Hi, you can use aggregation queries to count the child images connected to
each server:
# views.py
from django.db.models import Count
def servers(request):
servers = Server.objects.all()
for server in servers:
server.child_images = server.images.aggregate(total=Count('base'))
return render(request, "administration/servers.html", {'servers':
servers})
# template
{% for server in servers %}
<h1>Server: {{ server }}</h1>
No. images: {{ server.images.count }}<br/>
No. child images: {{ server.child_images.total }}
{% endfor %}
https://docs.djangoproject.com/en/1.10/topics/db/aggregation/
('child_image' would be a more suitable related_name than 'base')
Also, if server--image is a ManytoMany relation and an image can have many
child images, the ForeignKey relation here between Childimage and Server
would currently seem redundant/inaccurate.
More broadly, if all child images are types of images, you could consider
making ChildImage a subclass of Image instead, ie. class ChildImage(Image):
which might help with querying, as then you could just count child images
with server.childimage_set.count(), (if you removed the current
related_name for Childimage.server).
On Tuesday, August 16, 2016 at 1:22:28 AM UTC+1, Wolf Painter wrote:
>
> Hey everyone, I didn't see any posts (or google search) that could
> possibly answer my question, so I am here... I'm trying to create a way to
> launch vm's on a Xen or VMWare server using a website. I have the python
> file written on the Server and am currently creating a DJango app to manage
> everything. I'm stuck in a big way. I currently have models that track
> servers, images and child images launched from the parent, but I can't
> figure out how to display it properly in a template so i can update the
> count (either add or subtract a number of VM's from a server). I'm new to
> both Django and Python, so please excuse any ignorance here... Here are my
> relevant models:
>
> class Image(models.Model):
> name = models.CharField(verbose_name='Image Name', max_length=50)
> labID = models.ManyToManyField(Lab, blank=True, related_name='labID')
> type = models.CharField(max_length=50)
>
> def __str__(self):
> return self.name
>
>
> class Server(models.Model):
> name = models.CharField(verbose_name='Server Name', max_length=50)
> ipAddress = models.CharField(max_length=15)
> maxCCU = models.IntegerField(default=0)
> images = models.ManyToManyField(Image, blank=True,
> related_name='baseImage')
>
> def __str__(self):
> return self.ipAddress
>
> class Childimage(models.Model):
> name = models.CharField(verbose_name='Child Image Name', max_length=50)
> parent = models.ForeignKey(Image, related_name='base')
> server = models.ForeignKey(Server, related_name='server')
> inUse = models.BooleanField()
> rdpportnum = models.CharField(max_length=4)
>
> def __str__(self):
> return self.name
>
> What I'm trying to do is have a web page that displays the number of parent
> images on a server by counting the child image. For example, I have a parent
> image called win2k12_excel and there are 12 child images of the parent
> win2k12_excel on the x.x.x.x server. I would like a web page that shows there
> are 12 win2k12_excel images on that server that would allow me to add or
> subtract the number on that server.
>
>
> I have created a view that does this and puts it into a multidimensional
> dictionary, but I cannot figure out how to get that to render properly in a
> template. Here is my view:
>
>
> def servers(request):
> serverlist = Server.objects.all()
> imagelist = Image.objects.filter(baseImage__in=serverlist).distinct()
>
> childimagelist = defaultdict(list)
> for server in serverlist:
> for image in imagelist:
> number =
> Childimage.objects.filter(parent__name__contains=image).filter(server__ipAddress__contains=server).count()
> childimagelist[server].append({image: number})
> childimagelist.default_factory = None
> context = {
> "server_list": serverlist,
> "image_list": imagelist,
> "child_list": childimagelist
> }
> return render(request, "administration/servers.html", context)
>
> No matter what I have tried so far, I cannot get this dictionary to render in
> a template. Is there a better way to do what I'm trying to do? Is there a
> proper way to get the dictionary parsed in the template? Any help would be
> appreciated.
>
>
> Oh, and I have search Google for weeks and tried all the suggestions I found.
> None of them worked. I can get the first part of the dictionary parsed, but
> no further than that. Here is the template code (server works, but for image,
> number in images.items, does not):
>
>
> {% for server, images in child_list.items %}
> <h1>{{ server }}</h1>
> {% for image, number in images.items %}
> <h1>{{ number }}</h1>
> {% endfor %}
> {% endfor %}
>
>
>
> Any help at all would be appreciated...
>
>
> Thanks,
>
> Wolf
>
>
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