Django community: Django Q&A RSS
This page, updated regularly, aggregates Django Q&A from the Django community.
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Django - TypeError: object of type 'NoneType' has no len() occurred while doing Pagination
TypeError: object of type 'NoneType' has no len() occurres when I'm adding a pagination to a list view. Error: I want to allow users to search for books by entering a book title or an author name or a publisher name. I have three if statements below for fetching data in one of any these three situations. The last return statement is for returning an empty query set when a user enters an invalid key word for searching. book/views: class SearchResultView(generic.ListView): template_name = 'book/search.html' model = Book context_object_name = 'book_list' paginate_by = 2 def get_queryset(self): queryset = super().get_queryset() search = self.request.GET.get('search') if search: books_with_title = queryset.filter(title__icontains=search) if len(books_with_title) > 0: return books_with_title books_with_author = queryset.filter(authors__name=search) if len(books_with_author) > 0: return books_with_author books_with_publisher = queryset.filter(publisher__name=search) if len(books_with_publisher) > 0: return books_with_publisher return queryset.filter(title='no result found') # empty queryset for showing 'No result found.' on web pages I'm not sure whether I made the pagination correct or not (I can't test it due to the error) , I mean the href attribute. Cos I have no idea how to use the {% url 'some_view' %} for href in this case. If I did it wrong, please let me know or correct it. ... -
Filtering and grouping in Python Model Objects after queryng the datbase
I have the following model: class Item(models.Model): user = models.ForeignKey(settings.AUTH_USER_MODEL, blank=True, null=True, related_name='item',on_delete=models.SET_NULL) email = models.BooleanField(blank=True, null=True) ..... I need to send an email to user, where Item email attribute is False. I have the following query: items = Item.objects.filter(email=False) I want to filter/group item by User. I want to do it python because I want to send emails with delay and not to overwhelm the database at once with many queries. For each use I want to create a context dictionary that I can sent to the Django Email. -
Celery + Django on startup
I have written a code with django and celery, it is for a machine to run some tasks and to be accessible through net. So I need the django and celery to run automatically when the built-in PC starts. Can anyone please tell me the best and easiest way to do this? Can servers like Apache handle such thing? -
Python / Django pdfkit wkhtmltopdf UnknownContentError
I'm getting an UnknownContentError when generating a PDF document from a project URL (https://ourcodeworld.com/articles/read/241/how-to-create-a-pdf-from-html-in-django) - using pdfkit (wkhtmltopdf). pdf = pdfkit.from_url('http://127.0.0.1:8000/cb/open_detailed_research_outputs/', False, options) The URL is valid and displays the way it should in the browser. Could someone please advise where I'm going wrong. [Other URLs in my web app project seem to work except for this one.] Further error info: wkhtmltopdf reported an error: Loading pages (1/6) [> ] 0% [======> ] 10% [=======> ] 13% [==============================> ] 50% Error: Failed to load http://127.0.0.1:8000/cbib/open_detailed_research_outputs/, with network status code 299 and http status code 500 - Error downloading http://127.0.0.1:8000/cbib/open_detailed_research_outputs/ - server replied: Internal Server Error [============================================================] 100% Counting pages (2/6) [============================================================] Object 1 of 1 Resolving links (4/6) [============================================================] Object 1 of 1 Loading headers and footers (5/6) Printing pages (6/6) [> ] Preparing [============> ] Page 1 of 5 [========================> ] Page 2 of 5 [====================================> ] Page 3 of 5 [================================================> ] Page 4 of 5 [============================================================] Page 5 of 5 Done Exit with code 1 due to network error: UnknownContentError Request Method: POST Request URL: http://127.0.0.1:8000/cbib/open_detailed_research_outputs/download/ Django Version: 2.0.2 Exception Type: OSError Exception Value: wkhtmltopdf reported an error: Loading pages (1/6) [> ] 0% [======> ] 10% ... -
user-defined function raised exception occurred
