在django中使用celery

JhonSmith發表於2019-02-16
Django

前言: 針對高延時任務, 直接在一次網路請求中處理完畢會導致很不好的體驗, celery則可以不阻塞請求後臺處理這些任務, 並且可以使用django的models進行資料庫操作.

環境

python models:

  • celery-4.1.1
  • redis-2.10.6
  • django-1.11.7

其他:

  • redis-3.2.9
  • macos
  • python3.6

建立django工程

django-admin startproject dc
cd dc
django-admin startapp main

此時專案結構如下

dc
|-- __init__.py
|-- main
|   |-- __init__.py
|   |-- admin.py
|   |-- apps.py
|   |-- migrations
|   |   `-- __init__.py
|   |-- models.py
|   |-- tests.py
|   `-- views.py
|-- settings.py
|-- urls.py
`-- wsgi.py

修改settings.py, 新增app

INSTALLED_APPS = [
    `django.contrib.admin`,
    `django.contrib.auth`,
    `django.contrib.contenttypes`,
    `django.contrib.sessions`,
    `django.contrib.messages`,
    `django.contrib.staticfiles`,
    `dc.main` //new added
]

修改dc/main/models.py, 建立新models

from django.db import models

# Create your models here.

class Person(models.Model):
    first_name = models.CharField(max_length=30)
    last_name = models.CharField(max_length=30)

建立根訪問節點

dc/main/views.py

from django.shortcuts import render
from django.http import HttpResponse
# Create your views here.


def hello(request):
    return HttpResponse(`hello world`)

dc/urls.py

urlpatterns = [
    url(r`^admin/`, admin.site.urls),
    url(r`^$`, hello) //new added
]

依次執行以下語句, 初始化django各功能模組

python manage.py migrate
python manage.py makemigrations main
python manage.py sqlmigrate main 0001
python manage.py migrate

接下來python manage.py runserver, 訪問http://127.0.0.1:8000 即可看到hello world.

啟動redis

redis是作為celery中介軟體使用的, 用來儲存訊息佇列.

redis解壓後, 直接執行src/redis-server即可啟動, 預設埠6379

配置celery

參考文件

建立dc/celery.py

#-*- coding:utf-8 -*-

import os
from celery import Celery

# set the default Django settings module for the `celery` program.
os.environ.setdefault(`DJANGO_SETTINGS_MODULE`, `dc.settings`)

app = Celery(`dc`)

# Using a string here means the worker doesn`t have to serialize
# the configuration object to child processes.
# - namespace=`CELERY` means all celery-related configuration keys
#   should have a `CELERY_` prefix.
app.config_from_object(`django.conf:settings`, namespace=`CELERY`)

# Load task modules from all registered Django app configs.
app.autodiscover_tasks()

修改 dc/__init__.py

from .celery import app as celery_app

__all__ = [`celery_app`]

修改 dc/settings.py, 設定 redis URL

CELERY_BROKER_URL = `redis://127.0.0.1:6379/3`

建立dc/main/tasks.py

#-*- coding:utf-8 -*-

from celery import shared_task

@shared_task
def test():
    import time
    time.sleep(5)
    from dc.main.models import Person
    person = Person(first_name=`smith`, last_name=`jhon`)
    person.save()
    c = Person.objects.count()
    print(f`person count is {c}`)

修改dc/main/views.py

def hello(request):
    from dc.main.tasks import test
    test.delay()
    return HttpResponse(`hello world`)

啟動celery程式

celery -A dc worker -l info

接下來訪問http://127.0.0.1:8000, 即可發現頁面立刻返回, 並沒有被time阻塞, 檢視啟動celery的視窗, 即可發現log以及列印的資訊, 確定models可以正常使用.

おわり.

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