I am trying to extract records with my Django ORM Model:
users = User.objects.values( "first_name", "last_name" ).annotate( user_level=custom_levels( F("user_level" ) ) );
The model is represented by:
first_name
last_name
user_level: it may be [1] or [1,13] (it comes from saving a MultipleSelect throught forms.py)
Goal:
My goal is to process user_level in the query in order to transform those ids in text (I have a dict key:value with those ids). For that I was thinking of writing a function, custom_level, to process the pairing job.
I am using annotate() but I am not really sure of its correct use.
How would you process the pairing between ids and text in order to get a single text line?
Any clue?
Thank you
Don't see a reason why you should do it on ORM level. Why don't you just make it with model's property, which would transform this field value onto desired? Like this:
class User(AbstractUser):
# ...
#property
def user_level_description(self):
level_descriptions = {
1: "Level One",
2: "Level Two",
# ...
}
return ", ".join(level_descriptions[level] for level in self.user_level)
Related
I have an object model where Documents are long text files that can have Attachments and both sets of objects can also have spreadsheet-like Tables. Each table has a rectangular array with text. I want users to be able to search for a keyword across the table contents, but the results will be displayed by the main document (so instead of seeing each table that matches, you'll just see the document that has the most tables that match your query).
Below you can see a test query I'm trying to run that in an ideal world would convert all of the table contents (across all attachments) to one long string, that I can then pass to a SearchHighlight to make the headline. For some reason, the test query returns the tables as different objects, rather than concatenated to one long string.
I'm using a custom function that mimics the Postgres 13 StringAgg as I'm using Postgres 10.
Thanks in advance for your help, let me know if I need to provide more information to replicate this.
my models.py:
class Document(AbstractDocument):
tables = GenericRelation(Table)
class Attachment(AbstractDocument):
tables_new = GenericRelation(Table)
main_document = ForeignKey(Document, on_delete=CASCADE, related_name="attachments")
class Table(models.Model):
content_type = models.ForeignKey(ContentType, on_delete=models.CASCADE)
object_id = models.SlugField()
content_object = GenericForeignKey()
content = ArrayField(ArrayField(models.TextField(null=True)))
my query:
def myStringAgg(field: str):
return Func(
F(field),
Value(" "),
Value(""),
function="array_to_string",
output_field=models.TextField(),
)
s = Document.objects.all() \
.annotate(tt=myStringAgg("attachments__tables__content")) \
.values_list('tt', flat=True)
# what I get
>>> <DocumentSet ['table1', 'table2']>
# what I want
>>> <DocumentSet ['table1 table2']>
I'm using Django 3.2 and Postgres 10.
To clarify what my full scope is, this what the final query would look like:
qs = Document.objects.filter(
Q(tables__search_vector=query) |
Q(attachments__tables__search_vector=query)
)
.annotate(rank=rank)
.order_by("-rank")
.annotate(snippet=SearchHeadline(
myStringAgg("attachments__tables__content"),
query, max_fragments=5)
)
You can use the join function to create a string from a list:
s = Document.objects.all() \
.annotate(tt=myStringAgg("attachments__tables__content")) \
.values_list('tt', flat=True)
s = " ". join(list(s))
Bonjour, I have a question regarding django-filters. My problem is:
I have two classes defined in my models.py that are:
class Volcano(models.Model):
vd_id = models.AutoField("ID, Volcano Identifier (Index)",
primary_key=True)
[...]
class VolcanoInformation(models.Model):
# Primary key
vd_inf_id = models.AutoField("ID, volcano information identifier (index)",
primary_key=True)
# Other attributes
vd_inf_numcal = models.IntegerField("Number of calderas")
[...]
# Foreign key(s)
vd_id = models.ForeignKey(Volcano, null=True, related_name='vd_inf_vd_id',
on_delete=models.CASCADE)
The two of them are linked throught the vd_id attribute.
I want to develop a search tool that allows the user to search a volcano by its number of calderas (vd_inf_numcal).
I am using django-filters and for now here's my filters.py:
from .models import *
import django_filters
class VolcanoFilter(django_filters.FilterSet):
vd_name = django_filters.ModelChoiceFilter(
queryset=Volcano.objects.values_list('vd_name', flat=True),
widget=forms.Select, label='Volcano name',
to_field_name='vd_name',
)
vd_inf_numcal = django_filters.ModelChoiceFilter(
queryset=VolcanoInformation.objects.values_list('vd_inf_numcal', flat=True),
widget=forms.Select, label='Number of calderas',
)
class Meta:
model = Volcano
fields = ['vd_name', 'vd_inf_numcal']
My views.py is:
def search(request):
feature_list = Volcano.objects.all()
feature_filter = VolcanoFilter(request.GET, queryset = feature_list)
return render(request, 'app/search_list.html', {'filter' : feature_filter, 'feature_type': feature_type})
In my application, a dropdown list of the possible number of calderas appears but the search returns no result which is normal because there is no relation between VolcanoInformation.vd_inf_numcal, VolcanoInformation.vd_id and Volcano.vd_id.