I have following error when I'm using below user defined function with raw query: Django Version: 2.1 Exception Type: OperationalError Exception Value: user-defined function raised exception from django.db.backends.signals import connection_created from django.dispatch import receiver @receiver(connection_created) def extend_sqlite(connection=None, **kwargs): if connection.vendor == "sqlite": # sqlite doesn't natively support math functions, so add them cf = connection.connection.create_function cf('acos', 1, math.acos) cf('cos', 1, math.cos) cf('radians', 1, math.radians) cf('sin', 1, math.sin) Here are is my raw query. query = """SELECT id, (6367*acos(cos(radians(%2f)) *cos(radians(lat))*cos(radians(long)-radians(%2f)) +sin(radians(%2f))*sin(radians(lat)))) AS distance FROM ksApp_outlet group by id having distance < %2f """ % ( float(lat), float(lng), float(lat), float(radius) ) outletdata = Outlet.objects.raw(query) Not sure what I'm doing wrong here. Can any one help me to figure out this error? -
Django form not getting submitted after first ajax call
On the page i have a drop down (when i change selected option, first ajax gets fired). First ajax is working fine and page is updating. After updating page, I have an add button on UI, upon clicking which second ajax is fired. It should submit the form. But Add button ajax (second ajax) is working only if i have not run the first ajax. Second ajax is not even getting called if I have run first ajax before it. I suspect there is some CSRF token issue here. Second ajax gets called if I don't run first ajax before. First ajax: var topicId = $(".topic_select option:selected").attr("data-topic"); $(".topic_select").change(function(){ var topicId = $(".topic_select option:selected").attr("data-topic"); if (topicId == undefined){ topicId = 999999; }; $.ajax({ type: "GET", url: "{% url 'recruiter:add_question_library' %}", data: { topicId: topicId, }, success: function(response){ // alert("Showing questions from topic " + topicId); $("#question_list").replaceWith($("#question_list",response)); } }); }); Second Ajax: $('.add-question-form').on('submit',function(e){ alert("hh"); e.preventDefault(); var $this = $(this); var qstn_id = $this.attr('id').split('_')[1]; $.ajax({ type: "POST", url: "{% url 'recruiter:add_question_to_interview' %}", data: { qstn_id: qstn_id, 'csrfmiddlewaretoken': '{{ csrf_token }}', }, success: function(response){ // $("#question-alert").animate({right: '20%'}, "slow"); // $('#question-alert').append('<div class="alert alert-success alert-dismissible fade show" role="alert"><strong>Question added to interview</strong><button type="button" class="close" data-dismiss="alert" aria-label="Close"><span aria-hidden="true">&times;</span></button></div>'); ... -
How to access Google Analytics in django admin panel?
I have a doubt how to google analytics dispaly in django admin panel.can give any suggestion or give proper documentation.I see many documentation cant understand .can give any example code.I tried but its not working can give proper documentation or any code.I tried api key also is not working . -
How can I add field to reqeust body in django middleware
I want to add new field in request body in middleware and use it in views. I googled it but the results was not worked. How can I do it ? Django v2 python 3.6 -
Django ORM multiple distinct and order by
I work on a simple chat app. I need to query db for an user to get last message of user conversation to other users. Same as main page of whatsapp and telegram. Model: class CHAT(models.Model): sender_uid = models.CharField(max_length=150, db_index=True) receiver_uid = models.CharField(max_length=150, db_index=True) message = models.TextField(verbose_name='Message Text') created = models.IntegerField(default=created_time_epoch) I tried this query: message_list = self.model.objects.filter(Q(sender_uid=user_uid)|Q(receiver_uid=user_uid)).order_by('receiver_uid', 'sender_uid', '-created').distinct('receiver_uid', 'sender_uid') Output: <QuerySet [<CHAT: ted@ted.com Message: hello 4 To: saeed@saeed.com>, <CHAT: marshal@marshal.com Message: hello6 To: saeed@saeed.com>, <CHAT: saeed@saeed.com Message: hello 5 To: ted@ted.com>]> My problem is I get two last message from each conversation (if both user send message to each other), In one of them user is sender and in other one user is receiver. For now I handle it with below code: message_send_list = list(self.model.objects.filter(sender_uid=user_uid).order_by('receiver_uid', '-created').distinct('receiver_uid')) message_receive_list = list(self.model.objects.filter(receiver_uid=user_uid).order_by('sender_uid', '-created').distinct('sender_uid')) temp_list = [] for s_message in message_send_list: r_message = next((item for item in message_receive_list if item.sender_uid == s_message.receiver_uid), None) if r_message is not None: message_receive_list.pop(message_receive_list.index(r_message)) if s_message.created > r_message.created: temp_list.append(s_message) else: temp_list.append(r_message) else: temp_list.append(s_message) temp_list.extend(message_receive_list) Output: [<CHAT: saeed@saeed.com Message: hello 5 To: ted@ted.com>, <CHAT: marshal@marshal.com Message: hello6 To: saeed@saeed.com>] My question is how can I get this result in one query? Problem is user can be sender and ... -
