I have the following models.
models.py
class Language(models.Model):
name = models.CharField(max_length=255, unique=True)
class Subject(models.Model):
name = models.CharField(max_length=255, unique=True)
class Term(models.Model):
subject = models.ForeignKey(Subject, on_delete=models.CASCADE)
language = models.ForeignKey(Language, on_delete=models.CASCADE)
name = models.CharField(max_length=255)
definition = models.TextField()
image = models.ImageField(default='', blank=True)
I want to write a Serializer that will return a list of subjects. Each subject has a term field, which contains None or a single object, depending on the condition.
serializers.py
class TermSerializer(serializers.ModelSerializer):
language = serializers.CharField(source='language.name')
def to_representation(self, data):
data = data.get(language=self.context['language'])
return super(TermSerializer, self).to_representation(data)
class Meta:
model = Term
fields = ('id', 'language', 'name', 'definition', 'image')
class FilteredSubjectSerializer(serializers.ListSerializer):
def to_representation(self, data):
if self.context['condition']:
terms = Term.objects.filter(language=self.context['language'])
data = data.filter(term__in=terms)
return super(FilteredSubjectSerializer, self).to_representation(data)
class SubjectSerializer(serializers.ModelSerializer):
term = serializers.SerializerMethodField()
def get_term(self, term):
if self.context['condition']:
return TermSerializer(many=False, source='term_set').data
return None
class Meta:
model = Term
list_serializer_class = FilteredSubjectSerializer
fields = ('id', 'name', 'definition', 'image', 'term')
The problem is that when condition == True, the ViewSet returns incorrect data. All fields inside term have a default value.
It works fine if I write SubjectSerializer like this:
class SubjectSerializer(serializers.ModelSerializer):
term = serializers.TermSerializer(many=False, source='term_set')
class Meta:
model = Term
list_serializer_class = FilteredSubjectSerializer
fields = ('id', 'name', 'definition', 'image', 'term')
But the case when condition == False doesn't work.
Try passing the serializer the instance and the context.
Like this:
def get_term(self, instance):
if self.context['condition']:
return TermSerializer(many=False, source='term_set', instance=instance, context=self.context).data
return None
Related
I have nested serializer (AmountSerializer). I need a field meal_name in one ViewSet. But when this field is nested, I don't need it to be seen in endpoint(in MealSerializer). How to exclude field from nested serializer when is it actually nested?
models.py:
class MealType(models.Model):
name = models.TextField()
def __str__(self):
return self.name
class Ingredient(models.Model):
name = models.TextField()
def __str__(self):
return self.name
class Meal(models.Model):
name = models.TextField()
type = models.ForeignKey(MealType, on_delete=models.CASCADE, default=None)
recipe = models.TextField()
photo = models.ImageField(null=True, height_field=None, width_field=None, max_length=None,upload_to='media/')
ingredients = models.ManyToManyField(Ingredient)
def __str__(self):
return self.name
class IngredientAmount(models.Model):
ingredient_name = models.ForeignKey(Ingredient, on_delete=models.CASCADE, default=None)
amount = models.FloatField(default=None)
meal = models.ForeignKey(Meal, on_delete=models.CASCADE, default=None, related_name='meal_id')
class Meta:
ordering = ['meal']
def __str__(self):
return self.ingredient_name
serializers.py:
class AmountSerializer(serializers.ModelSerializer):
ingredient_name= serializers.ReadOnlyField(source='ingredient_name.name')
-->#meal_name = serializers.ReadOnlyField(source='meal.name')
#I CAN'T use ReadOnlyField( #with write_only=True)
#i trired use PrimaryKeyRelatedField
# butgot AssertionError: Relational field must provide a `queryset` argument, override `get_queryset`, or set read_only=`True`.
class Meta:
model = IngredientAmount
fields = ('ingredient_name','amount','meal_name')
class MealSerializer(serializers.ModelSerializer):
type_name= serializers.ReadOnlyField(source='type.name')
ingredients = serializers.SlugRelatedField(read_only=True, slug_field='name', many=True)
amount = AmountSerializer(read_only=True, many=True,source='meal_id')
class Meta:
model = Meal
fields = ('id', 'name', 'type_name', 'recipe', 'photo', 'ingredients','amount')
I'd rather use a trick to exclude some of the fields that are not needed in certain situations. You can inherit your serializer from ExcludeFieldsModelSerializer, and exclude any fields that you want so that the serializer will not serialize that field.
class ExcludeFieldsModelSerializer(serializers.ModelSerializer):
"""
A ModelSerializer that takes an additional `exclude_fields` argument that
controls which fields should be excluded from the serializer.
