Cannot retrieve foreign key ID - django

Question

I am building an application that allows a user to create a scenario, then create associated emails, t, calls and trades to the scenario.
There is a 1:many relationship with the scenario and the communications. The issue I am having is I want the user to be able to click the scenario, it then shows the filtered list of communications, each communication source is a tab. The way I am filtering the communication is based on the id of the foreign key on the object. However if there is no entry for the datasource I receive a "no reverse match" because I am using the scenario id from the first object and that doesnt exist if there is no communication for that scenario.
I am stumped on what the best way to do this, besides removing tabs which I like.
Please let me know if I am missing anything, I am relatively new to programming and very new to Django.
models.py
from __future__ import unicode_literals
from django.db import models
from django.core.urlresolvers import reverse
class Scenario(models.Model):
name = models.CharField(max_length=256, blank=False, null=False, unique=True)
description = models.TextField(max_length=1000)
def get_absolute_url(self):
return reverse('scenarios:detail', kwargs={'pk': self.pk})
def __unicode__(self):
return self.name
class Email(models.Model):
scenario = models.ForeignKey(Scenario, on_delete=models.CASCADE )
recipient_email = models.EmailField()
sender_email = models.EmailField()
subject = models.CharField(blank=True, null=False, max_length=256)
body = models.TextField(blank=True, null=False, max_length=2048)
# timestamp = models.DateTimeField(auto_now_add=True, auto_now=False)
# updated = models.DateTimeField(auto_now_add=False, auto_now=True)
def get_absolute_url(self):
return reverse('scenarios:email-index')
def __unicode__(self):
return self.sender_email + ' ' + self.recipient_email + ' ' + self.subject
class InstantMessage(models.Model):
NETWORKS = (
('Yahoo', 'Yahoo'),
('MSN', 'MSN'),
('Skype', 'Skype')
)
scenario = models.ForeignKey(Scenario, on_delete=models.CASCADE)
description = models.CharField(max_length=256, null=False, blank=False)
network = models.CharField(max_length=50, null=False, blank=False, choices=NETWORKS)
room = models.CharField(max_length=100, null=False, blank=False)
starttime = models.TimeField(blank=False, null=False)
endtime = models.TimeField(blank=False, null=False)
participant1 = models.CharField(max_length=256, null=False, blank=False)
participant2 = models.CharField(max_length=256, null=False, blank=False)
chatcsv = models.FileField(upload_to='chatfiles')
def get_absolute_url(self):
return reverse('scenarios:im-index')
def __unicode__(self):
return "Network=" + self.network + " Description:" + self.description
class VoiceCall(models.Model):
DIRECTION = (
('outbound', 'Outbound'),
('inbound', 'Inbound')
)
scenario = models.ForeignKey(Scenario, on_delete=models.CASCADE)
description = models.CharField(max_length=256, null=False, blank=False)
direction = models.CharField(choices=DIRECTION, null=False, blank=False, default="Outbound", max_length=15)
starttime = models.TimeField(blank=False, null=False)
endtime = models.TimeField(blank=False, null=False)
traderid = models.CharField(max_length=50,blank=False, null=False)
diallednumber = models.BigIntegerField(blank=True, null=True)
cli = models.BigIntegerField(blank=True, null=True)
nameofcaller = models.CharField(max_length=100, blank=True, null=True)
nameofline = models.CharField(max_length=100, blank=True, null=True)
wavfile = models.FileField(upload_to='voice')
transcript = models.FileField(blank=True, null=True, upload_to='voice')
bagofwords = models.FileField(blank=True, null=True, upload_to='voice')