Get the FK attributes of a model , if a model is passed
I have the following Model(s): class Comp(models.Model): .... is_active = models.BooleanField(default=False) class Item(models.Model): comp = models.ForeignKey(Comp, blank=True, null=True, related_name='items', on_delete=models.CASCADE) romp = models.ForeignKey(Romp, blank=True, null=True, related_name='items', on_delete=models.CASCADE) is_active = models.BooleanField(default=False) I want to write a generic Model clean method,to check for non Null Foreign Keys of a Model, if their is_active=True I want to inherit this method over multiple Models(using abstract Model) In the code below I check each model attribute over a general list of FKs def clean(self, *args, **kwargs): .... for attr in FK_LIST: if hasattr(self, attr): fk_obj = getattr(self, attr) if not fk_obj.active: raise ValidationError({'is_active': 'The {} {} needs to be active first' .format(type(fk_obj).__name__, fk_obj.name)}) There 2 issues with my code: I have two manually maintain a list of FKs name I need to loop thru all attributes instead of checking just FKs Instead of having an implicit FK_list to check in, I prfer to have an exclude list(easy to maintain): Check all FK on the model that are not NULL or in Exclude_list -
Multithreading using queues in django + uWSGI
I am struggling to make Python standard queues work in uWSGI master. Sample code: import queue, threading, time from django.apps import AppConfig my_queue = queue.Queue() class MyApp(AppConfig): def ready(self): thread1 = threading.Thread(target=process_queue, args=()) thread1.daemon = True thread1.start() thread2 = threading.Thread(target=poll, args=()) thread2.daemon = True thread2.start() def poll(): while True: time.sleep(1) logging.info("Polling works every time") def process_queue(): while True: logging.info("I get here") email = my_queue.get(block=True, timeout=None) logging.info("I NEVER GET here. **I would like to get here**") def put(): # I call this from the django views on requests my_queue.put("1") Both threads start. Thread 2 prints at regular intervals as expected. Thread 1 waits on the queue forever, even though I add to it from main thread (As part of Django requests, inside the views) My uWSGI config: [uwsgi] master = true module = backend.wsgi processes = 1 thunder-lock = true enable-threads = true socket = /tmp/django.sock chmod-socket = 666 vacuum = true Notice that if I run uWSGI with master = false, everything works as expected Additional information: I am running this as a vassal. The emperor is not running as master I do not really understand pre/post forking in django + uWSGI. This could be an issue This works if ... -
Understanding Image Fields, MEDIA_ROOT & MEDIA URL
Building of neverwalkaloner's answer here, I tried migrating my image model attribute from a CharField to an ImageField and then setting MEDIA ROOT & MEDIA URL in settings.py. My understanding, reading the documentation: here (how Django handles files), here (what does MEDIA URL and MEDIA ROOT mean), and here (what ImageField is and its different arguments), Django will handle the absolute path to the file of the particular ImageField based of the upload_path & settings. So I tested it in the shell. So far, it isn't working. UPDATED ATTEMPT AT PRODUCT In settings.py: MEDIA_ROOT = BASE_DIR + '/project' + '/media/' MEDIA_URL = '/media/' In models.py: from django.db import models class Product(models.Model): sku = models.CharField(validators=[isalphanumeric], max_length=20, null=False, blank=False) image = models.CharField(upload_to="products/" max_length=20, blank=False, null=False) Testing it out in the Python Django shell: In [1]: from app.models import Product In [2]: test_product = Product(sku='alphanumeric23', image='test_product.png') In [3]: test_product.log.path Out [3]: 'C:\\Users\\user\\path\\to\\project\\project\\media\\test_product.png' But my expected output should have been: 'C:\\Users\\user\\path\\to\\project\\project\\media\\product\\test_product.png' Is it because there's an assumption that it hasnt technically been uploaded yet (triggered by the test_product.save() (I'm assuming)? Something feels off. -
Pagination Django Class Based View Not Working Properly
