How to retrieve the latest object added (new one) in Django models and display it in the template?

[Byansi Samuel]

Hey everyone, l got a problem. Am trying to retrieve a single latest object added everytime, and display it in the template.
Below is my codes but;

Help me figure it out the source of the problem in these different instances below 👇

_______________________ issue number 1_______

#Action/models.py
class ActionGame(models.Model):
        name=models.Charfield()
        published=models.DateTimeField()

#Action/views.py
from Action.models import ActionGame

def action (request):
        latest_action=ActionGame.objects.filter(published=published). latest()
Context={ 'latest_action': latest_action }
return....

But it returns *error* :
name 'published' is not defined

____________________ issue number 2________

#Action/models.py
class ActionGame(models.Model):
        name=models.Charfield()
        published=models.DateTimeField()
        class Meta:
              get_latest_by='published'

#Action/views.py
........
latest_action=ActionGame.objects. latest()
.......

#but it returns *error* :
'ActionGame' object is not iterable

Even if I try this:
............
latest_action=ActionGame.objects. latest('published')
.......

#it returns the Same error:
'ActionGame' object is not iterable

But this second issue, the error is referred in #action.html

{% for x in latest _action %}
<p>{{ x.game_name }}</p>
{% endfor %}

Please l need your assistance.

I'm Samuel,
Thanks

[Andréas Kühne]

Se comments below.

Den fre 24 feb. 2023 kl 12:14 skrev Byansi Samuel <samuelb...@gmail.com>:

Hey everyone, l got a problem. Am trying to retrieve a single latest object added everytime, and display it in the template.
Below is my codes but;

Help me figure it out the source of the problem in these different instances below 👇

_______________________ issue number 1_______

#Action/models.py
class ActionGame(models.Model):
        name=models.Charfield()
        published=models.DateTimeField()

#Action/views.py
from Action.models import ActionGame

def action (request):
        latest_action=ActionGame.objects.filter(published=published). latest()
Context={ 'latest_action': latest_action }
return....

But it returns *error* :
name 'published' is not defined

You haven't defined what the value of published is. If you want to get the last created one the query should be:
latest_action=ActionGame.objects.latest("published") - that would give you the last published item. Another way would be:
latest_action=ActionGame.objects.order_by("published").last()

 

____________________ issue number 2________

#Action/models.py
class ActionGame(models.Model):
        name=models.Charfield()
        published=models.DateTimeField()
        class Meta:
              get_latest_by='published'

#Action/views.py
........
latest_action=ActionGame.objects. latest()
.......

#but it returns *error* :
'ActionGame' object is not iterable

Even if I try this:
............
latest_action=ActionGame.objects. latest('published')
.......

#it returns the Same error:
'ActionGame' object is not iterable

But this second issue, the error is referred in #action.html

{% for x in latest _action %}
<p>{{ x.game_name }}</p>
{% endfor %}

So the latest_action variable that you have sent to the template is an instance of ActionGame - and not a list or anything. You can only access variables in the ActionGame class. For example:

 <p>{{ lastest_action.name }}</p>

would print out the value of the name of the ActionGame instance.

Please l need your assistance.

I'm Samuel,
Thanks

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[Dev Femi Badmus]

all_action=ActionGame.objects.all()

my_action = []

for action in all_action:

    my_action.append(action)

last_action = my_action[-1]

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[Andréas Kühne]

I'm sorry Dev, but that is really bad practice.

You are doing in python what can be done by the database. That type of code would create a memory error and be very slow to run. It's much better to get the last item from the database. In your example it would just be:
last_action = ActionGame.objects.last()

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[Michael Starr]

Regarding issue 2, (just to chime in):

You can get all objects to iterate over using a modification of get_context_data(), placed in the relevant view.

def get_context_data(self, *args, **kwargs):

        context = super().get_context_data(**kwargs)

        context['chosen_variable_name'] = <model object>.objects.all() <-- you can filter here! so: ... .objects.latest("published") or ... .objects.order_by("published").last()

        return context

Then iterate over 'chosen_variable_name' in the template file associated with this view. Remember to choose the association in the view using

template_name = "template to associate to.html"

Michael

[Byansi Samuel]

Hey thanks, but l tried to use ordering=('-published')

Se comments below.

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[Sandip Bhattacharya]

Your problem is still about where the 'published’ value is coming from in the call to filter(published=published).

Is it coming from a form? A Get parameter? A post parameter? Extract it appropriately before calling filter()

[Boris Pérez]

One way could be  latest_action=ActionGame.objects.filter(published=published).order_by('-id')[:1]

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