URL fields in serializers – Django REST Framework

07 Jan, 2022
In Django REST Framework the very concept of Serializing is to convert DB data to a datatype that can be used by javascript. Every serializer comes with some fields (entries) which are going to be processed. For example if you have a class with name Employee and its fields as Employee_id, Employee_name, is_admin, etc. Then, you would need AutoField, CharField and BooleanField for storing and manipulating data through Django. Similarly, serializer also works with same principle and has fields that are used to create a serializer. This article revolves around URL Fields in Serializers in Django REST Framework. There are two major fields – URLField and SlugField. 
URLField is basically a RegexField that validates the input against a URL matching pattern. Expects fully qualified URLs of the form http:///. It works the same as URLField – Django ModelsIt has the following arguments –  
allow_blank – If set to True then the empty string should be considered a valid value. If set to False then the empty string is considered invalid and will raise a validation error. Defaults to False.
Syntax –  
field_name = serializers.URLField(*args, **kwargs)
 
SlugField is a RegexField that validates the input against the pattern [a-zA-Z0-9_-]+. It is same as SlugField – Django Models.Syntax –  
field_name = serializers.SlugField(*args, **kwargs)
 
To explain the usage of URL Fields, let’s use the same project setup from – How to Create a basic API using Django Rest Framework ?. Now that you have a file called serializers in your project, let’s create a serializer with URLField and SlugField as the fields.  
Python3
# import serializer from rest_frameworkfrom rest_framework import serializers class Geeks(object):    def __init__(self, URL, slug):        self.URL = URL        self.slug = slug # create a serializerclass GeeksSerializer(serializers.Serializer):    # initialize fields    URL = serializers.URLField()    slug = serializers.SlugField()
Now let us create some objects and try serializing them and check if they are actually working, Run, –  
Python manage.py shell
Now, run following python commands in the shell  
# import everything from serializers
>>> from apis.serializers import *

# create a object of type Geeks
>>> obj = Geeks("https://www.geeksforgeeks.org/", "bring-out-the-geek-in-you-during-covid-19-outb
reak")

# serialize the object
>>> serializer = GeeksSerializer(obj)

# print serialized data
>>> serializer.data
{'URL': 'https://www.geeksforgeeks.org/', 'slug': 'bring-out-the-geek-in-you-during-covid-19-out
break'}
Here is the output of all these operations on terminal –  
 
Note that prime motto of these fields is to impart validations, such as URLField validates the data to URL only. Let’s check if these validations are working or not –  
# Create a dictionary and add invalid values
>>> data={}
>>> data['URL']="invalid_url"
>>> data['slug'] = "INVALID SLUG"

# dictionary created
>>> data
{'URL': 'invalid_url', 'slug': 'INVALID SLUG'}

# deserialize the data
>>> serializer = GeeksSerializer(data=data)

# check if data is valid
>>> serializer.is_valid()
False

# check the errors
>>> serializer.errors
{'URL': [ErrorDetail(string='Enter a valid URL.', code='invalid')], 
'slug': [ErrorDetail(string='Enter a valid "slug" consisting of letters, numbers,
underscores or hyphens.', code='invalid')]
}
Here is the output of these commands which clearly shows email and phone_number as invalid –  
 
Validations are part of Deserialization and not serialization. As explained earlier, serializing is process of converting already made data into another data type, so there is no requirement of these default validations out there. Deserialization requires validations as data needs to be saved to database or any more operation as specified. So if you serialize data using these fields that would work.  
 
.math-table { border-collapse: collapse; width: 100%; } .math-table td { border: 1px solid #5fb962; text-align: left !important; padding: 8px; } .math-table th { border: 1px solid #5fb962; padding: 8px; } .math-table tr>th{ background-color: #c6ebd9; vertical-align: middle; } .math-table tr:nth-child(odd) { background-color: #ffffff; } 
 
 
sweetyty
Django-REST
Python Django
rest-framework
Python
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