I'm trying to use Django (v2.0) pagination with CBV and got issues. The pagination is active because the tag {% if is_paginated %} returns "True" and shows the "PagNav" and the browser path changes too, like this (..?page=1, ...?page=2, etc...) but the displayed elements are all, not 3 just as I set in "paginate_by=3". For example, if the query has 15 elements must to show 3 elements per page and 1 to 5 in the pagination down bellow, but shows all elements. I attach an image and the code: models.py: from django.db import models from django.contrib.auth.models import User from ckeditor.fields import RichTextField # Create your models here. class Project(models.Model): user = models.ForeignKey(User, on_delete = models.CASCADE, default=1) name = models.CharField(verbose_name='Nombre del proyecto', max_length=200) client = models.CharField(verbose_name='Nombre del cliente', max_length=200) description = RichTextField(verbose_name='Descripción') start = models.DateField(verbose_name='Fecha de Inicio', null=True, blank=True) ending = models.DateField(verbose_name='Fecha de Finalización', null=True, blank=True) order = models.SmallIntegerField(verbose_name="Orden", default=0) created = models.DateTimeField(verbose_name='Fecha de creación', auto_now_add=True) updated = models.DateTimeField(verbose_name='Fecha de modificación', auto_now=True) class Meta: verbose_name = 'Proyecto' verbose_name_plural = 'Proyectos' ordering = ['-start', 'order'] def __str__(self): return self.name class Album(models.Model): project = models.ForeignKey(Project, verbose_name='Proyecto relacionado', on_delete = models.CASCADE) title = models.CharField(verbose_name='Título de la imagen', max_length=200) image = models.ImageField(verbose_name='Imagen', upload_to='portfolio') created = ... -
Images gallery for Django
I'm new in Django world. I would like to create an image field in a model in wich if I want to add an image on a post(for example an header image) it's shown to me the list of image already used for other posts. If the image is not present already I can upload it. I think to a system like Wordpress media gallery. It's possible to create a similar system? Link for the study are appreciated. -
How to make type=“number” to positive numbers only using ember js
It was only preventing negative numbers from being entered from up/down arrows, whereas user can type negative number from keyboard. <div class="col-sm-2"> <label>Quantity</label><br> {{input type="number" value=quantity min="0" class="form-control- invoice"}} </div> -
Filter by user is not staff using Q in another model queryset
I have the following model: class APC(models.Model): user = models.ForeignKey(settings.AUTH_USER_MODEL, blank=True, null=True, related_name='apc', on_delete=models.SET_NULL) type= models.CharField(choices=TYPE_CHOICES, max_length=5, blank=True, null=True) I want to get APC objects that have one of two specific types, and user is not staff. I'm starting with: apcs = APC.objects.filter( ~Q(user is staff), Q(type=TYPE_CHOICES_A) | Q(type=TYPE_CHOICES_B) ) -
Django ORM select, concat, extract from data and order by
I'm having trouble performing a simple transformation with the django orm. Desired outcome should look like this: 2018-08 2018-07 2018-06 ... And is created with this sql: select distinct strftime('%Y',a."Buchung") || "-" || strftime('%m',a."Buchung") as YearMonth from hhdata_transaktion a order by 1 desc I need it for a ModelChoiceField as queryset, so I'm bound to the ORM here? My try from django.db.models.functions import TruncMonth, TruncYear Transaktion.objects .annotate(year=TruncYear('Buchung'), month=TruncMonth('Buchung')) .distinct() .order_by('-year', '-month') .values('year','month') returns: <QuerySet [{'year': datetime.date(2018, 1, 1), 'month': datetime.date(2018, 8, 1)}, {'year': datetime.date(2018, 1, 1), 'month': datetime.date(2018, 7, 1)}, {'year': datetime.date(2018, 1, 1), 'month': datetime.date(2018, 6, 1)}, {'year': datetime.date(2018, 1, 1), 'month': datetime.date(2018, 5, 1)}, {'year': datetime.date(2018, 1, 1), 'month': datetime.date(2018, 4, 1)}, {'year': datetime.date(2018, 1, 1), 'month': datetime.date(2018, 3, 1)}, {'year': datetime.date(2018, 1, 1), 'month': datetime.date(2018, 2, 1)}, {'year': datetime.date(2018, 1, 1), 'month': datetime.date(2018, 1, 1)}, {'year': datetime.date(2017, 1, 1), 'month': datetime.date(2017, 12, 1)}, {'year': datetime.date(2017, 1, 1), 'month': datetime.date(2017, 11, 1)}, {'year': datetime.date(2017, 1, 1), 'month': datetime.date(2017, 10, 1)}, {'year': datetime.date(2017, 1, 1), 'month': datetime.date(2017, 9, 1)}, {'year': datetime.date(2017, 1, 1), 'month': datetime.date(2017, 8, 1)}]> I have the feeling I'm miles away from the desired result.. -
How to create 'terms & conditions check box' in django?
