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Flask App Routing
2019-12-14 06:36:13

Flask App Routing

Routing

In order to help clients, modern web apps use URLs. Usually One like a website and revisit it if the page uses a easy URL that they can remember and use these URLs to access a webpage directly.

Routing  is the  way of  assigning URL to function  that contains view logic. We can route URL by  using decorator. A decorator is, whenever you have a function, and you see an @ symbol  at  the starting and the something like  (app.route('/')) after it. This "@app.route('/')" is the decorator . It basically a way that you can wrap up an existing Python  Function and  can modify its behavior in some  way that is as per user requirement .

With flask we use app  routing to route  or map  URL to return a value. We can say that  in routing   we are doing a complex terminology out of the way is we are connecting  a URL to  the return  value of a function.  So,  whenever a user  requests this URL the response from  the  server is going  to be whatever  this return  value  is right there in its definition.

To bind a function to a URL, One use the route(), decorator function.

For example, the URL (‘/’) is associate  with the home function that returns  a particular  string displayed  on the webpage in the browser

In other words, we can say that if a user visits the particular URL mapped to some specific function, the output of that function is displayed on the browser's screen.

Example

fromflaskimportFlask
app=Flask(__name__)
@app.route('/home')
defhome():
return"hello,welcometoourwebsite";
if__name__=="__main__":
app.run(debug=True)

Example

fromflaskimportFlask
app=Flask(__name__)
@app.route('/home/')
defhome(name):
return"hello,"+name;
if__name__=="__main__":
app.run(debug=True)

Let’s run this code using the commands that we already discussed previously.

Flask App Routing

We can make the dynamic parts of the URL  and attach multiple sets of rules to a function.

The converter can also be used in the URL to assign the specific variable to the specific data type. For example, we can assign the integers or the float, respectively, like age or salary.

For example

fromflaskimportFlask
app=Flask(__name__)
@app.route('/home/')
defhome(age):
return"Age=%d"%age;
if__name__=="__main__":
app.run(debug=True)

The given converters are used to convert the default string type to the corresponding data type.

  1. string: default
  2. int: used to convert the string to the integer
  3. float: used to convert the string to the float.
  4. path: It can accept the slashes given in the URL.

The output of this code is given below:-

Flask App Routing 1

The add_url_rule() function

There is another approach to route the globe web application that can be done using the function add_url()  of the Flask class. The syntax for using this function is shown below.

add_url_rule(<url rule>, <endpoint>, <view function>)  

This function is mainly used when the display function is not specified, and we must connect a display function to an endpoint externally using this function. 

fromflaskimportFlask
app=Flask(__name__)
defabout():
return"Thisisaboutpage";
app.add_url_rule("/about","about",about)
if__name__=="__main__":
app.run(debug=True)

Output 

Flask App Routing 2