Add Authentication to an Image Blog in Web2py

Add Images to the Web2py Blog

So now, in this section, we will discuss how to add images to the web2py blog. So before going into anything, let us start from scratch. Start the executable file for Web2py. Now start the server by choosing the password to your network. As shown below.

Web2Py Server Login

Once you click on start server, it will open /welcome/default/index in our web browser. Similar to the screen displayed below

Web2py Default Welcome Window

Now we are all set to start working on the web2py framework. So next step is to get a detailed understanding of how to add images to the web2py blog.

First, create a new application called CodingNinjaImage, and navigate to the edit page.

Web2py Administration Login

 

Installed Applications

So now, we will create a model representing the persistent data in the application. Create/edit a model file called "db.py" for lack of imagination. Remove the model "menu.py". Corresponding to the "db.py" file, there is an "edit" button.

 

Edit Window Web2Py

Click on the edit button mentioned above and enter the below code into that file. 

db = DAL("sqlite://storage.sqlite")
# Above Line defines a global variable called db that represents the database connection.For above case its an connection to SQLite database


# Here we have defined a table called "image". Method define_table of the db object is used. The first argument of define_table, "image", is the name of the table
db.define_table('image',
                Field('title', unique=True),
                Field('file', 'upload'),
                format = '%(title)s')


# Here we have defined a table called "post". Method define_table of the db object is used. The first argument of define_table, "post", is the name of the table
db.define_table('post',
                Field('image_id', 'reference image'),
                Field('author'),
                Field('email'),
                Field('body', 'text'))


# Validators
# Validator for Title of Image
db.image.title.requires = IS_NOT_IN_DB(db, db.image.title)
# Validator for Image ID
db.post.image_id.requires = IS_IN_DB(db, db.image.id, '%(title)s')
# Validator for author requirement
db.post.author.requires = IS_NOT_EMPTY() # author could not be empty
# Validator for email requirement
db.post.email.requires = IS_EMAIL()
# Validator for body requirement
db.post.body.requires = IS_NOT_EMPTY()


db.post.image_id.writable = db.post.image_id.readable = False

Once we have defined a model and there are no errors, web2py creates an application administration interface to manage the database, which we can access directly via the "database administration" link on the edit page.

Application Databases

This interface is coded in the controller "appadmin.py" and the corresponding view "appadmin.html."If we edit the model and access appadmin again, web2py will generate a SQL file for altering the existing tables. Generated SQL is logged into the "sql.log".We need to go back to our appadmin and should try to insert a new image record.

Creating New Image Record

If we do not get a view, we need to render the dictionary by "views/generic.html" and Proceed by creating a view for our index action. also, edit "default/index.html" in admin, and replace its content with the following

{{extend 'layout.html'}}
<h1>Current Images</h1>
<ul>
{{for image in images:}}
{{=LI(A(image.title, _href=URL("show", args=image.id)))}}
{{pass}}
</ul>

 

Image Added to Database

Now, look back to the edit page and edit the "default.py" controller file to replace its contents with the code following.

def index():
    # get imags
    images = db().select(db.image.ALL, orderby=db.image.title)
    return dict(images=images)

We need to Proceed with creating a view for the index action. So Return to admin, edit "default/index.html" and replace its content with the below file code:

{{extend 'layout.html'}}
<h1>Current Images</h1>
<ul>
{{for image in images:}}
{{=LI(A(image.title, _href=URL("show", args=image.id)))}}
{{pass}}
</ul>

LInk to the Added Image

After clicking on the image name link, we are directed to http://127.0.0.1:8000/CodingNinjaImage/default/show/1, which results in an error since the action called "show" is not created in the controller file "default.py".

Invalid Request

So to get the view, let's edit the "default.py" controller by replacing its content with the below code:

def index():
    # To select all imags from the database and index them
    images = db().select(db.image.ALL, orderby=db.image.title)
    return dict(images=images)

def show():
    image = db.image(request.args(0, cast=int)) or redirect(URL('index'))
    db.post.image_id.default = image.id
    form = SQLFORM(db.post)
    if form.process().accepted:
        response.flash = 'your comment is posted'
    comments = db(db.post.image_id == image.id).select(orderby=db.post.id)
    # Return dictionary with image,comments and form
    return dict(image=image, comments=comments, form=form)

def download():
    # This function response to download action
    return response.download(request, db)

The "default.py" file of the controller in the scaffolding application already defines the "download" action. We will create a new view  "default/show.html".So you need to edit the new file and replace its content with the following code:

{{extend 'layout.html'}}
<h1>Image: {{=image.title}}</h1>
<div style="text-align:center">
<img width="200px"
     src="{{=URL('download', args=image.file)}}" />
</div>
{{if len(comments):}}
  <h2>Comments</h2><br /><p>
  {{for post in comments:}}
    <p>{{=post.author}} says <i>{{=post.body}}</i></p>
  {{pass}}</p>
{{else:}}
  <h2>No comments posted yet</h2>
{{pass}}
<h2>Post a comment</h2>
{{=form}}

Now our view will be able to display the image. file by calling the "download" action that is defined inside an <img ... /> tag. If any comments are found, it would loop over them and display each.