I want to make a registration form like this, where user would type username,email,password,confirm password and check the terms and condition box to register his/herself. But i dont know how to create a model row for check box so that according to its input i would allow or disallow user to register. models.py class registeration(models.Model): username = models.CharField(max_length=100) email = models.EmailField() password = models.CharField(max_length=100) confirm_pasword = models.CharField(max_length=100) def __str__(self): return self.username -
are there any way to aggregate multiple API result into single API in Django Rest Framework?
I have following url set which return json API. Now I wonder are there any way to create another API which aggregate all of these API result and return to one ajax call from client side lets say,url(r'^api/allData/(?P<pk>\d+)$',allData.as_view()) Does anyone know how to prepare class in views.py to achieve this? urlpatterns = [ url(r'^api/envelope/(?P<pk>\d+)$',envelopeData.as_view(),name='api-envelope'), url(r'^api/glass/(?P<pk>\d+)$',glassData.as_view(),name='api-glass'), url(r'^api/opaque/(?P<pk>\d+)$',opaqueData.as_view(),name='api-opaque'), url(r'^api/plant/(?P<pk>\d+)$',plantData.as_view(),name='api-plant'), url(r'^api/fan/(?P<pk>\d+)$',fanData.as_view(),name='api-fan'), url(r'^api/pump/(?P<pk>\d+)$',pumpData.as_view(),name='api-pump'), url(r'^api/people/(?P<pk>\d+)$',peopleData.as_view(),name='api-people'), url(r'^api/light/(?P<pk>\d+)$',lightData.as_view(),name='api-light'), url(r'^api/smallpower/(?P<pk>\d+)$',spData.as_view(),name='api-sp'), ] -
How to add string to a ModelSerializer in Django REST
In my database, I store the file name of a particular image for an item. Let's say this is the model in models.py from django.db import models class Product(models.Model): sku = models.CharField(validators=[isalphanumeric], max_length=20, null=False, blank=False) image = models.CharField(max_length=20, blank=False, null=False) and then I have a serializer defined like so in serializers.py from rest_framework import serializers from app.models import Product class ProductSerializer(serializer.ModelSerializer): class Meta: model = Product fields = '__all__' what I want is to be able to add a string to the image of a Product that makes it into a string representing the relative link, something like: storage_location = '/assets/img' img_url = f'{storage_location}/{image}' The reason why I want to do this is because I want to be flexible with the urls rather than having the file name be a "file location" and then having to update the database each time I change how I arrange my images (I'm still not sure how to store them). How can I do that? -
Apache 2.4 giving error "Forbidden You don't have permission to access /static/ on this server" while deploying Django on Fedora
I am new to django and facing this forbidden error while deploying django on apache. I have tried almost all the solutions available on google but still didn't get over this issue. Currently I am using: Python3.6 Apache 2.4 Fedora 28 I also tried moving my project into /var/www but that also doesn't work for me. This is how my httpd.conf file looks. <VirtualHost *:80> ServerName rohit.com DocumentRoot /home/rohit/django_ionic/ ServerAdmin root@localhost Alias /static /home/rohit/django_ionic/drfx/static <Directory "/home/rohit/django_ionic/drfx/static"> Options Indexes FollowSymLinks Allow from all Require all granted </Directory> <Directory /home/rohit/django_ionic/drfx/drfx> Options Indexes FollowSymLinks Includes ExecCGI AllowOverride All Order allow,deny Allow from all Require all granted </Directory> WSGIDaemonProcess mysite1 python-path=/home/rohit/django_ionic/drfx:/usr/lib/python3.6/site-packages WSGIProcessGroup mysite1 WSGIScriptAlias / /home/rohit/django_ionic/drfx/drfx/wsgi.py WSGIApplicationGroup %{GLOBAL} <Directory /home/rohit/django_ionic/drfx/drfx/> <Files wsgi.py> Allow from all Require all granted </Files> </Directory> </VirtualHost> i have also given the chown permissions to my django file folder. One more issue is my user and group is apache and i have seen a alot of solutions using user and group as www-data:www-data. Is that realy making any difference as i have given permissions by using apache:apache. -
How to fix the parentheses problem in this python coding?
