Hello Simon,
I tried implementing your recommendations today and all appeared to go well
except that I was not getting any results from the query for remaining
seating on the html template. I took a look at my reservation table and the
data was gone. I had the data in an original table I copied from and tried
to do the same but now have the following error....
INSERT INTO restaurant_reservation (id, seats_reserved, event_id, user_id)
SELECT winery_event_reservation_id, winery_event_adult_seats_reserved,
event_id, user_id FROM winery_event_reservations;
ERROR 1452 (23000): Cannot add or update a child row: a foreign key
constraint fails (`campodibella`.`restaurant_reservation`, CONSTRAINT
`restaurant_reservati_event_id_d13deeb7_fk_restauran` FOREIGN KEY
(`event_id`) REFERENCES `restaurant_wineryevents` (`id`))
I went through all the migrate/makemigrations/migrate operations too.
Here is my FROM table structure...
mysql> describe winery_event_reservations;
+------------------------------------+------------------+------+-----+-------------------+-----------------------------+
| Field | Type | Null | Key |
Default | Extra |
+------------------------------------+------------------+------+-----+-------------------+-----------------------------+
| winery_event_reservation_id | int(10) unsigned | NO | PRI |
NULL | auto_increment |
| event_id | int(10) | YES | |
NULL | |
| user_id | int(10) | YES | |
NULL | |
| winery_event_adult_seats_reserved | int(10) | YES | |
NULL | |
| winery_event_child_seats_reserved | int(10) | YES | |
NULL | |
| winery_event_reservation_timestamp | timestamp | NO | |
CURRENT_TIMESTAMP | on update CURRENT_TIMESTAMP |
+------------------------------------+------------------+------+-----+-------------------+-----------------------------+
Copied TO table...
mysql> describe restaurant_reservation;
+----------------+------------------+------+-----+---------+----------------+
| Field | Type | Null | Key | Default | Extra
|
+----------------+------------------+------+-----+---------+----------------+
| id | int(11) | NO | PRI | NULL | auto_increment
|
| user_id | int(11) | NO | | NULL |
|
| seats_reserved | int(10) unsigned | NO | | NULL |
|
| event_id | int(11) | NO | MUL | NULL |
|
+----------------+------------------+------+-----+---------+----------------+
4 rows in set (0.00 sec)
I did rename some fields and tables here is my current setup..
MODELS
class WineryEvents(models.Model):
event_date = models.DateField(auto_now_add=False)
event_time = models.TimeField(auto_now_add=False)
event_type = models.CharField(max_length=20, choices=EVENT_TYPE)
seating = models.PositiveIntegerField(default=0)
title = models.CharField(max_length=200)
description = models.TextField()
menu = models.TextField()
price = models.DecimalField(max_digits=6, decimal_places=2)
publish = models.CharField(max_length=1, choices=PUBLISH_CHOICE)
def __int__(self):
return self.title
class Reservation(models.Model):
user_id = models.IntegerField(default=0)
event = models.ForeignKey(WineryEvents, related_name='reservations',
on_delete=models.PROTECT)
seats_reserved = models.PositiveIntegerField(default=0)
def __int__(self):
return self.event
VIEW
def winery_events_view(request):
winery_events =
WineryEvents.objects.filter(publish='Y').filter(event_date__gte=datetime.now()).order_by('event_date')
WineryEvents.objects.annotate(
seats_remaining = F('seating')-Sum('reservations__seats')
)
return render(request,
'restaurant/winery_events.html',{"winery_events":winery_events, })
TEMPLATE
....
{% for i in winery_events %}
<div class='first-column'>
<h3 style='display:inline;'>{{ i.event_date|date:"l M j, Y" }} {{
i.event_time|date:"g:i A" }}</h3><br>
<p style='display:inline;'>{{i.event_type|title}} -
{{i.title|title}}</p><br>
<a style='display:inline;' href="{% url 'make_reservation' pk=i.pk
%}">Purchase Reservation ${{i.price}}</a> <p style='display: inline;'>Seats
Remaining {{i.seats_remaining}}</p>
<p> {{ i.description|safe}} </p>
</div>
....
Any further help would be greatly appreciated. Thanks in advance.
Marc
On Friday, September 7, 2018 at 10:08:07 AM UTC-5, Simon Charette wrote:
>
> The annotate(seats_remaining=...) will add a `seats_remaining` attribute
> to Event
> instances returned from the queryset so you should be able to use
> {{i.seats_remaining }}
>
> Cheers,
>
> Le vendredi 7 septembre 2018 04:38:05 UTC-4, mab.mo...@gmail.com a écrit :
>>
>> Thank you Simon.
>>
>> I will take a look at annotations.
>>
>> How would I represent seats remaining in the template for loop? Here is
>> what I have so far.....
