Validate field input using django serializer - django

Question

I have a field code in my Django model.
I have to check if the input string has the following properties:
Length should be 5 characters
1st & 2nd characters should be alphabets
3rd & 4th characters should be numbers
5th character should be E or N
I have a serializer as shown below which satisfies the first condition.
class MyModelSerializer(serializers.ModelSerializer):
code = serializers.CharField(max_length=5, min_length=5)
class Meta:
model = MyModel
fields = '__all__'
How can I fulfil the remaining conditions?

Answer 1

The remaining conditions can be fulfilled by adding a custom validator and using regex.
import re
class MyModelSerializer(serializers.ModelSerializer):
code = serializers.CharField(max_length=5, min_length=5)
def validate_code(self, value):
# check if the code matches the required pattern
pattern = r'^[A-Za-z]{2}\d{2}[EN]$'
if not re.match(pattern, value):
raise serializers.ValidationError('Code does not match required format')
return value
The name of the function validate_code is not mandatory in the serializer. You can name it whatever you like, as long as it starts with the word "validate" and takes in a value argument. The value argument represents the value of the field being validated.
Here is a bit of in-depth info about the regex pattern used above.
1st & 2nd characters should be alphabets:
[A-Za-z]{2} matches any two alphabetical characters, ensuring that the first and second characters are alphabet
3rd & 4th characters should be numbers:
\d{2} matches any two numeric characters, ensuring that the third and fourth characters are numbers
5th character should be E or N:
[EN] matches either E or N, ensuring that the fifth character is either E or N