function generate_map(){ $(".error").hide(); var map_position = $('#map_position')[0].value; var map_distance = $('#map_distance')[0].value; var to_date = $('.date_to')[0].value; var from_date = $('.date_from')[0].value; if($("#rbRouteOnly").is(':checked')){ $.ajax({ type: 'POST', url: '/generateMap', data: JSON.stringify( { 'position': map_position, 'distance': map_distance, 'to_Date' : to_date, 'from_Date' : from_date, } ), contentType: "application/json; charset=utf-8", dataType:'json', error:function(error){ alert("error Occured please try again later"); }, success: function (res) { // var jsonresult =$.parseJSON(result) // error if((res.result).length == 0){ $('.graph_data_error').show(); $('#movement_category')[0].innerHTML = ""; }else{ console.log(res.result); var graph_data = res.result; var dps1 = [], dps2 = [], dps3 = [], dps4 = [], dps5 = [], dps6 = []; var chart = new CanvasJS.Chart("movement_category",{ title:{ text: "TIME vs. Movement category" }, axisX:{ title: "TIME SLOT" }, axisY:{ title: "% of Movement Category" }, toolTip: { shared: true }, data: [ { type: "stackedArea100", name: "In Vehicle", showInLegend: "true", yValueFormatString: "#,##0.##\"%\"", dataPoints: dps1 }, { type: "stackedArea100", name: "On Bicycle", showInLegend: "true", yValueFormatString: "#,##0.##\"%\"", dataPoints: dps2 }, { type: "stackedArea100", name: "On foot", showInLegend: "true", yValueFormatString: "#,##0.##\"%\"", dataPoints: dps3 }, { type: "stackedArea100", name: "Standstill", showInLegend: "true", yValueFormatString: "#,##0.##\"%\"", dataPoints: dps4 }, { type: "stackedArea100", name: "Tilting", showInLegend: "true", yValueFormatString: "#,##0.##\"%\"", dataPoints: dps5 }, { type: "stackedArea100", name: "Unknown", showInLegend: "true", yValueFormatString: "#,##0.##\"%\"", dataPoints: dps6 } ... -
I want Django orm to find difference in days between current date and a date time field from dB table
The my SQL query shown in the below. I want Django orm for Below query. select greatest((30-ifnull(DATEDIFF(CURRENT_DATE(),disabled_on),0)),0) AS unblock_days from tbl_users; Note: 'disabled_on' datetime(6) DEFAULT NULL -
Django - how to pass a value from an existing HTML form to a list view
I have an existing HTML form (text field + button) but have no idea how to pass an input value to a list view. book/templates/home.html: <form class="form-inline my-2 my-lg-0" method="post">{% csrf_token %} <input style="font-size: 12px; width: 200px" class="form-control mr-sm-2" type="search" placeholder="Book Name" aria-label="Search"> <button class="btn btn-outline-primary my-2 my-sm-0" type="submit">Search</button> </form> Image of the form: book/views/SearchResultView: class SearchResultView(generic.ListView): template_name = 'book/search.html' model = Book paginate_by = 100 As in creation views and update views or any other edit views, there will be an attribute called form_class, but not for display views. What can I do to achieve the goal? -
Django Sql: no such function: Decimal
I have the following query RecipePosition.objects.all().filter(mass_quantity__gt=0) In Django, try to debug the file /lib/python3.6/site-packages/django/db/models/sql/compiler.py to know how the sql is formed. def execute_sql(self, result_type=MULTI, chunked_fetch=False, chunk_size=GET_ITERATOR_CHUNK_SIZE): """ Run the query against the database and return the result(s). The return value is a single data item if result_type is SINGLE, or an iterator over the results if the result_type is MULTI. result_type is either MULTI (use fetchmany() to retrieve all rows), SINGLE (only retrieve a single row), or None. In this last case, the cursor is returned if any query is executed, since it's used by subclasses such as InsertQuery). It's possible, however, that no query is needed, as the filters describe an empty set. In that case, None is returned, to avoid any unnecessary database interaction. """ result_type = result_type or NO_RESULTS try: sql, params = self.as_sql() if not sql: raise EmptyResultSet At the below statement i checked the sql and params: sql, params = self.as_sql() sql = SELECT "recipes_recipeposition"."id", "recipes_recipeposition"."name", "recipes_recipeposition"."quantity", FROM "recipes_recipeposition" WHERE "recipes_recipeposition"."quantity" > %s and params = <class 'tuple'>: (Decimal('0'),) I tried the sql in sqlite browser: SELECT "recipes_recipeposition"."id", "recipes_recipeposition"."name", "recipes_recipeposition"."quantity", FROM "recipes_recipeposition" WHERE "recipes_recipeposition"."quantity" > Decimal('0') then it says no such function: Decimal