Plagiarised from https://www.django-rest-framework.org/api-guide/serializers/#dynamically-modifying-fields
"""
def __init__(self, *args, **kwargs):
# Don't pass the 'exclude_fields' arg up to the superclass
exclude_fields = kwargs.pop('exclude_fields', None)
# Instantiate the superclass normally
super(ExcludeFieldsModelSerializer, self).__init__(*args, **kwargs)
if exclude_fields is not None:
# Drop any fields that are specified in the `exclude_fields` argument.
drop = set(exclude_fields)
for field_name in drop:
self.fields.pop(field_name)
class AmountSerializer(ExcludeFieldsModelSerializer):
ingredient_name= serializers.ReadOnlyField(source='ingredient_name.name')
meal_name = serializers.CharField(read_only=True, source='meal.name')
class Meta:
model = IngredientAmount
fields = ('ingredient_name','amount','meal_name')
class MealSerializer(serializers.ModelSerializer):
type_name= serializers.ReadOnlyField(source='type.name')
ingredients = serializers.SlugRelatedField(read_only=True, slug_field='name', many=True)
amount = AmountSerializer(read_only=True, many=True, source='meal_id', exclude_fields={'meal_name'})
class Meta:
model = Meal
fields = ('id', 'name', 'type_name', 'recipe', 'photo', 'ingredients','amount')
Want to use REST API to populate my tables but my field does not display on the API page.
Models (Series, Roster):
class Series(models.Model):
(...)
def __str__(self):
return self.title
class Roster(models.Model):
(...)
series = models.ManyToManyField(Series)
(...)
def __str__(self):
return self.name
Serializers:
class SeriesSerializer(serializers.ModelSerializer):
class Meta:
model = Series
fields = ('id', 'title', 'icon')
read_only_fields = ('slug',)
class RosterSerializer(serializers.ModelSerializer):
series = SeriesSerializer(many=True, read_only=True)
class Meta:
model = Roster
fields = ('id', 'name', 'number', 'primary_color', 'secondary_color', 'image', 'series')
Views:
class SeriesView(viewsets.ModelViewSet):
serializer_class = SeriesSerializer
queryset = Series.objects.all()
class RosterView(viewsets.ModelViewSet):
serializer_class = RosterSerializer
queryset = Roster.objects.all()
Unsure where I am mistepping here.
So it turns out that all I needed to do was remove
series = SeriesSerializer(many=True, read_only=True)
and adjust my series field to
series = models.ForeignKey(Series, on_delete=models.CASCADE, blank=True, null=True)
No idea why this ended up working though so an explanation would still be cool.
I am trying to update Contact model fields while creating the new fields of UpdateInfo model and add them to the existing model.
But I am getting this error
contacts.models.Contacts.DoesNotExist: Contacts matching query does not exist.
I know the contact object with the id 19 exists because I can see it when I try the get contacts API.
I am sending data like this.
My models:
class Contacts(models.Model):
full_name = models.CharField(max_length=100, blank=True)
.........
def __str__(self):
return self.full_name
class Meta:
verbose_name_plural = 'Potential Clients'
class UpdateInfo(models.Model):
contacts = models.ForeignKey(Contacts,on_delete=models.CASCADE, related_name='update_info')
updated_at = models.DateTimeField(auto_now=True)
modified_by = models.CharField(max_length=100, blank=True)
def __str__(self):
return f"Last modified by {self.modified_by} at {self.updated_at}"
My views:
class EditContactView(RetrieveUpdateDestroyAPIView):
permission_classes = [IsAuthenticated]
queryset = Contacts.objects.all()
serializer_class = ContactsUpdateSeializer
My serializers:
class UpdateInfoSerializer(serializers.ModelSerializer):
contacts= serializers.PrimaryKeyRelatedField(read_only=True)
class Meta:
model = UpdateInfo
fields = ['id','contacts','updated_at','modified_by']
class ContactsUpdateSeializer(serializers.ModelSerializer):
update_info = UpdateInfoSerializer(many=True)
id = serializers.PrimaryKeyRelatedField(read_only=True)
class Meta:
model = Contacts
fields = ['id', 'full_name', 'lead_source', 'email', 'phone', 'contact_owner',
'contact_status', 'company_name', 'job_position', 'tasks',
'notes', 'email_list', 'created_by', 'created_at', 'update_info']
def update(self, instance, validated_data):
update_data = validated_data.pop('update_info')
id = validated_data.get('id')
contacts = Contacts.objects.get(id=id)
#contacts.save()
#contact_only_update_logic
instance.full_name = validated_data.get('full_name')
instance.lead_source = validated_data.get('lead_source')
instance.email = validated_data.get('email')
instance.phone = validated_data.get('phone')
instance.contact_owner = validated_data.get('contact_owner')
instance.contact_status = validated_data.get('contact_status')
instance.company_name = validated_data.get('company_name')
instance.job_position = validated_data.get('job_position')
instance.tasks = validated_data.get('tasks')
instance.notes = validated_data.get('notes')
instance.email_list = validated_data.get('email_list')
instance.save()
#add_update_info_logic
for update_data in update_data:
abc = UpdateInfo.objects.create(contacts=contacts,**update_data)
instance.update_info.add(abc)
instance.save()
return instance
You have to change your serializer
class ContactsUpdateSeializer(serializers.ModelSerializer):
update_info = UpdateInfoSerializer(many=True)
class Meta:
model = Contacts
fields = ['id', 'full_name', 'lead_source', 'email', 'phone', 'contact_owner',
'contact_status', 'company_name', 'job_position', 'tasks',
'notes', 'email_list', 'created_by', 'created_at', 'update_info']
def update(self, instance, validated_data):
update_data = validated_data.pop('update_info')
instance = super(ContactsUpdateSeializer, self).update(instance, validated_data)
for update_datum in update_data:
abc = UpdateInfo.objects.create(contacts=instance,**update_datum)
return instance
PrimaryKeyRelatedField is used for foreign key purpose and there we have to define queryset also.
