}

{% block con t en t %}<d i v c l a s s=” s i n g l e−column−l a you t−25”>

<d i v c l a s s=”middle−column”><d i v c l a s s = ” s e c t i o n ”>

<h2>Welcome , {{ u s e r . name }} !</h2></ d i v>

</ d i v></ d i v>{% endb lock %}

We of course extends base.html



The main user page

The logging page



Logging in

Logging in is a fairly complex affair

@app . r ou t e ( ’ / l o g i n ’ , methods = ( ’GET ’ , ’POST ’ ) )de f l o g i n ( ) :

# POST r e qu e s ti f r e q u e s t . method == ’POST ’ :# Try to f i n d the u s e rt r y :

u s e r = d b s e s s i o n . query ( User ) . f i l t e r ( User . ema i l == r e qu e s t . form [ ’ ema i l ’ ] ) . one ( )excep t sq l a l ch emy . orm . exc . NoResultFound :

e r r o r = ’ Thi s ema i l have not be r e g i s t e r e d ’r e t u r n r e n d e r t emp l a t e ( ’ l o g i n . html ’ , u s e r = g . use r , e r r o r = e r r o r )

# Check the u s e r passwordi f not u s e r . check pas sword ( r e q u e s t . form [ ’ password ’ ] ) :

e r r o r = ’Wrong password ’r e t u r n r e n d e r t emp l a t e ( ’ l o g i n . html ’ , u s e r = g . use r , e r r o r = e r r o r )

# Job dones e s s i o n [ ’ u s e r i d ’ ] = u s e r . i dr e t u r n r e d i r e c t ( u r l f o r ( ’ home ’ ) )

# GET Requeste l s e :

r e t u r n r e n d e r t emp l a t e ( ’ l o g i n . html ’ , u s e r = g . u s e r )



Logging in

Logging can send informations (the logging page) and receiveinformations (the logging informations)

@app . r ou t e ( ’ / l o g i n ’ , methods = ( ’GET ’ , ’POST ’ ) )de f l o g i n ( ) :

i f r e q u e s t . method == ’POST ’ :. . .

e l s e :r e t u r n r e n d e r t emp l a t e ( ’ l o g i n . html ’ , u s e r = g . u s e r )



Logging in

The logging page



Logging in

The logging page, after a logging error



Logging inThe logging page, login.html, defines a form with two fields

{% extend s ” base . html ” %}{% impor t ” u i . html ” as u i %}


<d i v c l a s s=”middle−column”>{%− c a l l u i . r e n d e r p a n e l ( ” Log in ” , ” c e n t e r ” ) −%}<form name=” l o g i n ” method=” pos t ” a c t i o n=”{{ u r l f o r ( ’ l o g i n ’ ) }}”>

< l a b e l>Emai l</ l a b e l><i n pu t type=” t e x t ” name=” ema i l ” maxlength=”254”/>

< l a b e l>Password</ l a b e l><i n pu t type=”password ” name=”password ”/>

<button type=” submit ”>Ente r</ button></ form>{% i f e r r o r i s d e f i n e d %}<hr /><p>{{ e r r o r }}</p>{% end i f %}{%− e n d c a l l %}




Logging in

Once the user press enter, the loggin information arePOSTed and processed

# POST r e qu e s ti f r e q u e s t . method == ’POST ’ :# Try to f i n d the u s e rt r y :

u s e r = d b s e s s i o n . query ( User ) . f i l t e r ( User . ema i l == r e qu e s t . form [ ’ ema i l ’ ] ) . one ( )excep t sq l a l c h emy . orm . exc . NoResultFound :

e r r o r = ’ Thi s ema i l have not be r e g i s t e r e d ’r e t u r n r e n d e r t emp l a t e ( ’ l o g i n . html ’ , u s e r = g . use r , e r r o r = e r r o r )

# Check the u s e r passwordi f not u s e r . check pas sword ( r e q u e s t . form [ ’ password ’ ] ) :

e r r o r = ’Wrong password ’r e t u r n r e n d e r t emp l a t e ( ’ l o g i n . html ’ , u s e r = g . use r , e r r o r = e r r o r )

