How to create href link from one Django app to another

Question

I know this has been asked multiply times before, but I still don't get it.
How can I create a href-link in one Django app that sends the user to a 2nd app?

This is my setup:

myproject/
  manage.py
  myproject/
    __init__.py
    settings.py
    urls.py
    asgi.py
    wsgi.py

  app1/
    migrations/
    templates/
      app1/
        app1.html
    __init__.py
    admin.py
    apps.py
    models.py
    tests.py
    views.py

  app2/
    migrations/
    templates/
      app2/
        app2.html
    __init__.py
    admin.py
    apps.py
    models.py
    tests.py
    views.py

myproject/urls.py

from django.contrib import admin
from django.urls import path, include

urlpatterns = [
    path('admin/', admin.site.urls),
    path('app1/', include('app1.urls'), name='app1'),
    path('app2/', include('app2.urls'), name='app2'),
]

myproject/settings.py

INSTALLED_APPS = [
    'app1.apps.App1Config',
    'app2.apps.App2Config',
    'django.contrib.admin',
...
]

app1/urls.py (analogous for app2)

from django.urls import path
from . import views

urlpatterns = [
    path('', views.app1, name='app1'),
    ]

app1/views.py (analogous for app2)

from django.template import loader
from django.http import HttpResponse

def app1(request):
    template = loader.get_template('app1/app1.html')
    return HttpResponse(template.render())

app1/templates/app1/app1.html (analogous for app2)

<p>This is the template of app1.</p>
<a href="app2/">Go to App2</a> # doesn't work
<a href="app2/app2.html">Go to App2</a> # doesn't work
<a href="./app2/app2.html">Go to App2</a> # doesn't work

My problem is that this sends me to the address 127.0.0.1:8000/app1/app2/ which gives me a 404 error. However, I can access app2 via 127.0.0.1:8000/app2/ without a problem.

Edit:
Thanks everyone for your feedback. After going through your suggestions, I made the following changes:

myproject/urls.py:

from django.contrib import admin
from django.urls import path, include

urlpatterns = [
    path('admin/', admin.site.urls),
    path('app1/', include('app1.urls', namespace='app1')), # ADDED NAMESPACE
    path('app2/', include('app2.urls', namespace='app2')), # ADDED NAMESPACE
]

myproject/settings.py: no changes

app1/urls.py: (analogous for app2)

from django.urls import path
from . import views

app_name = 'app1' # THIS WAS MISSING
urlpatterns = [
    path('', views.app1, name='app1'),
    ]

app1/views.py: no changes

app1/templates/app1/app1.html: (analogous for app2)

<p>This is the template of app1.</p>
<a href="{% url 'app2:app2' %}">Go to App2</a> # AS SUGGESTED BY seif

Now it works.

Answer 1

When you input "127.0.0.1:8000/app1/app2/", django will recieve "app1/app2/" and work like below(not accurate):

1.compare app1/ to every element in urlpatterns of myproject/urls.py

so, app1/ will be found.

2.compare app2/ to every element in urlpatterns of app1.urls

there's nothing will be found, because there is only a "" in urlpatterns of app1.urls.

so you get a 404 page.

if you input "127.0.0.1:8000/app2/", in step 2, "" equals to "",

fuction views.app2 executes, and you get a correct page.

I suggest you read the django's tutorials in official site.

https://docs.djangoproject.com/en/3.1/intro/tutorial01/

Answer 2

in your template and views try not to hardcode the url of href instead use the {%url ''%} which will be {%url 'namespace:urlname'%}

<p>This is the template of app1.</p>
<a href="{% url 'app2:app2'%}">Go to App2</a>

this give you flexibility to change the path in your urls and not to worry about changing it at all your templates and views you can read more here https://docs.djangoproject.com/en/3.1/topics/http/urls/#reverse-resolution-of-urls

Answer 3

your href link doesn't go to the .html file in templates, templates are just for UI, and barely have a say in how you project gets routed, infact it depends on you to configure. instead it should go to the url specified in your url file,

so say your bases url is

path('app1/', include('app1.urls'), name='app1')

for one of your app it will be

<a href="example.com/app1">App 1</a>

if you have other links under app1 url file, it will then be

<a href="example.com/app1/myother-app1-link">A link under App 1</a>

example.com here, could be localhost:8000 or just localhost with any port, depending on the port your django project runs one.

then as for this,

from django.template import loader
from django.http import HttpResponse

def app1(request):
    template = loader.get_template('app1/app1.html')
    return HttpResponse(template.render())

I will suggest you do something like this instead

from django.shortcuts import render
from django.http import HttpResponse, HttpRequest

def app1(request,slug=None):
    return render(request,'app1/app1.html',{})
    #path to the template folder, under templates, depends on your configuration though

Kindly read more on templates configuration and routing in Django,but this should give a jumpstart.

Cheers