It even says "Select a valid choice. That choice is not one of the available choices."
My question is how could I make this link using django_filters ?
I guess I should write some method within the class but I have absolutely no idea on how to do it.
If anyone had the answer, I would be more than thankful !
In general, you need to answer two questions:
What field are we querying against & what query/lookup expressions need to be generated.
What kinds of values should we be filtering with.
These answers are essentially the left hand and right hand side of your .filter() call.
In this case, you're filtering across the reverse side of the Volcano-Volcano Information relationship (vd_inf_vd_id), against the number of calderas (vd_inf_numcal) for a Volcano. Additionally, you want an exact match.
For the values, you'll need a set of choices containing integers.
AllValuesFilter will look at the DB column and generate the choices from the column values. However, the downside is that the choices will not include any missing values, which look weird when rendered. You could either adapt this field, or use a plain ChoiceFilter, generating the values yourself.
def num_calderas_choices():
# Get the maximum number of calderas
max_count = VolcanoInformation.objects.aggregate(result=Max('vd_inf_numcal'))['result']
# Generate a list of two-tuples for the select dropdown, from 0 to max_count
# e.g, [(0, 0), (1, 1), (2, 2), ...]
return zip(range(max_count), range(max_count))
class VolcanoFilter(django_filters.FilterSet):
name = ...
num_calderas = django_filters.ChoiceFilter(
# related field traversal (note the connecting '__')
field_name='vd_inf_vd_id__vd_inf_numcal',
label='Number of calderas',
choices=num_calderas_choices
)
class Meta:
model = Volcano
fields = ['name', 'num_calderas']
Note that I haven't tested the above code myself, but it should be close enough to get you started.
Thanks a lot ! That's exactly what I was looking for ! I didn't understand how the .filter() works.
What I did, for other attributes is to generate the choices but in a different way. For instance if I just wanted to display a list of the available locations I would use:
# Location attribute
loc = VolcanoInformation.objects.values_list('vd_inf_loc', flat=True)
vd_inf_loc = django_filters.ChoiceFilter(
field_name='vd_inf_vd_id__vd_inf_loc',
label='Geographic location',
choices=zip(loc, loc),
)
I am working with Odoo 10.
I have a one2many field with two columns in the hr.employee model. If the field "Bonus" (many2one field) is assigned to a particular date, it should not be saved or repeated once again on the same date.
How to achieve this?
Take a look at this below code, this is one possible solution, not the best.
from odoo import models, fields, api
from odoo.exceptions import ValidationError
class HrEmployee(models.Model):
_inherit = 'hr.employee'
prod_details_ids = fields.One2many(
string=u'Product details',
comodel_name='prod.details',
inverse_name='employee_id',
)
class ProdDetails(models.Model):
_name = 'prod.details'
employee_id = fields.Many2one(
string=u'Employee',
comodel_name='hr.employee',
)
date = fields.Date(
string=u'Date',
default=fields.Date.context_today,
)
bonus_id = fields.Many2one(
string=u'Bonus',
comodel_name='res.partner', # just an example
)
And then you need to add the constrains:
Solution 1
_sql_constraints = [
('bonus_unique', 'unique(employee_id, date, bonus_id)',
_('Date + Bonus cannot be repeated in one employee!')),
]
Solution 2
#api.one
#api.constrains('date', 'bonus_id')
def _check_unique_date(self):
# you have more freedom here if you want to check more things
rest = self.employee_id.prod_details_ids - self
for record in rest:
if record.date == self.date and record.bonus_id.id == self.bonus_id.id:
raise ValidationError("Date + Bonus already exists and violates unique field constraint")
Note: If you have date already in your database make sure that the constrains can be added with this data, because if not the constraint cannot be added to the database. This happens with the _sql_constraints at least
Use constrains to stop creating another record with the same name, so duplication of records doesnot occur.