# Job dones e s s i o n [ ’ u s e r i d ’ ] = u s e r . i dr e t u r n r e d i r e c t ( u r l f o r ( ’ home ’ ) )



Logging in

When trying to loggin in

1 Check that the users exists. If not, signal it.

2 Check that the password is correct. If not, signal it.

3 Create a user id session cookie variable, to keep track ofthe connected user.

4 Redirect to the user homepage



Logging out

Logging out is a fairly simple control

@app . r ou t e ( ’ / l o gou t ’ )d e f l o gou t ( ) :

s e s s i o n . pop ( ’ u s e r i d ’ , None )r e t u r n r e d i r e c t ( u r l f o r ( ’ i nd e x ’ ) )

• We associate this control to thelogout URL

• We remove the user id variable from the session

• We redirect the user to the default introduction page



Additional magic

We also defines the following methods

@app . b e f o r e r e q u e s tde f b e f o r e r e q u e s t ( ) :

# Ensure we got a u s e r i n s t a n c e i f the u s e r i s l ogged i ng . u s e r = Nonei f ’ u s e r i d ’ i n s e s s i o n :

g . u s e r = db s e s s i o n . query ( User ) . f i l t e r ( User . i d == s e s s i o n [ ’ u s e r i d ’ ] ) . one ( )

Before processing any request we make sure we have theright User instance



Additional magic

We also defines the following methods

@app . t e a r down r eque s tde f s hu t down s e s s i o n ( e x c e p t i o n = None ) :

d b s e s s i o n . remove ( )

We cleanup the with the database session once a request isprocessed



Additional magic

ui.html defines useful reusable user interface elements

{%− macro r e n d e r p a n e l ( t i t l e , s t y l e=” l e f t ” ) %}<d i v c l a s s=” pane l ”>

<h1 c l a s s=”{{ s t y l e }}”>{{ t i t l e }}</h1><d i v c l a s s=” pane l−con t en t ”>

<d i v c l a s s=”{{ s t y l e }}”>{{ c a l l e r ( ) }}

</ d i v></ d i v>

</ d i v>{%− endmacro %}



The root page

The root page have now a button for logging in and register



The root page

This is done with a tags and a bit of CSS in index.html

<d i v c l a s s = ”menu”><u l>

< l i><a h r e f=”{{ u r l f o r ( ’ l o g i n ’ ) }}”>Log in</a></ l i>< l i><a h r e f=”{{ u r l f o r ( ’ l o g i n ’ ) }}”>Re g i s t e r</a></ l i>

</ u l></ d i v>



Conclusion

• We have now one model (User), some views and somecontroller

• Users can login and logout

• Database and session management



Table of Contents

1 Introduction

2 Starting minimal


4 User’s links

5 Posting links




Objective


• Define the Link object

• Showing all the links

• Showing the links for one user



The Link object

The link table

name SQL type

id INTEGER

url VARCHAR(1024)

comment VARCHAR(1024)



The Link object

We use SQLAlchemy to have an object Link mapped to thelink table

c l a s s L ink ( Base ) :t a b l e n ame = ’ l i n k ’

i d = Column ( I n t e g e r , p r ima r y k e y = True )u r l = Column ( S t r i n g (1024) )comment = Column ( S t r i n g (1024) )

de f i n i t ( s e l f , u r l ) :s e l f . u r l = u r l

Link is part of the our model for Linky, so it goes inmodel.py, like for User



The Link object

We also have to modelize the relationship between Link andUser : it’s a one-to-many relationship.In the User class

l i n k s = r e l a t i o n s h i p ( ’ L ink ’ , b a c k r e f = ’ u s e r ’ )

In the Link class

u s e r i d = Column ( I n t e g e r , Fore ignKey ( ’ u s e r . i d ’ ) )