def get_absolute_url(self):
return reverse('scenarios:call-index')
def __unicode__(self):
return self.description
class Trade(models.Model):
scenario = models.ForeignKey(Scenario, on_delete=models.CASCADE)
tradeprefix = models.CharField(max_length=6, null=False, blank=False)
trader = models.CharField(max_length=256, null=False, blank=False)
sales = models.CharField(max_length=256, null=False, blank=False)
counterpartyid = models.CharField(max_length=256, null=False, blank=False)
counterpartyname = models.CharField(max_length=256, null=False, blank=False)
brokerid = models.CharField(max_length=256, null=False, blank=False)
brokername = models.CharField(max_length=256, null=False, blank=False)
isevent = models.BooleanField(default=False)
def get_absolute_url(self):
return reverse('scenarios:trade-index')
# def __unicode__(self):
# return self.description
class Mobile(models.Model):
scenario = models.ForeignKey(Scenario, on_delete=models.CASCADE)
displayname = models.CharField(max_length=100, null=False, blank=False)
email = models.EmailField()
tonumber = models.BigIntegerField(blank=True, null=True)
fromnumber = models.BigIntegerField(blank=True, null=True)
message = models.CharField(blank=True, null=False, max_length=1024)
def get_absolute_url(self):
return reverse('scenarios:mobile-index')
views.py
class IMScenarioList(generic.ListView):
model = InstantMessage
template_name = 'scenarios/im_filtered.html'
context_object_name = 'scenario_ims'
def get_queryset(self):
return InstantMessage.objects.filter(scenario=self.kwargs['pk'])
class CallScenario(generic.ListView):
model = VoiceCall
template_name = 'scenarios/call_filtered.html'
context_object_name = 'scenario_calls'
def get_queryset(self):
return VoiceCall.objects.filter(scenario=self.kwargs['pk'])
class MobileScenario(generic.ListView):
model = Mobile
template_name = 'scenarios/mobile_filtered.html'
context_object_name = 'scenario_mobiles'
def get_queryset(self):
return Mobile.objects.filter(scenario=self.kwargs['pk'])
class TradeScenario(generic.ListView):
model = Trade
template_name = 'scenarios/trades_filtered.html'
context_object_name = 'trades'
def get_queryset(self):
return Trade.objects.filter(scenario=self.kwargs['pk'])
urls.py
url(r'^(?P<pk>[0-9]+)/email/$', views.EmailScenarioList.as_view(), name='email-scenario'),
# Instant Messages
url(r'^im/$', views.IMList.as_view(), name='im-index'),
url(r'^im/add/$', views.IMCreate.as_view(), name='im-create'),
url(r'^im/(?P<pk>[0-9]+)/update/$', views.IMUpdate.as_view(), name='im-update'),
url(r'^im/(?P<pk>[0-9]+)/delete/$', views.IMDelete.as_view(), name='im-delete'),
url(r'^(?P<pk>[0-9]+)/im/$', views.IMScenarioList.as_view(), name='im-scenario'),
# Voice Calls
url(r'^calls/$', views.CallList.as_view(), name='call-index'),
url(r'calls/add/$', views.CallCreate.as_view(), name='call-create'),
url(r'^calls/(?P<pk>[0-9]+)/update/$', views.CallUpdate.as_view(), name='call-update'),
url(r'^calls/(?P<pk>[0-9]+)/delete/$', views.CallDelete.as_view(), name='call-delete'),
url(r'^(?P<pk>[0-9]+)/voice/$', views.CallScenario.as_view(), name='call-scenario'),
# trades
url(r'^trades/$', views.TradeList.as_view(), name='trade-index'),
url(r'^trades/add/$', views.TradeCreate.as_view(), name='trade-create'),
url(r'^trades/(?P<pk>[0-9]+)/update/$', views.TradeUpdate.as_view(), name='trade-update'),
url(r'^trades/(?P<pk>[0-9]+)/delete/$', views.TradeDelete.as_view(), name='trade-delete'),
url(r'^(?P<pk>[0-9]+)/trade/$', views.TradeScenario.as_view(), name='trade-scenario'),
# mobile
url(r'^mobile/$', views.MobileList.as_view(), name='mobile-index'),
url(r'^mobile/add/$', views.MobileCreate.as_view(), name='mobile-create'),
