I am looking for a way to retrieve a parent field during a query of the the children records. At this time I have the following example model.
class Record(models.Model):
event_title=models.CharField(max_length=500)
event_description=models.CharField(max_length=4000)
class SecondTable(models.Model):
event_code=models.ForeignKey(Record, default=0, on_delete=models.CASCADE)
wasfun=models.BoolField(default=True)
When I view the values of the queryset and select_related below, the values from the parent don't seem to be included (i.e. event_description). However, the .query property shows all the fields being selected.
SecondTable.objects.all().select_related("event_code").values()
Is there a way to see all values from the joined tables? Sorry for a newbie question. Thanks!
I think not in only one line, but you can try with next:
values_second_table = [s.name for s in SecondTable._meta.fields]
values_first_table = ['event_code__{}'.format(r.name) for r in Record._meta.fields]
my_values = values_second_table + values_first_table
SecondTable.objects.all().select_related("event_code").values(*my_values)
Related
class Country(Models.Model):
code = models.CharField(max_length=50)
name = models.CharField(max_length=500)
class Meta:
unique_together = (('code', 'name'),)
db_table = 'md_country'
class UserSettings(models.Model):
...
default_countries = models.ManyToManyField(Country, db_table='user_default_countries', related_name='default_countries')
I have two models inside django models, what im trying is when i add Country models to default_countries i want to preserve order. Currently when i append manytomany field django automatically sort by Country name (alphabetical order)
I have this code
# iterate one by one to preserve fetching order
country_models = [Country.objects.get(id=_id) for _id in request.data[default_countries]]
user_settings.default_countries.clear()
for c in country_models:
user_settings.default_countries.add(c)
After this when i inspect user_settings.default_countries i have ordered countries by name in alphabetical order.
I want to preserve when adding element. If i want to add France and Australia and i order the list like that i on the end when i pull data from db i want it to be ordered like that. Now on this example i have Australia then France.
EDIT:
I checked the database and when inserting the data, it insert in right order
For example if i want France(73) then Australia(13), France has smaller id so its inserted first. There is a problem with django when pulling the data from database.
So as I understand correct you want to sort by insert order:
someSetting = UserSettings.objects.first()
countries = someSetting.default_countries.order_by('id')
I found the workaround.
Firstly i defined new property inside model where default_countries is.
#property
def ordered_default_countries(self):
return self.default_countries.all().order_by('-id')
Then in serializer where i serialize this field i just pointed default_countries field to ordered_default_countries.
I'm trying to understand how can I define model as a class containing 2 integers and 1 charfield and then make it a part of another model.
Example of data I need
I guess in object oriented programming I should define model class like this:
class Component(models.Model):
pipe_type = models.CharField(max_length=200)
length = models.IntegerField()
amount = models.IntegerField()
And then I don't know how can I use it with django models, it should be something like this:
class Item(models.Model):
name = models.CharField()
components_needed = ? LIST OF Component class ?
Also, since components needed size will wary for objects, it should be possible to extend it's size with button on a page, for example there could be 3 input fields and next to them would be "+" and "-" button to add/remove another set of 3 input fields
I spent entire day looking for solution, but at this point I'm not sure if django can handle this. I'm new to python and django, so there are many things I do not understand.
I will be grateful for any kind of help
the only way now( you canot put multi FK in one cell) is like django itself using with user/groups so you need 3 models.
in django there is group, user and user_group so i suggesting for you:
class Component(models.Model):
pipe_type = models.CharField(max_length=200)
length = models.IntegerField()
amount = models.IntegerField()
class Item(models.Model):
name = models.CharField()
class Item_Component(models.Model):
Component = models.ForeignKey(Component, on_delete=models.CASCADE)
Item = models.ForeignKey(Item, on_delete=models.CASCADE)
so now in third model you can have multiple rows with item and with diffrent component.
open yours db viewer app and see django user_group table.
I'm new to Flask and have started designing a front end for an inventory management database using Flask-AppBuilder.
I have created several models and have have managed to display my sqlite data in tables using Flask-AppBuilder's views.
However, I don't seem to be able to find the equivalent of SQLite WHERE clause to filter or "restrict" column data. I've been reading a lot about sqlalchemy, filters, queries but this has left me more confused that anything else and the explanations seem to be extremely elaborate and complicated to do something which is extremely simple.
Assuming we reproduce the following SQLite query in Flask-AppBuilder:
SELECT Field_A
FROM Table_A
WHERE Field_A = 'some text'
with:
result = session.query(Table_A).filter_by(Field_A = 'some text').all()
Where does the above line of code go in my app?
