有了产品信息之后，下面来写库存信息部分

每一个库存的入库和出库都需要对应一个产品，所以产品信息是它的外键

库存信息

创建App

python manage.py startapp warehouse

将warehouse文件夹移动到backend/apps/warehouse

注册App

在backend/LightSeeking/settings.py的INSTALLED_APPS中添加

INSTALLED_APPS = [...'users.apps.UsersConfig','product.apps.ProductConfig','warehouse.apps.WarehouseConfig'
]

表结构设计

库存信息包含了

• 产品信息

• 单价

• 生产日期

• 保质期天数

• 数量

• 库存状态

• 订单号

• 供应商

• 备注

产品信息使用外键的方式，并且两个键之间不互相影响

product = models.ForeignKey(Product, verbose_name="产品信息", on_delete=models.DO_NOTHING, help_text="产品信息")

其他都是普通的字段

from django.db import modelsfrom product.models import Product
from utils.models import BaseModelclass Warehouse(BaseModel):STOCKSTATUS = ((1, "入库"),(2, "出库"),(3, "报废"),)product = models.ForeignKey(Product, verbose_name="产品信息", on_delete=models.DO_NOTHING, help_text="产品信息")price = models.DecimalField('成本单价', max_digits=10, decimal_places=2, default=0, help_text='成本单价')date_of_manufacture = models.DateTimeField("生产日期", help_text="生产日期")quality_guarantee = models.IntegerField("保质期天数", help_text="保质期天数")num = models.IntegerField("数量", default=0, help_text="数量")stock_status = models.CharField("库存状态", max_length=2, choices=STOCKSTATUS, default=1,help_text='库存状态:1-入库,2-出库,3-报废')order_id = models.CharField("订单号", max_length=200, null=True, blank=True, default='', help_text='订单号')supplier = models.CharField("供应商", max_length=200, null=True, blank=True, default='', help_text='供应商')desc = models.CharField('备注', max_length=1000, null=True, blank=True, default='', help_text='备注')class Meta:db_table = 'tb_warehouse'verbose_name = '库存信息'verbose_name_plural = verbose_namedef __str__(self):return self.id

数据迁移

python manage.py makemigrations
python manage.py migrate

序列化器

在库存序列化器中需要指定产品来进行新增，查看的时候需要返回全部的产品信息

所以先新建一个包含全部产品的序列化器

backend/apps/product/serializers.py

class ProductAllModelSerializer(serializers.ModelSerializer):class Meta:model = Productfields = '__all__'

添加产品的时候使用的是产品的id，这时候就需要判断一下这个产品是否存在了

编写whether_existed_product_id方法来进行判断

def whether_existed_product_id(value):"""检查产品id是否存在:param value::return:"""if value != 0:if not isinstance(value, int):raise serializers.ValidationError('所选产品信息有误!')elif not Product.objects.filter(is_delete=False, id=value).exists():raise serializers.ValidationError('所选产品信息不存在!')

所以库存的序列化器基础版本为

class WarehouseModelSerializer(serializers.ModelSerializer):product_id = serializers.IntegerField(write_only=True,help_text='产品信息ID',validators=[validates.whether_existed_product_id])product = ProductAllModelSerializer(read_only=True, many=False)class Meta:model = Warehouseexclude = ('is_delete',)extra_kwargs = {'c_time': {'read_only': True},}

重点

下面是序列化器中的一个神奇的操作，也就是它可以逐行处理返回的数据，根据逻辑给每行添加需要的数据

在这个序列化器中需要顺便计算一下产品的保质期相关数据

新加两个字段剩余天数、保质期日期

剩余天数 = 保质期天数 - (当前日期 - 生产日期)

保质期日期 = 生产日期+剩余天数

remaining = serializers.SerializerMethodField(label="剩余天数", read_only=True, help_text="剩余天数")
remaining_day = serializers.SerializerMethodField(label="保质期日期", read_only=True, help_text="保质期日期")

使用serializers.SerializerMethodField可以在WarehouseModelSerializer类中编写get_xxx方法来计算这个值

def get_remaining(self, warehouse):"""剩余天数 = 保质期天数 - (当前日期 - 生产日期):param warehouse::return:"""return warehouse.quality_guarantee - (warehouse.date_of_manufacture - datetime.datetime.now(tz=pytz.UTC)).daysdef get_remaining_day(self, warehouse):"""保质期日期 = 生产日期+剩余天数"""return warehouse.date_of_manufacture + datetime.timedelta(days=warehouse.quality_guarantee)

同理再根据需求添加几个字段

• 总库存

• 出库

• 入库

• 已经出库时间

• 已经入库时间

total = serializers.SerializerMethodField(label="总库存", read_only=True, help_text="一个产品的总库存")
warehouse1 = serializers.SerializerMethodField(label="出库", read_only=True, help_text="一个产品的总出库")
warehouse2 = serializers.SerializerMethodField(label="入库", read_only=True, help_text="一个产品的总入库")
warehouse1_time = serializers.SerializerMethodField(label="已经出库时间", read_only=True, help_text="出库距离当前的时间")
warehouse2_time = serializers.SerializerMethodField(label="已经入库时间", read_only=True, help_text="入库距离当前的时间")

