[Line Bot] Linebot + Django Database 實作

• targets: Linebot + Django framework, database implementation.
• previous post: https://medium.com/@ycpin/line-bot-linebot-django
• Django official document

Django 包含一個簡單而強大的 ORM（物件關聯對映），ORM 為生成和管理資料庫遷移提供支援。Django 支援許多現成的關聯式資料庫，例如 SQLite、PostgreSQL、MySQL 和 Oracle。換句話說，若使用的是關聯式資料庫，則由於 Django 具備內建的 ORM 和遷移管理工具，入門將更加容易。

Overview

• Each model is a Python class that subclasses django.db.models.Model.
• Each attribute of the model represents a database field.
• With all of this, Django gives you an automatically-generated database-access API.

建立資料表：models.py

舉例 Person 資料，屬性為 first_name 以及 last_name：

from django.db import models

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

執行上述 Person model 將會創造一個資料表如下：

CREATE TABLE myapp_person (
    "id" bigint NOT NULL PRIMARY KEY GENERATED BY DEFAULT AS IDENTITY,
    "first_name" varchar(30) NOT NULL,
    "last_name" varchar(30) NOT NULL
);

同理，若我們想從 Linebot 中記錄用戶 ID 以及訊息內容：

from django.db import models

# Create your models here.
class user_message(models.Model):
    uid = models.CharField(max_length=50, null=False, primary_key=True)  # user id
    name = models.CharField(max_length=50, blank=True, null=False) # LINE 名字
    message = models.CharField(max_length=600, blank=True, null=False) # 文字訊息紀錄
    time = models.DateTimeField(auto_now=True) # 日期時間

    def __str__(self):
        return self.name # print the user name in terminal

• time = models.DateTimeField(auto_now=True)，當 auto_now 為 true 時，不僅意味著該欄位的預設值為當前時間，而是表示該欄位將被「強制」更新為當前時間，無法在程式中手動為該欄位賦值，且該欄位在管理員界面中是唯讀的。
• __str__(): A Python “magic method” that returns a string representation of any object. This is what Python and Django will use whenever a model instance needs to be coerced and displayed as a plain string. Most notably, this happens when you display an object in an interactive console or in the admin.

後台資料：admin.py

from models.py import the database table

from django.contrib import admin

# Register your models here.
from example.models import *

class user_message_admin(admin.ModelAdmin):
    list_display = ('uid', 'name', 'message', 'time')
admin.site.register(user_message, user_message_admin)

更新資料庫

python manage.py makemigrations
python manage.py migrate

資料表操作：views.py

將 models.py 資料表匯入 views.py

from example.models import *

修改 views.py 主要 codespace

if isinstance(event, MessageEvent):
    uid = event.source.user_id
    profile = line_bot_api.get_profile(uid)
    name = profile.display_name
    text = event.message.text

    message=[]
    if not user_message.objects.filter(uid=uid).exists():
        user_message.objects.create(uid=uid, name=name, message=text)
        message.append(TextSendMessage(text='資料新增完畢'))
    else:
        user_message.objects.filter(uid=uid, name=name).update(message=text, time=datetime.datetime.now())
        # obj = user_message.objects.get(uid=uid)
        # obj.message = text
        # obj.save()                
        message.append(TextSendMessage(text='資料修改完畢'))

    line_bot_api.reply_message(event.reply_token, message)

登入 http://127.0.0.1:8000/admin，資料新增成功

關於 DateTimeField 自動更新

• 操作經過 model 層，會自動更新 current time

obj = user_message.objects.get(uid=uid)
obj.message = text
obj.save()

• 使用 filter 的 update，因為直接調用 sql 語法，不通過 model 層，需呼叫 datetime.datetime.now() 函式更新

user_message.objects.filter(uid=uid, name=name).update(message=text, time=datetime.datetime.now())

Database CRUD (create, read, update, delete)

Create data:

Table_name.objects.create(data=data)

Read data:

# return list
Table_name.objects.filter(data=data)

# return only one object
Table_name.objects.get(data=data)

Update data:

Table_name.objects.filter(data=data, name=name).update(text=new_text)

Delete data:

Table_name.objects.filter(data=data).delete()
Table_name.objects.all().delete()

Github Repo

GitHub - ycpranchu/linebot_django_database: 使用 Linebot 結合 Django 後端，實作 Database。

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[Line Bot] Linebot + Django 實作