I want to show data from view in html. This is views.py

views.py

def addDeviceForm(request):

    key=request.GET['key']
    device=Device.objects.filter(key=key)
    data = {'device':device}
    return render(request,'add_form.html', data)

I try to show one data in html file like but it's not display value.

<b>{{ device.key }}</b>

If I show data with for like this code it have no problem.

{% for device in device %}
<b>{{ device.key }}</b>
{% endfor %}

I edit views.py like this.

    key="001"
    device=Device.objects.filter(key=key)
    data = {'device':device,'key':key }
    return render(request,'add_form.html', data)

And show in html like this.

{{ key.key }}

It still not show value.

Can I show one value in html without for loop?

CodePudding user response：

In template

# https://docs.djangoproject.com/en/4.0/ref/templates/builtins/#first
<b>{{ data.first.key }}</b>

OR

If you want to make a filter which returns nth item of your object then:

• In your app create a directory templatetags inside that directory create a file __init__.py and a file with any name filters.py

In filters.py

from django import template

register = template.Library()


@register.filter
def get_item(myList, index=0):
    """
    Django template filter to get nth item of list
    """
    if index < 0:
        return myList[0]
    else:
        return myList[index]

In template

The filter get_item can be used as: filters is the name of the file in templatetags

{% load filters %}
<!-- n will be item 0, 1, 2, ... -->
<b>{{ data|get_item:"n" }}

CodePudding user response：

def add_device_form(request):
    key=request.GET['key'] # you should probably use a FORM here 
    # device=Device.objects.filter(key=key) you don't need a queryset
    # and querysets are plural, they are a set of the rows, not a single row
    device = get_object_or_404(Device, key=key) # Throws 404 if obj doesn't exist
    context = {'device':device} 
    return render(request,'add_form.html', context)

CodePudding user response：

the filter method of a model class will always return a query set to you not an object if you want to return an object using the filter method you should use this:

device=Device.objects.filter(key=key).last()

or

device=Device.objects.filter(key=key).first()

this way you will get the last or first object of your queryset instead of itself.

CodePudding user response：

Yes, you can show one value in html, you must use get()^django-doc or better get_object_or_404()^django-doc.

views.py

from django.shortcuts import get_object_or_404, render


def addDeviceForm(request):

    key=request.GET['key']
    device=get_object_or_404(Device,any_key_name=key)
    data = {'device':device}
    return render(request,'add_form.html', data)

Then, in your template file you will get an object device in which you can access all its properties.

Template file

<b>{{ device.any_key_name }}</b>

Note: filter()^djano-doc always returns new QuerySet containing objects that match the given lookup parameters as stated in docs. So, only use it with looping, since you don't know whether database has 1 record or more.