django-elasticsearch-dsl not syncing for Nested Filed

Question

I've created a django-elasticsearch document(PostDocument) against some models(post, comment, ReactForComment). Everything is working fine. However, after updating ReactForComment model the PostDocument is not getting update. My assumption is, I need to work on def get_instances_from_related(self, related_instance): or prepare_field but can't figure out the way.

models.py

class Post(models.Model):
    STATUS_CHOICES = (
        ('draft', 'Draft'),
        ('published', 'Published'),
    )
    title = models.CharField(max_length=250)
    slug = models.SlugField(max_length=250, unique_for_date='publish')
    author = models.ForeignKey(User, on_delete=models.CASCADE, related_name='blog_posts')
    body = models.TextField()
    publish = models.DateTimeField(default=timezone.now)
    created = models.DateTimeField(auto_now_add=True)
    updated = models.DateTimeField(auto_now=True)
    status = models.CharField(max_length=10, choices=STATUS_CHOICES, default='draft')
    tags = TaggableManager()

    def __str__(self):
        return self.title


class Comment(models.Model):
    post = models.ForeignKey(Post, on_delete=models.CASCADE, related_name='post_comments')
    name = models.CharField(max_length=80)
    body = models.TextField()
    email = models.EmailField()
    created = models.DateTimeField(auto_now_add=True)
    updated = models.DateTimeField(auto_now=True)
    active = models.BooleanField(default=True)

    class Meta:
        ordering = ['created']

    def __str__(self):
        return f'Comment by {self.name} on {self.post}'


class ReactForComment(models.Model):
    comment = models.ManyToManyField(Comment, on_delete=models.CASCADE, related_name='react_comments')
    like = models.IntegerField(null=True, blank=True)
    happy = models.IntegerField(null=True, blank=True)
    sad = models.IntegerField(null=True, blank=True)
    neutral = models.IntegerField(null=True, blank=True)

    def __str__(self):
        return f'React on {self.comment}'

Document.py

@registry.register_document
class PostDocument(Document):
    post_comments = fields.NestedField(properties={
        'id': fields.IntegerField(),
        'react_comments': fields.NestedField(properties={
            'id': fields.IntegerField(),
            'like': fields.IntegerField(),
            'happy': fields.IntegerField(),
            'sad': fields.IntegerField(),
            'neutral': fields.IntegerField()
        })
    })

    class Index:
        name = 'post'
        settings = {'number_of_shards': 1,
                    'number_of_replicas': 1}

    class Django:
        model = Post

        fields = [
            'id',
            'title',
            'author',
            'body',
        ]
        related_models = [Comment, ReactForComment]

    def get_instances_from_related(self, related_instance):
        if isinstance(related_instance, Comment):
            return related_instance.post

user_4471795 · Answer

I believe you need to fix your get_instances_from_related method. It is returning the object when the comment object is passed, but it does not handle the ReactForComment model in get_instances_from_related method.

def get_instances_from_related(self, related_instance):
    if isinstance(related_instance, Comment):
        return related_instance.post
    if isinstance(related_instance, ReactForComment):
        # Write some code to return the Post object

PS: I believe the comment field in ReactForComment should be ForeignKey instead of ManyToMany.

user_11040735 · Answer

Define a queryset method so that it will fetch related comments on post retrieval.

def get_queryset(self):
    return super().get_queryset().prefetch_related('post_comments')

In get_instance_from_related method

def get_instance_from_related(self, related_instance):
    if isinstance(related_instance, Comment):
            return related_instance.post
    elif isinstance(related_instance, ReactForComment):
            # if it is a ReactForComment then return the post object from that comment in which this react exists
            return related_instance.comment.post

Note: ReactForComment should be foreign key instead of many-to-many as mentioned by @safwan

django-elasticsearch-dsl not syncing for Nested Filed

2 Answers