The user’s home page

The user’s home page, home.html, displays a list of linksnamed linked list



<d i v c l a s s=”middle−column”><d i v c l a s s = ”menu”>

<u l>< l i><a h r e f=”{{ u r l f o r ( ’ l ogout ’ ) }}”>Logout</a></ l i>

</ u l></ d i v>

<h2>The l a t e s t l i n k s</h2>{% f o r l i n k i n l i n k l i s t %}{{ u i . r e n d e r p o s t ( l i n k ) }}

{% end f o r %}</ d i v>


The HTML code for a posted link is done by ui.render post



The user’s home page

The controler that renders home.html provides linked list

@app . r ou t e ( ’ /home ’ )de f home ( ) :

c h e c k u s e r i s l o g g e d ( )

l i n k s = db s e s s i o n . query ( L ink ) . a l l ( )r e t u r n r e n d e r t emp l a t e ( ’ home . html ’ , u s e r = g . use r , l i n k l i s t = l i n k s )

Later, we might want to render only some of the links, say,the 20 first ones, only from friends.



Rendering a posted link

ui.render post is defined in ui.html

{%− macro r e n d e r p o s t ( l i n k ) %}<d i v c l a s s=” pos t ”>

<h1>{{ l i n k . comment }}</h1><d i v c l a s s=” pane l−con t en t ”>

<a h r e f=”{{ l i n k . u r l }}”>{{ l i n k . u r l }}</a><p>

pos ted by<a h r e f=”{{ u r l f o r ( ’ show user ’ , name=l i n k . u s e r . name ) }}”>{{ l i n k . u s e r . name }}</a>

</p></ d i v>

</ d i v>{%− endmacro %}

Very easy to reuse, no code duplication, and style completlycontroled by CSS



Showing all posts from user

We define user.html, a page that shows post from one user



<d i v c l a s s=”middle−column”><d i v c l a s s = ”menu”>

<u l>< l i><a h r e f=”{{ u r l f o r ( ’ home ’ ) }}”>Home</a></ l i>

</ u l></ d i v>

<h2>L i nk s from {{ owner . name }}</h2>{% f o r l i n k i n owner . l i n k s %}{{ u i . r e n d e r p o s t ( l i n k ) }}

{% e l s e %}{{ owner . name }} d id not pos t l i n k s y e t . . .

{% end f o r %}</ d i v>


owner is the User instance whom post are shown




The corresponding controller in run.py

@app . r ou t e ( ’ / u s e r/<name>’ )d e f show use r ( name ) :


# Check i f the u s e r e x i s t st r y :

owner = db s e s s i o n . query ( User ) . f i l t e r ( User . name == name ) . one ( )excep t sq l a l c h emy . orm . exc . NoResultFound :

abo r t (404)

# Show the page f o r t ha t u s e rr e t u r n r e n d e r t emp l a t e ( ’ u s e r . html ’ , u s e r = g . use r , owner = owner )

If the user does not exist, we raise an error 404 (Not Found)




The corresponding controller in run.py

@app . r ou t e ( ’ / u s e r/<name>’ )d e f show use r ( name ) :


# Check i f the u s e r e x i s t st r y :

owner = db s e s s i o n . query ( User ) . f i l t e r ( User . name == name ) . one ( )excep t sq l a l c h emy . orm . exc . NoResultFound :

abo r t (404)

# Show the page f o r t ha t u s e rr e t u r n r e n d e r t emp l a t e ( ’ u s e r . html ’ , u s e r = g . use r , owner = owner )

We use a parametric URL. /user/SunWuKong will show thelinks posted by the user named SunWuKong



Generating the test database

We still need a simple way to generate a test database, withdb-init.py

• A simple text format

• Contains fake users

• Contains fake posted links from users

Use JSON file, it’s very easy to parse in Python, with thejson module




A sample of the JSON file

{” u s e r s ” : [{

”name” : ” Alex ” ,” ema i l ” : ”marmakoide@yahoo . f r ” ,”pwd” : ” a l e x ” ,” l i n k s ” : [{

