I'm a big fan of Django-parler, but I've run into a problem when storing a translated model in two different databases.
My model is:
class InstrumentFamily(TranslatableModel):
primary_key = True
translations = TranslatedFields(
label=CharNullField(_('Label'), max_length=100, unique=False, null=True,)
I have 2 database aliases 'default' and 'test' and my database router directs my model to 'test'.
I insert models in both databases by doing this:
fam = InstrumentFamily(code=TEST_CODE)
with switch_language(fam, 'en'):
fam.label = "test_family_test EN"
with switch_language(fam, 'fr'):
fam.label = "test_family_test FR"
fam.save()
which stores the object and its translations in database 'test', or by doing this:
fam = InstrumentFamily(code="TEST_FAM")
with switch_language(fam, 'en'):
fam.label = "test_family_default_EN"
with switch_language(fam, 'fr'):
fam.label = "test_family_default_FR"
fam.save(using='default')
which saves the object and its translations to database 'default'. So far, so good.
But when accessing the object previously saved in 'default' by doing this (after properly clearing all caches to force a database read):
fam = InstrumentFamily.objects.using('default').get(code=TEST_CODE)
print(f" label: {fam.label}")
django-parler properly retrieves the object from database 'default', but looks for the translation from database 'test' ! (SQL trace below, see the very end of each line):
SELECT "orchestra_instrumentfamily"."id", "orchestra_instrumentfamily"."code" FROM "orchestra_instrumentfamily" WHERE "orchestra_instrumentfamily"."code" = 'TEST_FAM' LIMIT 21; args=('TEST_FAM',); alias=default
SELECT "orchestra_instrumentfamily_translation"."id", "orchestra_instrumentfamily_translation"."language_code", "orchestra_instrumentfamily_translation"."label", "orchestra_instrumentfamily_translation"."master_id" FROM "orchestra_instrumentfamily_translation" WHERE ("orchestra_instrumentfamily_translation"."master_id" = 34 AND "orchestra_instrumentfamily_translation"."language_code" = 'en') LIMIT 21; args=(34, 'en'); alias=test
I'm obviously missing something big... What am I supposed to do to have the 'using("default")' information propagated to the second query? I couldn't find anything in the documentation about storing TranslatableModels in more than one database. Am I trying to achieve something parler does not support?
Thanks in advance for enlightening me!
This looks like a bug in django-parler. It doesn't pass the using information to its internal queries that retrieve translation model data. You can file a bit in the GitHub repository so this can be addressed.
A workaround would be to implement a database-router that enforces using a particular database for this model.
Related
I am new to Django, and I am looking for the best approach to the following problem.
I have an application that is producing two reports. One is a JSON blob so I store it in psql with data model that uses JSONField.
The second report is a .html file.
The .html file will be generated multiple times a day so the first thing that came to mind was storing it in the db.
I need to be able to pull the report as well so it can be displayed to the user in the UI.
I created a test data model using TextField:
class TestResultsHTML(models.Model):
name = models.CharField(max_length=200)
report = models.TextField()
It makes it into the Db no problem, however when I attempt to retrieve it I can't seem to get the actual report:
In [3]: html_results = TestResultsHTML.objects.get(id=4)
In [4]: html_results.name
Out[4]: 'b0f5c336-867a-44a3-a5ef-6297bf6042cf'
In [5]: html_results.report
Out[5]: "<_io.TextIOWrapper name='report.html' mode='r' encoding='UTF-8'>"
I was expected that .report would return the actual contents of the file. The file itself is 1800+ lines.
Is this a good approach or is this not the intended use of TextField?
A TextField doesn't store the file, Django has a FileField for this (see here). This saves the file to a certain location/folder and the object saved in the DB essentially stores that location which you can then access later. Something like this:
class TestResultsHTML(models.Model):
name = models.CharField(max_length=200)
file_loc = models.FileField(upload_to=upload_location)
Then open the file at a later date with something like this:
with open(html_results.file_loc, 'w'):
This is the model that has to be searched:
class BlockQuote(models.Model):
debate = models.ForeignKey(Debate, related_name='quotes')
speaker = models.ForeignKey(Speaker, related_name='quotes')
text = models.TextField()
I have around a thousand instances on the database on my laptop (with around 50000 on the production server)
I am creating a 'manage.py' function that will search through the database and returns all 'BlockQuote' objects whose textfield contains the keyword.
