How to Execute Code Only Once at Django Startup?

Executing Code Once at Django Startup

Problem:

When implementing a Django middleware class intended to execute only once at startup to initialize additional code, the message "Hello world" is printed twice.

Solution:

For Django >= 1.7:

Use the ready() method in an AppConfig class:

<code class="python"># myapp/apps.py
class MyAppConfig(AppConfig):
    name = 'myapp'
    verbose_name = "My Application"

    def ready(self):
        # startup code goes here</code>

For Django < 1.7:

Place the startup code in the __init__.py file of any installed app:

<code class="python"># myapp/__init__.py
def startup():
    # startup code goes here

startup()

Explanation:

Using the ready() method in Django >= 1.7 ensures that the code is executed after Django has finished loading all models and migrations. For Django < 1.7, placing the code in the __init__.py ensures that it runs upon import, which occurs once per process.

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