” u r l ” : ” h t tp : //www. pouet . net ” ,”comment” : ” Stay i n tune wi th the demoscene ! ”

} ,{

” u r l ” : ” h t tp : // theoatmea l . com/ comics / dog paradox ” ,”comment” : ”Ha ha , my dog the same”

}}

]}




Reading the JSON file is one line of code

db data = j s o n . l oad ( ’my−f i l e . j s ’ )

This returns a structure that reflects the content of the file




Then, we just traverse the returned structure and builddatabase objects

f o r u s e r d a t a i n db data [ ’ u s e r s ’ ] :# Crea te the u s e r i n s t a n c eu s e r = User ( u s e r d a t a [ ’ name ’ ] , u s e r d a t a [ ’ ema i l ’ ] )u s e r . s e t p a s swo rd ( u s e r d a t a [ ’ pwd ’ ] )

# Add each l i n ki f ’ l i n k s ’ i n u s e r d a t a :

f o r l i n k d a t a i n u s e r d a t a [ ’ l i n k s ’ ] :l i n k = L ink ( l i n k d a t a [ ’ u r l ’ ] )i f ’ comment ’ i n l i n k d a t a :

l i n k . comment = l i n k d a t a [ ’ comment ’ ]u s e r . l i n k s . append ( l i n k )

# Add the u s e rd b s e s s i o n . add ( u s e r )



Conclusion

• The model have one new object, Link

• The home page show all the links posted

• We have a page to show all posts from one user



Table of Contents

1 Introduction

2 Starting minimal


4 User’s links

5 Posting links




Objective


• A new view to post links



A new view : post.htmlWe define a new view, post.html : the form to post a link



<d i v c l a s s=”middle−column”>{%− c a l l u i . r e n d e r p a n e l ( ” Log in ” , ” c e n t e r ” ) −%}<form name=” pos t ” method=” pos t ” a c t i o n=”{{ u r l f o r ( ’ p o s t l i n k ’ ) }}”>

< l a b e l>Link ’ s URL</ l a b e l><i n pu t type=” t e x t ” name=” u r l ” maxlength=”1024”/>

< l a b e l>Comment</ l a b e l><i n pu t type=” t e x t ” name=”comment” , maxlength=”1024”/>

<button type=” submit ”>Ente r</ button></ form>{% i f e r r o r i s d e f i n e d %}<hr /><p>{{ e r r o r }}</p>{% end i f %}{%− e n d c a l l %}




The link posting controller

In run.py we define a new URL : the link posting controller

@app . r ou t e ( ’ / pos t ’ , methods = ( ’GET ’ , ’POST ’ ) )de f p o s t l i n k ( ) :


# POST r e qu e s ti f r e q u e s t . method == ’POST ’ :# Crea te the l i n kl i n k = Link ( r e q u e s t . form [ ’ u r l ’ ] )l i n k . comment = r e qu e s t . form [ ’ comment ’ ]l i n k . u s e r = g . u s e r

# Update dbd b s e s s i o n . add ( l i n k )d b s e s s i o n . commit ( )r e t u r n r e d i r e c t ( u r l f o r ( ’ home ’ ) )

# GET Requeste l s e :

r e t u r n r e n d e r t emp l a t e ( ’ po s t . html ’ , u s e r = g . u s e r )



Access to the link posting view

We have now to give a simple way to access to the linkposting view.

<d i v c l a s s = ”menu”><u l>

< l i><a h r e f=”{{ u r l f o r ( ’ p o s t l i n k ’ ) }}”</a>New l i n k</ l i>< l i><a h r e f=”{{ u r l f o r ( ’ l ogout ’ ) }}”>Logout</a></ l i>

</ u l></ d i v>

In home.html, we put a button that link to link posting view.



Conclusion

• We added a new view and a new controller

• The changes were additions

• No changes to previous code



Table of Contents

1 Introduction

2 Starting minimal


4 User’s links

5 Posting links




Objective


• Links should store the date of the post

• Links should be shown ordered by date


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