I am doing this with the Django's (1.11) Postgres search options in order to use the 'rank' attribute, which sounds like something that would come in handy. I used the official Django fulltext-search documentation for the code below
Yet when I run this code, it matches with all objects, regardless if BlockQuote.text actually contains the queryfield.
def handle(self, *args, **options):
vector = SearchVector('text')
query = options['query'][0]
Search_Instance = Search_Instance.objects.create(query=query)
set = BlockQuote.objects.annotate(rank=SearchRank(vector, query)).order_by('-rank')
for result in set:
match = QueryMatch.objects.create(quote=result, query=Search_Instance)
match.save()
Does anyone have an idea of what I am doing wrong?
I don't see you actually filtering ever.
BlockQuote.objects.annotate(...).filter(rank__gte=0.5)
I'm working with a database in Django. I'm familiar with the Django database API but am wondering how to interact with the data base inside views.py. Here's the relevant model:
class SlotFilling(models.Model):
originator = models.CharField(max_length=20)
empty_slot = models.BooleanField(default=False)
I'm trying to write an If statment in my program to check if empty_slot is True for a given originator. I'm thinking I might be able to use filter() to accomplish this. Any experience with the most efficient way to implement this?
If you are looking to query for originator all empty slots you can do something as following
SlotFilling.objects.filter(empty_slot=True, originator='someoriginator')
#comment code
Assuming originator is unique
originator_slot = SlotFlling.objects.get(originator='originator')
slot_value = originator_slot.empty_slot
You can use filter instead if originator is not unique, which would list you back all rows for particular originator
originator_slots = SlotFlling.objects.filter(originator='originator')
for originator_slot in originator_slots:
print originator_slot.empty_slot
Also please check out retrieving objects in DB API documentation as saying that you are familiar with it would be big overstatement :)
Good afternoon,
I have my django server running with a REST api on top to serve my mobile devices. Now, at some point, the mobile device will communicate with Django.
Let's say the device is asking Django to add an object in the database, and within that object, I need to set a FK like this:
objectA = ObjectA.objects.create(title=title,
category_id = c_id, order = order, equipment_id = e_id,
info_maintenance = info_m, info_security = info_s,
info_general = info_g, alphabetical_notation = alphabetical_notation,
allow_comments = allow_comments,
added_by_id = user_id,
last_modified_by_id = user_id)
If the e_id and c_id is received from my mobile devices, should I check before calling this creation if they actually still exists in the DB? That is two extra queries... but if they can avoid any problems, I don't mind!
Thanks a lot!
It think that Django creates constraint on Foreign Key by default ( might depend on database though ). This means that if your foreign keys point to something that does not exist, then saving will fail ( resulting in Exception on Python side ).
You can reduce it to a single query (it should be a single query at least, warning I haven't tested the code):
if MyObject.objects.filter(id__in=[e_id, c_id]).distinct().count() == 2:
# create the object
ObjectA.objects.create(...)
else:
# objects corresponding e_id and c_id do not exist, do NOT create ObjectA
You should always validate any information that's coming from a user or that can be altered by a determined user. It wouldn't be difficult for someone to sniff the traffic and start constructing their own REST requests to your server. Always clean and validate external data that's being added to the system.
I have a database of exhibition listings related by foreign key to a database of venues where they take place. Django templates access the venue information in the query results through listing.venue.name, listing.venue.url, and so on.
However, some exhibitions take place in temporary venues, and that information is stored in the same database, in what would be listing.temp_venue_url and such. Because it seems wasteful and sad to put conditionals all over the templates, I want to move the info for temporary venues to where the templates are expecting info for regular venues. This didn't work:
def transfer_temp_values(listings):
for listing in listings:
if listing.temp_venue:
listing.venue = Venue
listing.venue.name = listing.temp_venue
listing.venue.url = listing.temp_venue_url
listing.venue.state = listing.temp_venue_state
listing.venue.location = listing.temp_venue_location
The error surprised me:
ValueError at /[...]/
Cannot assign "<class 'myproject.gsa.models.Venue'>": "Exhibition.venue" must be a "Venue" instance.
I rather thought it was. How do I go about accomplishing this?
The error message is because you have assigned the class Venue to the listing, rather than an instance of it. You need to call the class to get an instance:
listing.venue = Venue()