Django之同時新增數據到兩個資料庫表與同時返回兩個表的數據(插拔式)

• 2022 年 10 月 21 日
• 筆記
• django, Python, Python3

• models：比如有以下三個模型

from django.db import models

"""
基類，其他類繼承即可獲得對應的欄位
""" 
class BaseModel(models.Model):
    updated_tm = models.DateTimeField(auto_now=True)
    created_tm = models.DateTimeField(auto_now_add=True)

    class Meta:
        abstract = True

"""
項目列表
"""
class ProjectList( BaseModel):
    project_id = models.AutoField(help_text="項目ID", primary_key=True)
    project_name = models.SlugField(max_length=128, help_text="項目名稱", unique=True)

    class Meta:
        db_table = 'project_list'
        verbose_name = '項目列表資訊'
        verbose_name_plural = verbose_name

"""
項目詳情
"""
class ProjectDetail(BaseModel):
    project_introduction = models.CharField(max_length=128, help_text="用戶簡介")
    project_info = models.ForeignKey(to=ProjectList, on_delete=models.DO_NOTHING, db_constraint=False, related_name='user')

    class Meta:
        db_table = project_detail'
        verbose_name = '項目詳情資訊'
        verbose_name_plural = verbose_name

一、同時新增數據到兩個資料庫表

• views

from rest_framework import filters, mixins, generics
from rest_framework.viewsets import GenericViewSet


class ProjectListView(mixins.CreateModelMixin, GenericViewSet):
    queryset = Account.objects.filter(is_delete=0).all().order_by("-created_tm")

def create(self, request, *args, **kwargs):
    # 先定義兩個dict 
    project_list_dict = {}
    project_detail_dict = {}

    # 使用 ._meta.get_fields() 獲取資料庫表的全部欄位，再使用field.name獲取全部的欄位名稱，放入各自的dict，不存在的自動忽略掉
    for item in request.data.items():
        if item in [field.name for field in ProjectList._meta.get_fields()]:
            project_list_dict [item[0]] = item[1]
        elif item in [field.name for field in ProjectDetail._meta.get_fields()]:
            project_detail_dict [item[0]] = item[1]

    # 從上面的models可以看到，項目詳情與項目列表兩張表是有關聯的，所以，新增數據的時候，先現在列表，新增成功，生成ID後，再新增詳情，並通過ID與列表數據關聯起來
    # 檢查項目是否存在，項目名稱唯一約束，Serializer內設置必填
        try:
            # 存在就直接失敗
            ProjectList.objects.get(project_name=request.data.get('project_ame'))
            return xxx
        except Account.DoesNotExist:
            # 如果不存在，先調用ProjectList表新增數據
            try:
                project_create = ProjectList.objects.update_or_create(defaults=project_list_dict, project_name=project_list_dict["project_ame"])
                # 如果ProjectList表新增數據成功，則通過project_info，在ProjectDetail新增對應的數據
                if project_create:
                    project_id = ProjectList.objects.filter(project_name=project_list_dict["project_ame"]).values('project_id').first()
                    ProjectDetail.objects.update_or_create(defaults=project_detail_dict, project_info=project_id["project_id"])
                    return xxx
            except Exception as e:
                return e

二、同時返回兩個表的數據(插拔式)

• 插拔式的好處：即插即用，需要時才調用，不需要則不調用
• 從ProjectDetail這個models我們可以看到，是沒有定義project_id和project_name的，但我們是與ProjectList關聯的，所以，我們可以通過project_info，返回ProjectList已定義的project_id和project_name

# 我們只需要把ProjectDetail改成以下這樣子就可以了
class ProjectDetail(BaseModel):
    project_introduction = models.CharField(max_length=128, help_text="用戶簡介")
    project_info = models.ForeignKey(to=ProjectList, on_delete=models.DO_NOTHING, db_constraint=False, related_name='user')

    class Meta:
        db_table = project_detail'
        verbose_name = '項目詳情資訊'
        verbose_name_plural = verbose_name

    @property
    def  project_id(self):
        return self.project_info.project_id

    @property
    def  project_name(self):
        return self.project_info.project_name

# 然後在序列化器內直接調用project_id和project_name即可
class ProjectDetailSerializer(serializers.ModelSerializer):
    class Meta:
        model = ProjectDetail

        fields = ('project_id', 'project_name', 'project_introduction',)