Look into the image to see how everything will appear to a visitor.

Final Result 

Authentication to an Image Blog in Web2py

Now, if we need to add Authentication to an image blog, the web2py API for Role-Based Access Control is quite sophisticated, So we are limiting ourselves to restricting access to the show action to authenticated users,

To limit web application access only to authenticated users, we need to add Authentication to an image blog which could be done in three steps. In our model, "db.py", we would add:

from gluon.tools import Auth
auth = Auth(db) 
auth.define_tables(username=True)

But we would also need to add one more action in our controller:

def user():
    return dict(form=auth())

The above two functions are sufficient to enable register, login, logout, etc., pages. which are enough to add authentication to an image blog . Our default layout will also show options for the corresponding pages in the top right corner.

Login Screen

We could also decorate these functions to whomsoever we want to restrict, for example.

@auth.requires_login()
def show():
    ...

Any attempt to access http://127.0.0.1:8000/CodingNinjaImageBlog/default/show/[image_id] will require a login. If the user is not login in already, It will redirect the user to http://127.0.0.1:8000/CodingNinjaImageBlog/default/user/login.

 

Login Authentication Page

Error Displayed While Invalid Access 

Since the user is not registered, we must sign up and log in.

User Registration Application Page

Once the user is registered they could log in to the web application and could post images and comments on the blog

Valid User Logged In

Among many other functions, The user function also exposes the following actions:

http://127.0.0.1:8000/CodingNinjaImageBlog/default/user/logout
http://127.0.0.1:8000/CodingNinjaImageBlog/default/user/register
http://127.0.0.1:8000/CodingNinjaImageBlog/default/user/verify_email
http://127.0.0.1:8000/CodingNinjaImageBlog/default/user/profile
http://127.0.0.1:8000/CodingNinjaImageBlog/default/user/retrieve_username
http://127.0.0.1:8000/CodingNinjaImageBlog/default/user/retrieve_password
http://127.0.0.1:8000/CodingNinjaImageBlog/default/user/request_reset_password
http://127.0.0.1:8000/CodingNinjaImageBlog/default/user/change_password
http://127.0.0.1:8000/CodingNinjaImageBlog/default/user/impersonate
http://127.0.0.1:8000/CodingNinjaImageBlog/default/user/not_authorized

So if there is any first-time user, they require to get register first to be able to login into the blog application. The application also already illustrates the auth object and the user function. The auth object is highly customizable and could also deal with registration permissions, CAPTCHA, email verification, and alternate login methods via plugins.

Also see, How to Check Python Version in CMD

Frequently Asked Questions

What is Web2py?

Web2Py is an open-source, free full-stack framework written in Python that helps rapidly develop fast, scalable, secure and portable database-driven web-based applications.

For what purpose Web2py is used?

Web2py is mainly used to program dynamic websites using Python as a programming language. It contains all the tools, components, and APIs essential to building a fully functional web application.

Which is easier, Web2py or Django?

Web2py differs from Django since it's very compact and easier to learn. Unlike Django, it doesn't have any project-level configuration file.

Web2py Support which version of Python?

Web2Py is compatible with both versions of Python, i.e., python 2. X and Python 3. X

Conclusion

In this article, we have learned how to add Authentication to an image blog in the web2py and briefly explored some basic introductions on web2py with the code execution. Now We expect you to know how to add images to the web2py blog and how to add Authentication to an image blog. Give an upvote to the blog to help other ninjas grow.

Also, visit our Guided Path in  Coding Ninjas Studio to learn about Web2py. If you are preparing for an interview, visit our Interview Experience Section and interview bundle for placement preparations. Upskill yourself in Python, Kivy, Backend Web Technologies, SQL, MongoDB, Data Structures and Algorithms, JavaScript,  System Design and much more!. Please upvote our blogs if you find them engaging and helpful! I wish you all the best for your future adventures and Happy Coding. 

Useful links: Web2py, Kivy, Ruby vs Python. You could also refer to the Web2py Introduction, Web2py Installation,  Web2py Application, Web2py Tool,  Web2py Capacity Planning and Troubleshooting in Web2py.