DRF learning notes (I): Data Serialization

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Get ready

1. Create an

First create an application under the project root directory ：

python manage.py startapp demo

stay settings.py Add created app

INSTALLED_APPS = [
    'rest_framework',
     'demo',
]

2. establish model

stay demo In the catalog models.py Add the following code ：

from django.db import models

# Create your models here.
class ClassInfo(models.Model):
    number = models.IntegerField(verbose_name=' Class number ')
    grade = models.CharField(verbose_name=' grade ', max_length=3)

class StudentInfo(models.Model):
    name = models.CharField(max_length=10, verbose_name=' full name ')
    sex = models.CharField(max_length=1, verbose_name=' Gender ')
    from_class = models.ForeignKey(ClassInfo, on_delete=models.CASCADE)

Enter the following command in the project root directory to migrate ：

python manage.py makemigrations
python manage.py migrate

The following results show that the data migration is successful ：

1、 Define serializer

In order to model Data is serialized and deserialized , The corresponding model Provide a serializer , stay demo Create one in the directory serializers.py, First give ClassInfo Add a serializer ：

from rest_framework import serializers

class ClassInfoSerializer(serializers.Serializer):
    """ Class data serializer """
    id = serializers.IntegerField(label='ID', read_only=True)
    number = serializers.IntegerField(label=' Class number ')
    grade = serializers.CharField(label=' grade ', max_length=3)

2、 Use serializer

For convenience , We will be in django shell Use in , Enter the following command in the project root directory ：

python manage.py shell

1、 First insert a piece of test data

>>> from demo.models import ClassInfo
>>> ClassInfo.objects.create(number=1, grade=" Third grade ")

2、 Get the data object

>>> class_data = ClassInfo.objects.get(id=1)

3、 Build the serializer object and get the data

>>> from demo.serializers import ClassInfoSerializer
>>> serializer = ClassInfoSerializer(class_data)
>>> serializer.data

result ：

Be careful ： If you want to serialize a query set that contains multiple pieces of data QuerySet, You can do it by adding many=True Supplementary description of parameters

>>> ClassInfo.objects.create(number=1, grade=" second grade ")
<ClassInfo: ClassInfo object (2)>
>>> ClassInfo.objects.create(number=1, grade=" In grade one ")
<ClassInfo: ClassInfo object (3)>
>>> class_list = ClassInfo.objects.all()
>>> serializer = ClassInfoSerializer(class_list, many=True)
>>> serializer.data

result ：

3、 Associated object serialization

When the object to be serialized contains foreign keys , Need to use PrimaryKeyRelatedField Field associations are serialized as the primary key of the associated object . stay serializers.py add to StudentInfo serializers ：
Student serializer :

class StudentInfoSerializer(serializers.ModelSerializer):
    """ Student data serializer """
    id = serializers.IntegerField(label='ID', read_only=True)
    name = serializers.CharField(label=' full name ', max_length=10)
    sex = serializers.CharField(label=' Gender ', max_length=1)
    from_class = serializers.PrimaryKeyRelatedField(label=' The book ', read_only=True)

Use ：

>>> from demo.models import StudentInfo
>>> class_data = ClassInfo.objects.get(id=1)
>>> StudentInfo.objects.create(name=" Zhang San ", sex=" male ", from_class = class_data)
>>> from demo.serializers import StudentInfoSerializer
>>> serializer = StudentInfoSerializer(student)
>>> serializer.data

result ：

Be careful ： If the associated object data is not only one , It contains multiple data , If you want to serialize ClassInfo data , Every ClassInfo Object associated StudentInfo The object may have more than one , At this time, the above methods can still be used to specify the associated field type , Only when declaring associated fields , Add one more many=True Parameters can be .

class ClassInfoSerializer(serializers.Serializer):
    """ Class data serializer """
    id = serializers.IntegerField(label='ID', read_only=True)
    number = serializers.IntegerField(label=' Class number ')
    grade = serializers.CharField(label=' grade ', max_length=3)
    studentinfo_set = serializers.PrimaryKeyRelatedField(read_only=True, many=True)  #  add to 

Use ：

>>> from demo.models import ClassInfo
>>> from demo.serializers import ClassInfoSerializer
>>> class_data = ClassInfo.objects.get(id=1)
>>> serializer = ClassInfoSerializer(class_data)

result ：

Next chapter ：DRF Learning notes ( Two ）: Data deserialization