>>
>> #####################
>>
>> {% for i in events %}
>>
>> <div class='first-column'>
>> <h3 style='display:inline;'>{{ i.event_date|date:"l M j, Y" }} {{
>> i.event_time|date:"g:i A" }}</h3><br>
>> <p style='display:inline;'>{{i.event_type|title}} -
>> {{i.title|title}}</p><br>
>> <a style='display:inline;' href="{% url 'make_reservation' pk=i.pk
>> %}">Purchase Reservation ${{i.price}}</a> <p style='display: inline;'>Seats
>> Remaining ### VARIABLE HERE ###</p>
>> <p> {{ i.description|safe}} </p>
>> </div>
>>
>> <div class='second-column' style="background-image:
>> url('../static/restaurant/images/event_images/{{i.id}}.jpg');
>> background-size: cover;">
>> </div>
>>
>> <div class='first-column' style="height:10px; border: 0px solid
>> black;">
>> </div>
>>
>> <div class='second-column' style="height:10px; border: 0px solid
>> black;">
>> </div>
>>
>> {% endfor %}
>>
>>
>> #####################
>>
>>
>>
>> On Thursday, September 6, 2018 at 8:04:36 AM UTC-5, Simon Charette wrote:
>>>
>>> Hello there,
>>>
>>> You should be able to achieve what you're after by using annotations[0].
>>>
>>> In your case you'll want to declare your Event and Reservation
>>> relationship explicitly by using
>>> a ForeignKey
>>>
>>> class Event(models.Model):
>>> ...
>>> seating = models.PositiveIntegerField(default=0)
>>>
>>> class Reservation(models.Model):
>>> ...
>>> event = models.ForeignKey(Event, related_name='reservations')
>>> seats = models.PositiveIntegerField(default=0)
>>>
>>> And perform the following query
>>>
>>> Event.objects.annotate(
>>> seats_remaining=F('seating') - Sum('reservations__seats').
>>> )
>>>
>>> Cheers,
>>> Simon
>>>
>>> [0]
>>> https://docs.djangoproject.com/en/2.1/topics/db/aggregation/#generating-aggregates-for-each-item-in-a-queryset
>>>
>>> Le jeudi 6 septembre 2018 07:42:36 UTC-4, mab.mo...@gmail.com a écrit :
>>>>
>>>>
>>>> QUESTION
>>>>
>>>> I have an application that will make on-line reservations for a series
>>>> of weekly events. I would like to display the list of upcoming events in
>>>> an
>>>> html template with the number of remaining seats available in a single
>>>> html
>>>> page. I was able to create views to display the list of upcoming events
>>>> and
>>>> another view to display the number of remaining seats available but I am
>>>> unable to figure out how to nest the two into a single view. Example
>>>> below...
>>>>
>>>> HTML OUTPUT
>>>>
>>>> Event Title Week 1 - x amount of seats remaining for this event
>>>>
>>>> Event Title Week 2 - x amount of seats remainign for this event
>>>>
>>>> Event Title Week 3 - x amount of seats remaining for this event
>>>>
>>>> and so on ....
>>>>
>>>> MODELS
>>>>
>>>> class Events(models.Model):
>>>> event_date = models.DateField(auto_now_add=False)
>>>> event_time = models.TimeField(auto_now_add=False)
>>>> event_type = models.CharField(max_length=20, choices=EVENT_TYPE)
>>>> seating = models.IntegerField(default=0)
>>>> title = models.CharField(max_length=200)
>>>> description = models.TextField()
>>>> menu = models.TextField()
>>>> price = models.DecimalField(max_digits=6, decimal_places=2)
>>>> publish = models.CharField(max_length=1, choices=PUBLISH_CHOICE)
>>>>
>>>> def __int__(self):
>>>> return self.title
>>>>
>>>> class Reservations(models.Model):
>>>> user_id = models.IntegerField(default=0)
>>>> event_id = models.IntegerField(default=0)
>>>> reservations = models.IntegerField(default=0)
>>>>
>>>> def __int__(self):
>>>> return self.event
>>>>
>>>>
>>>> VIEWS
>>>>
>>>> def events_view(request):
>>>>
>>>> events=Events.objects.filter(publish='Y').filter(event_date__gte=datetime.now()).order_by('event_date')
>>>>
>>>> reservation_count = Reservations.objects.aggregate(Sum('reservations'))
>>>>
>>>> return render(request, 'restaurant/events.html',{"events":events,
>>>> "reservation_count":reservation_count, })
>>>>
>>>> def make_reservation_view(request, pk):
>>>> event = Events.objects.get(id=pk)
>>>> seating_available = Events.objects.get(id=pk)
>>>> seating_available = seating_available.seating
>>>> reservation_count =
>>>> Reservations.objects.filter(event_id=pk).aggregate(res_sum=Sum('reservations'))
>>>> res = reservation_count['res_sum']
>>>> seats_remaining = seating_available - res
>>>>
>>>> return render(request, 'restaurant/make_reservation.html',
>>>> {"event":event, \
>>>>
>>>> "seats_remaining":seats_remaining,})
>>>>
>>>>
>>>>
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