Don't need to add the updateinfo in contact, it is already done throgh django.
Moreover, it would be better if you use bulk_create instead of running save each time if you there is no signals exists for that.
You can do it as:-
UpdateInfo.objects.bulk_create([UpdateInfo(contacts=instance,**update_datum) for update_datum in update_data])
Django errors with django-import-export libraries.
I want to import data from excel to db via django admin. I use for it django-import-export, but i got Field 'id' expected a number but got 'HPI'.
Excel file contains
I found answer, that I have to add exclude = ('id',), but it didn't help. Also i did migrations, it didn't help too.
How to fix it and have ability to import 6 columns data from excel to db via django admin?
models.py
from django_mysql.models import JSONField, Model
from django.db import models
class Category(Model):
title = models.CharField(max_length=100)
class Meta:
ordering = ('-id',)
verbose_name = 'Category'
verbose_name_plural = 'Categories'
def __str__(self):
return self.title
class Tag(Model):
title = models.CharField(max_length=100)
class Meta:
ordering = ('-id',)
def __str__(self):
return self.title
class Type(Model):
title = models.CharField(max_length=100)
class Meta:
ordering = ('-id',)
verbose_name = 'Type'
verbose_name_plural = 'Types'
def __str__(self):
return self.title
class Macro(Model):
type = models.ForeignKey(
Type,
max_length=100,
null=True,
blank=True,
on_delete=models.SET_NULL)
tags = models.ManyToManyField(Tag, blank=True)
category = models.ForeignKey(
Category, null=True, blank=True, on_delete=models.SET_NULL)
abbreviation = models.CharField(max_length=100, unique=True)
title = models.CharField(max_length=100, verbose_name='Title')
content = models.TextField(max_length=1000, null=True, blank=True)
class Meta:
ordering = ('-id',)
def __str__(self):
return self.title
admin.py
from django.contrib import admin
from import_export import resources
from import_export.admin import ImportExportModelAdmin
from .models import Category, Tag, Type, Macro
class MacroResource(resources.ModelResource):
class Meta:
model = Macro
skip_unchanged = True
report_skipped = True
exclude = ('id', )
export_order = ('type', 'tags', 'category', 'abbreviation', 'title', 'content')
#admin.register(Macro)
class MacroAdmin(ImportExportModelAdmin):
resource_class = MacroResource
list_display = ('id', 'type', 'tags_list', 'category', 'abbreviation', 'title', 'content')
search_fields = ('title', 'category__title', 'type__title', 'abbreviation', 'content', )
def tags_list(self, obj):
tags = [t for t in obj.tags.all()]
return ' '.join(str(tags)) if tags else '-'
#admin.register(Category)
class CategoryAdmin(admin.ModelAdmin):
list_display = ('id', 'title')
#admin.register(Tag)
class TagAdmin(admin.ModelAdmin):
list_display = ('id', 'title')
def __str__(self):
return self.title
#admin.register(Type)
class TypeAdmin(admin.ModelAdmin):
list_display = ('id', 'title')
The problem was with ForeignKey and ManyToMany fields of a database model. So django-import-export library need to get widgets for this fields.
