0006_content_streamfield_data.py

# Generated by Django 2.2.1 on 2019-05-03 13:18

import json
from uuid import uuid4
from copy import deepcopy
from django.core.serializers.json import DjangoJSONEncoder
from django.db import migrations
from wagtail.core.blocks import StreamValue
from home.models import ExamplePage


def copy_page_data_to_content_streamfield(apps, schema_editor):
    """With the given page, copy the page data to the content stream_data"""
    for page in ExamplePage.objects.all():
        page_data = json.loads(page.to_json())
        content_data = page_data_to_content_streamfield_data(page_data)
        if content_data != page.content.stream_data:
            page.content.stream_data = content_data
            page.save()
        for revision in page.revisions.all():
            revision_data = json.loads(revision.content_json)
            content_data = page_data_to_content_streamfield_data(revision_data)
            if content_data != revision_data.get('content'):
                # StreamField data is stored in revision.content_json in a string field
                revision_data['content'] = json.dumps(content_data)
                revision.content_json = json.dumps(
                    revision_data, cls=DjangoJSONEncoder)
                revision.save()


def prevent_reverse_migration(apps, schema_editor):
    return
    raise NotImplementedError(
        "This migration cannot be reversed without" +
        " inordinate expenditure of time. You can" +
        " `--fake` it if you know what you're doing," +
        " and are a migration ninja.", )


class Migration(migrations.Migration):

    dependencies = [
        ('home', '0005_add_content_streamfield'),
    ]

    operations = [
        migrations.RunPython(
            copy_page_data_to_content_streamfield,
            prevent_reverse_migration,
        )
    ]


def page_data_to_content_streamfield_data(page_data):
    """With the given page field data, build and return content stream_data:
    * Copy existing page data into new stream_data.
    * Handle either the main page data or any revision data.
    * page_data is unchanged! (treated as immutable).
    """
    content_data = [
        {
            'type': 'image',
            'value': page_data['image']
        },
        {
            'type': 'text',
            'value': page_data['body']
        },
        {
            'type':
            'docs',
            'value': [{key: block_data[key]
                       for key in ['type', 'value']}
                      for block_data in json.loads(page_data['docs'])]
        },
    ]
    return content_data