实现字段的计算

def get_total(self, warehouse):total = self.get_warehouse1(warehouse) - self.get_warehouse2(warehouse)return totaldef get_warehouse1(self, warehouse):product_id = warehouse.product_idwarehouse_info = Warehouse.objects.filter(stock_status=1).values("product").annotate(total=Sum("num")).all()total = warehouse_info.filter(product_id=product_id) and \warehouse_info.filter(product_id=product_id).get()["total"] or 0return totaldef get_warehouse2(self, warehouse):product_id = warehouse.product_idwarehouse_info = Warehouse.objects.filter(stock_status=2).values("product").annotate(total=Sum("num")).all()total = warehouse_info.filter(product_id=product_id) and \warehouse_info.filter(product_id=product_id).get()["total"] or 0return totaldef get_warehouse1_time(self, warehouse):warehouse2_time = warehouse.c_time - datetime.datetime.now(datetime.timezone(datetime.timedelta(hours=+8)))return warehouse2_time.daysdef get_warehouse2_time(self, warehouse):warehouse2_time = datetime.datetime.now(datetime.timezone(datetime.timedelta(hours=+8))) - warehouse.c_timereturn warehouse2_time.days

视图

from rest_framework.viewsets import ModelViewSetfrom utils.pagination import TenItemPerPagePagination
from warehouse.models import Warehouse
from warehouse.serializers import WarehouseModelSerializerclass WarehouseViewSet(ModelViewSet):queryset = Warehouse.objects.filter(is_delete=False).order_by("-c_time")serializer_class = WarehouseModelSerializerpagination_class = TenItemPerPagePaginationordering_fields = ['c_time']def perform_destroy(self, instance):instance.is_delete = Trueinstance.save()  # 逻辑删除

路由

backend/apps/warehouse/urls.py

from django.urls import path, include
from rest_framework.routers import DefaultRouter
from . import viewsrouter = DefaultRouter()
router.register("warehouse", views.WarehouseViewSet)urlpatterns = [path('', include(router.urls))
]

backend/LightSeeking/urls.py

urlpatterns = [...path('', include('warehouse.urls')),
]

代码

本次代码修改见：

https://gitee.com/zx660644/light-seeking/commit/2a5f9e4a26ff56e7cef5e6d4bdaf0adc63bb37b0

测试

先添加一个产品信息

访问http://127.0.0.1:8000/product/

填入产品信息后点击POST

再访问http://127.0.0.1:8000/warehouse/

添加一个库存信息

查看结果

{"id": 1,"product": {"id": 1,"c_time": "2022-09-02T12:14:32.356282+08:00","u_time": "2022-09-02T12:14:32.356417+08:00","is_delete": false,"product_id": "0001","category": "饮料","brand": "可口可乐","name": "可乐","price": "3.00","sample_png": "","desc": "无"},"remaining": 367,"remaining_day": "2023-09-01T12:15:00+08:00","total": 998,"warehouse1": 998,"warehouse2": 0,"warehouse1_time": -1,"warehouse2_time": 0,"c_time": "2022-09-02T12:15:46.366239+08:00","u_time": "2022-09-02T12:15:46.366352+08:00","price": "2.50","date_of_manufacture": "2022-09-01T12:15:00+08:00","quality_guarantee": 365,"num": 998,"stock_status": 1,"order_id": "","supplier": "测试供应商","desc": ""
}

其中product字段包含了我们入库的产品信息

另外之前序列化器中添加的几个字段也出现了

bug修复

不过从这里看出来，之前写了个bug，之前把日期计算写反了

def get_remaining(self, warehouse):"""剩余天数 = 保质期天数 - (当前日期 - 生产日期):param warehouse::return:"""return warehouse.quality_guarantee - (datetime.datetime.now(tz=pytz.UTC) - warehouse.date_of_manufacture).days

再次刷新后查看 remaining变为了364

{"data": {"page": 1,"pageSize": 20,"rows": [{"id": 1,"product": {"id": 1,"c_time": "2022-09-02T12:14:32.356282+08:00","u_time": "2022-09-02T12:14:32.356417+08:00","is_delete": false,"product_id": "0001","category": "饮料","brand": "可口可乐","name": "可乐","price": "3.00","sample_png": "","desc": "无"},"remaining": 364,"remaining_day": "2023-09-01T04:15:00Z","total": 998,"warehouse1": 998,"warehouse2": 0,"warehouse1_time": -1,"warehouse2_time": 0,"c_time": "2022-09-02T12:15:46.366239+08:00","u_time": "2022-09-02T12:15:46.366352+08:00","price": "2.50","date_of_manufacture": "2022-09-01T12:15:00+08:00","quality_guarantee": 365,"num": 998,"stock_status": 1,"order_id": "","supplier": "测试供应商","desc": ""}],"total": 1},"message": "","code": 200,"next": null,"previous": null
}