More about it here: https://django-import-export.readthedocs.io/en/latest/api_widgets.html#import_export.widgets.ForeignKeyWidget
Solution:
admin.py
class MacroResource(resources.ModelResource):
type = fields.Field(
column_name='type',
attribute='type',
widget=ForeignKeyWidget(Type, 'title'))
category = fields.Field(
column_name='category',
attribute='category',
widget=ForeignKeyWidget(Category, 'title'))
tags = fields.Field(
column_name='tags',
attribute='tags',
widget=ManyToManyWidget(Tag, field='title'))
class Meta:
model = Macro
skip_unchanged = True
report_skipped = True
exclude = ('id', )
import_id_fields = ('title',)
fields = ('type', 'tags', 'category', 'abbreviation', 'title', 'content')
instead of
class MacroResource(resources.ModelResource):
class Meta:
model = Macro
skip_unchanged = True
report_skipped = True
exclude = ('id', )
export_order = ('type', 'tags', 'category', 'abbreviation', 'title', 'content')
Django-import-export expects the first column to be id.
If these are new objects, simply leave the id column blank. Otherwise, put the database id of the object in that field.
If you're not able to modify the file, or don't want to, and you will always be adding new rows to the database (not modifying existing ones), you can create an id field dynamically in your resource class by overriding the method before_import and forcing get_instance to always return False.
class MacroResource(resources.ModelResource):
def before_import(self, dataset, using_transactions, dry_run, **kwargs):
dataset.insert_col(0, col=["",]*dataset.height, header="id")
def get_instance(self, instance_loader, row):
return False
class Meta:
model = Macro
skip_unchanged = True
report_skipped = True
export_order = ('type', 'tags', 'category', 'abbreviation', 'title', 'content')
The attributes where you are using a foreign key in the model,
you need to specify the id of the parent model and not the value in the xlsx/csv file.
These are my models and serializers. I want a representation of Question Model along with a list of people the question was asked to.
I am trying this:
#api_view(['GET', 'PATCH'])
def questions_by_id(request,user,pk):
question = Question.objects.get(pk=pk)
if request.method == 'GET':
serializer = QuestionSerializer(question)
return Response(serializer.data)
But I get an empty dictionary ({}). However when I remove the asked field from QuestionSerializer I get a complete representation of Question along with Places serialized nicely. What am I missing ?
class AskedToSerializer(serializers.ModelSerializer):
class Meta:
model = AskedTo
fields = ('to_user', 'answered')
class QuestionSerializer(serializers.ModelSerializer):
class Meta:
model = Question
places = PlaceSerializer(many=True, required=False)
asked = AskedToSerializer(source='askedto_set', many=True)
fields = ('id', 'created_on', 'title', 'places', 'answered','asked')
extra_kwargs = {'created_by': {'read_only': True}}
class Question(BaseModel):
title = models.CharField(max_length=200, null=False)
places = models.ManyToManyField(Place, blank=True)
answered = models.BooleanField(default=False)
class AskedTo(BaseModel):
ques = models.ForeignKey(Question, on_delete=models.CASCADE)
to_user = models.ForeignKey(settings.AUTH_USER_MODEL)
replied = models.BooleanField(default=False)
class Place(models.Model):
g_place_id = models.CharField(max_length=20,primary_key=True)
json = models.TextField(null=True)
name = models.CharField(max_length=40)
I figured it out. There were two errors.
Changed this:
class AskedToSerializer(serializers.ModelSerializer):
class Meta:
model = AskedTo
fields = ('to_user', 'answered')
to this (notice the change in fields, fields on model and serializer didn't match)
class AskedToSerializer(serializers.ModelSerializer):
class Meta:
model = AskedTo
fields = ('to_user', 'replied')
Secondly, I needed to define any extra fields outside class Meta
class QuestionSerializer(serializers.ModelSerializer):
places = PlaceSerializer(many=True, required=False)
asked = AskedToSerializer(source='askedto_set', many=True)
class Meta:
model = Question
fields = ('id', 'created_on', 'title', 'places', 'answered','asked')
extra_kwargs = {'created_by': {'read_only': True}}
Notice the change in definition of places and asked.
In my case, I have this models.py:
class Section(models.Model):
title = models.CharField(max_length=500)
description = models.TextField(blank=True)
user = models.ForeignKey(Profile, related_name="sections", on_delete=models.CASCADE)
class Feed(models.Model):
title = models.CharField(max_length=500)
link_rss = models.URLField(max_length=500)
link_web = models.URLField(max_length=500)
description = models.TextField(blank=True)
language = models.CharField(max_length=50, blank=True)
logo = models.URLField(blank=True)
sections = models.ManyToManyField(Section, related_name="feeds")
And I completed the serializers.py this:
class FeedSerializer(serializers.ModelSerializer):
sections = serializers.PrimaryKeyRelatedField(many=True, read_only=True)
class Meta:
model = Feed
fields = '__all__'
class SectionSerializer(serializers.ModelSerializer):
feeds = FeedSerializer(many=True, read_only=True)
class Meta:
model = Section
exclude = ('user',)