Considering I have the following Class:
class Table_A(Model):
id = Column(Integer, primary_key=True)
Field_A = Column(String)
def __repr__(self):
return self
and View:
class Table_AView(ModelView):
datamodel = SQLAInterface(Table_AView)
label_columns = {'Field_A':'A'}
list_columns = ['Field_A']
After much digging flask-appbuilder uses it's own filterclass in order to enable you to filter your views.
All the classes are referenced here on GitHub:
Flask Filter Clases List
Also not the difference between FilterEqual and FilterEqualFunction here:
What is the difference between : FilterEqual and FilterEqualFunction?
For other customisation and first port of call of Flask-appbuilder go straight to the API Reference where you'll find a couple of examples of the filterclass in action.
In essence it is extremely simple. In your views.py code within the ModelView class you want to filter simply add base_filters = [['field_A', FilterEqual, 'abc']] like so:
`class Table_AView(ModelView):
datamodel = SQLAInterface(Table_AView)
label_columns = {'Field_A':'A'}
list_columns = ['Field_A']
base_filters = [['field_A', FilterEqual, 'abc']]`
This will only show the lines where the field_A variable is equal to abc.
Hope this helps someone as it took me nearly (sigh) two weeks to figure it out...
SQLALchemy is an ORM (Object-Relational Mapping), it mean that you dont have to deal with raw SQL, you will call a function that you "build" (by adding filters in your case). It will transparently generate an SQL query, execute it, and return the result as python objects.
I would suggest you to read closely at sqlalchemy documentation about filters again, especially filter_by :
http://docs.sqlalchemy.org/en/latest/orm/query.html#sqlalchemy.orm.query.Query.filter_by
It is the easiest way to apply a WHERE with sqlalchemy.
If you have declared correctly the model for Table_A, you should be able to use it so:
result = session.query(Table_A).filter_by(Field_A = 'some text').all()
Here session.query(Table_A).filter_by(Field_A = 'some text') will generate the SQL, and .all() will execute it.
I am slowly progressing in my django journey, but this one has me stumped. I am trying to populate a CreateView with a different model via a copy command using the get_initial override. All of the attributes copy as I would expect with the exception of the ManytoMany fields. I've researched this topic most of today, and found the following which is very close to what I'm trying to figure out KeyError: 'manager' in django get_initial.
My View...
class BookView(LoginRequiredMixin,CreateView):
model = Book
template_name = 'book/titles.html'
form_class = BookForm
def get_initial(self):
initial = super(BookView, self).get_initial()
author = author.objects.get(pk=self.kwargs["pk"])
initial = author.__dict__.copy()
initial.update({
"author": author.name,
}}
for field in self.form_class.base_fields.items():
value = getattr(self.get_object(), field)
if field == 'author':
value = self.get_object().author.all()
initial.update({field: value})
return initial
I incorporated the suggested change based on the issue that I found on SO, but I still am getting a 'manager" KeyError. I am ultimately trying to populate the manytomanyfield in my model and then save the values, but to no avail. Any suggests are appreciated!
What a difference a day makes....
def get_initial(self):
initial = super(BookView, self).get_initial()
author = author.objects.get(pk=self.kwargs["pk"])
initial = author.__dict__.copy()
initial.update({
"author": author.name.all(),
}}
return initial
I added a .all() after the reference to the manytomanyfield in my initial get and also update the form to get the field in question. Much cleaner than a few hacks I kinda got working along the way.
I want to facet the results based on the different model_names (classes) returned. Is there an easy way to do this?
Have you tried adding a SearchIndex field with this information? E.g.
class NoteIndex(SearchIndex, indexes.Indexable):
title = CharField(model_attr='title')
facet_model_name = CharField(faceted=True)
def get_model(self):
return Note
def prepare_facet_model_name(self, obj):
return "note"
class MemoIndex(SearchIndex, indexes.Indexable):
title = CharField(model_attr='title')
facet_model_name = CharField(faceted=True)
def get_model(self):
return Memo
def prepare_facet_model_name(self, obj):
return "memo"
And so on, simply returning a different string for each search index. You could also create a mixin and return the name of the model returned by get_model too.
Presuming you've added this field to each of your SearchIndex definitions, just chain the facet method to your results.
results = form.search().facet('facet_model_name')
Now the facet_counts method will return a dictionary with the faceted fields and count of results for each facet value, in this case, the model names.
Note that the field here is labeled verbosely to avoid a possible conflict with model_name, a field added by Haystack. It's not faceted, and I'm not sure if duplicating it will cause a conflict.
If you just want to filter on the model type, you can use the ModelSearchForm
The Docs have a really good walk-through for this.
The minimum you'll need:
is to add faceted=True to the params of your model_names field.
Rebuild your schema and indices.
add .facet('model_names') to whatever SearchQuerySet you're wanting to facet.
More explanation on the question would enable a more complete answer.