url(r'^mobile/(?P<pk>[0-9]+)/update/$', views.MobileUpdate.as_view(), name='mobile-update'),
url(r'^mobile/(?P<pk>[0-9]+)/delete/$', views.MobileDelete.as_view(), name='mobile-delete'),
url(r'^(?P<pk>[0-9]+)/mobile/$', views.MobileScenario.as_view(), name='mobile-scenario'),
Templates
trade_index.html
{% extends 'base.html' %}
{% block content %}
<div class="container">
<table id="myTable" class="tablesorter tablesorter-bootstrap">
<thead>
<tr>
<th class="first-name filter-select" data-placeholder="Select a Scenario">Scenario</th>
<th></th>
<th>Trade Prefix</th>
<th>Trader</th>
<th>Sales</th>
<th>Counterparty ID</th>
<th class="first-name filter-select" data-placeholder="Select Counterparty">Counterparty Name</th>
<th>Broker ID</th>
<th></th>
<th class="first-name filter-select" data-placeholder="Select Broker">Broker Name</th>
<th class="first-name filter-select" data-placeholder="IsEvent">IsEvent</th>
<th>Edit</th>
<th>Delete</th>
</tr>
</thead>
<tbody>
{% for trade in trades %}
<tr>
<td data-toggle="tooltip" title="Description: {{trade.scenario.description}}">{{trade.scenario}}</td>
<td></td>
<td>{{trade.tradeprefix}}</td>
<td>{{trade.trader}}</td>
<td>{{trade.sales}}</td>
<td>{{trade.counterpartyid}}</td>
<td>{{trade.counterpartyname}}</td>
<td>{{trade.brokerid}}</td>
<td></td>
<td>{{trade.brokername}}</td>
<td>{{trade.isevent}}</td>
<td>
<a href="{% url 'scenarios:trade-update' trade.id %}">
<button type="submit" class="btn btn-default btn-sm">
<span class="glyphicon glyphicon-pencil" />
</button>
</a>
</td>
<td><form action="{% url 'scenarios:trade-delete' pk=trade.id %}" method="post">
{% csrf_token %}
<input type="hidden" name="call_id" value="{{ trade.id}}"/>
<button type="submit" class="btn btn-default btn-sm" onclick="return confirm('Are you sure you want to delete {{trade.description}}?')">
<span class="glyphicon glyphicon-trash" />
</button>
</form>
</td>
</tr>
{% endfor %}
</tbody>
</table>
<a href="{% url 'scenarios:trade-create' %}">
<button type="submit" class="btn btn-default btn-sm">
<span class="glyphicon glyphicon-plus" />
</button>
</a> Add Trade
<br>
<button type="button" class="btn btn-default btn-sm" value="Back" onClick="javascript:history.go(-1);">
<span class="glyphicon glyphicon-backward" />
</button>
</div>
{% endblock %}
trades_filtered.html
{% extends 'scenarios/trade_index.html' %}
{% block content %}
{% with trades|first as first_trade %}
<ul class="nav nav-pills">
<li class="active">trades</li>
<li>emails</li>
<li>instant messages</li>
<li>voice</li>
<li>mobile</li>
</ul>
{% endwith %}
{{ block.super }}
{% endblock %}

Answer 1

Right now in trades_filtered.html you take the ID of a given scenario and use that ID to manually construct your five URLs. If it were me, I'd use a custom model method to determine whether or not we need to generate a URL first.
class Scenario(models.Model):
name = models.CharField(max_length=256, blank=False, null=False, unique=True)
description = models.TextField(max_length=1000)
def generate_trade_url(self):
if self.trade_set.exists():
return reverse('scenarios:trade-scenario', kwargs={'pk':self.pk})
return None
def generate_email_url(self):
...
You would need one method like this for each URL you want to generate. You can this use this logic either in the view (preferable) or in your template (simpler but slower) to dynamically generate your URLs only when they are valid.
EDIT: I just looked at this answer a second time. I included null=False in the name field definition because it was in the original, but be aware that it doesn't actually do anything useful on a CharField. Django doesn't use null values for those fields, instead storing them as '' (empty string).