you can use constraints and the search_count() method to check if there is a record. like below
#api.constraints('date')
def validate_date(self):
result = self.search_count([your_domain])
if result:
raise ValidationError(_('Your Text'))
I would like to be able to check if a related object has already been fetched by using either select_related or prefetch_related, so that I can serialize the data accordingly. Here is an example:
class Address(models.Model):
street = models.CharField(max_length=100)
zip = models.CharField(max_length=10)
class Person(models.Model):
name = models.CharField(max_length=20)
address = models.ForeignKey(Address)
def serialize_address(address):
return {
"id": address.id,
"street": address.street,
"zip": address.zip
}
def serialize_person(person):
result = {
"id": person.id,
"name": person.name
}
if is_fetched(person.address):
result["address"] = serialize_address(person.address)
else:
result["address"] = None
######
person_a = Person.objects.select_related("address").get(id=1)
person_b = Person.objects.get(id=2)
serialize_person(person_a) #should be object with id, name and address
serialize_person(person_b) #should be object with only id and name
In this example, the function is_fetched is what I am looking for. I would like to determine if the person object already has a resolves address and only if it has, it should be serialized as well. But if it doesn't, no further database query should be executed.
So is there a way to achieve this in Django?
Since Django 2.0 you can easily check for all fetched relation by:
obj._state.fields_cache
ModelStateFieldsCacheDescriptor is responsible for storing your cached relations.
>>> Person.objects.first()._state.fields_cache
{}
>>> Person.objects.select_related('address').first()._state.fields_cache
{'address': <Address: Your Address>}
If the address relation has been fetched, then the Person object will have a populated attribute called _address_cache; you can check this.
def is_fetched(obj, relation_name):
cache_name = '_{}_cache'.format(relation_name)
return getattr(obj, cache_name, False)
Note you'd need to call this with the object and the name of the relation:
is_fetched(person, 'address')
since doing person.address would trigger the fetch immediately.
Edit reverse or many-to-many relations can only be fetched by prefetch_related; that populates a single attribute, _prefetched_objects_cache, which is a dict of lists where the key is the name of the related model. Eg if you do:
addresses = Address.objects.prefetch_related('person_set')
then each item in addresses will have a _prefetched_objects_cache dict containing a "person' key.
Note, both of these are single-underscore attributes which means they are part of the private API; you're free to use them, but Django is also free to change them in future releases.
Per this comment on the ticket linked in the comment by #jaap3 above, the recommended way to do this for Django 3+ (perhaps 2+?) is to use the undocumented is_cached method on the model's field, which comes from this internal mixin:
>>> person1 = Person.objects.first()
>>> Person.address.is_cached(person1)
False
>>> person2 = Person.objects.select_related('address').last()
>>> Person.address.is_cached(person2)
True
I have to tables wit similar fields and I want to copy objects from one table to another.
Problem that object could be absent in second table, so I have to use get_or_create() method:
#these are new products, they all are instances of NewProduct model, which is similar
#to Product model
new_products_list = [<NewProduct: EEEF0AP>, <NewProduct: XR3D-F>,<Product: XXID-F>]
#loop over them and check if they are already in database
for product in new_products_list:
product, created = Products.objects.get_or_create(article=product.article)
if created:
#here is no problem because new object saved
pass
else:
# here I need to code that will update existing Product instance
# with values from NewProduct instance fields
The case is that I don't want to list all fields for update manually, like this,, because I have about 30 of them:
update_old_product = Product(name=new_product.name,article= new_product.article)
Please advise more elegant way than above
You can loop over the field names and update them in the the other Product instance:
for new_product in new_products_list:
# use different variable names, otherwise you won't be able to access
# the item from new_product_list here
product, created = Products.objects.get_or_create(article=new_product.article)
if not created:
for field in new_product._meta.get_all_field_names():
setattr(product, field, getattr(new_product, field))
product.save()
You could try something like this.
def copy_fields(frm, to):
id = to.id
for field in frm.__class__._meta.fields:
setattr(to, field.verbose_name, field._get_val_from_obj(frm))
to.id = id
This is similar to Ashwini Chaudhary, although I think it will take care of that error that you mentioned in the comments.
new_products_list= (
# obj1, obj2, obj3 would be from [<NewProduct: EEEF0AP>, <NewProduct: XR3D-F>,<Product: XXID-F>] in your question
# NewProduct would just be the model that you import
# NewProduct._meta.fields would be all the fields
(obj1, NewProduct, NewProduct._meta.fields,),
(obj2, NewProduct, NewProduct._meta.fields,),
(obj3, NewProduct, NewProduct._meta.fields,),
)
for instance, model, fields in new_products_list:
new_fields = {}
obj, created = model.objects.get_or_create(pk=instance.article) # this is pretty much just here to ensure that it is created for filter later
for field in fields:
if field != model._meta.pk: # do not want to update the pk
new_fields[field.name] = request.POST[field.name]
model.objects.filter(pk=question_id).update(**new_fields) # you won't have to worry about updating multiple models in the db because there can only be one instance with this pk
I know this was over a month ago, but I figured I would share my solution even if you have already figured it out