django-mysql-compressed-fields
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A large text field, stored compressed in the database, for Django and MySQL.
This package provides CompressedTextField, a MySQL-specific Django model field similar to TextField or CharField that stores its value in compressed form via zlib.
In particular you can replace a TextField or CharField like:
from django.db import models
class ProjectTextFile(models.Model):
content = models.TextField(blank=True)
with:
from django.db import models
from mysql_compressed_fields import CompressedTextField
class ProjectTextFile(models.Model):
content = CompressedTextField(blank=True)
such that the text value of the field is actually compressed in the database.
String-based lookups are supported:
html_files = ProjectTextFile.objects.filter(content__contains='<html')
html_files = ProjectTextFile.objects.filter(content__startswith='<!DOCTYPE')
html_files = ProjectTextFile.objects.filter(content__endswith='</html>')
empty_html_files = ProjectTextFile.objects.filter(content__in=['', '<html></html>'])
Advanced manipulations with MySQL's COMPRESS(), UNCOMPRESS(), and UNCOMPRESSED_LENGTH() functions are also supported:
from django.db.models import F
from mysql_compressed_fields import UncompressedLength
files = ProjectTextFile.objects.only('id').annotate(
content_length=UncompressedLength(F('content'))
)
To migrate an existing TextField or CharField to be a CompressedTextField:
pip3 install django-mysql-compressed-fieldsfrom django.db import models
class ProjectTextFile(models.Model):
content = models.TextField(blank=True)
*_compressed sibling field that will be used to hold the compressed
version of the original field. Mark it as default=''. Include an explicit
db_column=... value:from django.db import models
from mysql_compressed_fields import CompressedTextField
class ProjectTextFile(models.Model):
content = models.TextField(blank=True)
content_compressed = CompressedTextField(
blank=True,
default='', # needed by Django when adding a field
db_column='content_compressed', # pin column name
)
python3 manage.py makemigrationspython3 manage.py makemigrations --empty __APP_NAME__from django.db import migrations
class Migration(migrations.Migration):
dependencies = [
('ide', '0002_projecttextfile_content_compressed'),
]
operations = [
]
operations field to use a RunPython step to populate
the compressed field from the uncompressed field:from django.db import migrations
from django.db.models import F
from mysql_compressed_fields import Compress
def _populate_content_compressed(apps, schema_editor):
ProjectTextFile = apps.get_model('ide', 'ProjectTextFile')
# NOTE: Assumes "content" field is already UTF-8 encoded,
# because CompressedTextField assumes UTF-8 encoding.
ProjectTextFile.objects.update(content_compressed=Compress(F('content')))
class Migration(migrations.Migration):
dependencies = [
('ide', '0002_projecttextfile_content_compressed'),
]
operations = [
migrations.RunPython(
code=_populate_content_compressed,
reverse_code=migrations.RunPython.noop,
atomic=False,
)
]
from django.db import models
from mysql_compressed_fields import CompressedTextField
class ProjectTextFile(models.Model):
content_compressed = CompressedTextField(
blank=True,
default='', # needed by Django when adding a field
db_column='content_compressed', # pin column name
)
python3 manage.py makemigrations*_compressed suffix
so that it now has the name of the original uncompressed field:from django.db import models
from mysql_compressed_fields import CompressedTextField
class ProjectTextFile(models.Model):
content = CompressedTextField(
blank=True,
default='', # needed by Django when adding a field
db_column='content_compressed', # pin column name
)
python3 manage.py makemigrationsy (for yes).This project is brought to you by TechSmart, which seeks to inspire the next generation of K-12 teachers and students to learn coding and create amazing things with computers. We use Django heavily.
All classes and functions below should be imported directly from
mysql_compressed_fields. For example:
from mysql_compressed_fields import CompressedTextField
CompressedTextFieldclass CompressedTextField(encode_errors='strict', decode_errors='strict', **options)A large text field, stored compressed in the database.
Generally behaves like TextField. Stores values in the database using the same database column type as BinaryField. The value is compressed in the same format that MySQL's COMPRESS() function uses. Compression and decompression is performed by Django and not the database.
encode_errors controls how encoding errors are handled when saving the field. decode_errors controls how decoding errors are handled when loading the field. If 'strict' (the default), a UnicodeError exception is raised. Other possible values are 'ignore', 'replace', and any other name registered via codecs.register_error(). See Error Handlers for details.
If you specify a max_length attribute, it will be reflected in the
Textarea widget of the auto-generated form field. However it is not
enforced at the model or database level. The max_length applies to the
length of the uncompressed text rather than the compressed text.
String-based lookups can be used with this field type. Such lookups will transparently decompress the field on the database server.
html_files = ProjectTextFile.objects.filter(content__contains='<html')
html_files = ProjectTextFile.objects.filter(content__startswith='<!DOCTYPE')
html_files = ProjectTextFile.objects.filter(content__endswith='</html>')
empty_html_files = ProjectTextFile.objects.filter(content__in=['', '<html></html>'])
Note that F-expressions that reference this field type will always refer to the compressed value rather than the uncompressed value. So you may need to use the Compress() and Uncompress() database functions manually when working with F-expressions.
# Copy a TextField value (in utf8 collation) to a CompressedTextField
ProjectTextFile.objects.filter(...).update(content=Compress(F('name')))
# Copy a CompressedTextField value to a TextField (in utf8 collation)
ProjectTextFile.objects.filter(...).update(name=Uncompress(F('content')))
# Copy a CompressedTextField value to a CompressedTextField
ProjectTextFile.objects.filter(...).update(content=F('content'))
The default form widget for this field is a
django.contrib.admin.widgets.AdminTextareaWidget (a kind of TextInput).
CompressThe MySQL COMPRESS() function, usable in F() expressions.
UncompressThe MySQL UNCOMPRESS() function, usable in F() expressions.
UncompressedLengthThe MySQL UNCOMPRESSED_LENGTH() function, usable in F() expressions.
compressdef compress(uncompressed_bytes: bytes) -> bytes:
The MySQL COMPRESS() function.
uncompressdef uncompress(compressed_bytes: bytes) -> bytes:
The MySQL UNCOMPRESS() function.
uncompressed_lengthdef uncompressed_length(compressed_bytes: bytes) -> int:
The MySQL UNCOMPRESSED_LENGTH() function.
compressed_lengthdef compressed_length(
uncompressed_bytes: bytes,
*, chunk_size: int=64 * 1000,
stop_if_greater_than: Optional[int]=None) -> int:
Returns the length of COMPRESS(uncompressed_bytes).
If stop_if_greater_than is specified and a result greater than
stop_if_greater_than is returned then the compressed length is
no less than the returned result.
brew install mysql-client@8.0export PATH="/usr/local/opt/mysql-client@8.0/bin:$PATH"docker run --name ide_db_server -e MYSQL_DATABASE=ide_db -e MYSQL_ROOT_PASSWORD=root -p 127.0.0.1:8889:3306 -d mysql:8.0cd tests/test_data/mysitepoetry installpoetry run python3 manage.py testencode_errors and decode_errors options to CompressedTextField.FAQs
A large text field, stored compressed in the database, for Django and MySQL.
We found that django-mysql-compressed-fields demonstrated a healthy version release cadence and project activity because the last version was released less than a year ago. It has 1 open source maintainer collaborating on the project.
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