ORM基本操作

1、创建单表模型类

class Goods(models.Model):
    goods_name = models.CharField(max_length=32)
    goods_price = models.DecimalField(max_digits=9,decimal_places=2)
    goods_num = models.IntegerField()

    class Meta:
        db_table = 'tb_goods'

2、ＯＲＭ基本操作

   class ORMView(APIView):
    def get(self,request):
        # 单一查询，如果结果不存在报错
        goodsobj = Goods.objects.get(goods_price=6.66)
        obj = GoodsSerializers(goodsobj)
        return Response(obj.data)
   
   # # 查询不包含id=3的数据
    # goodsobj = Goods.objects.exclude(id=3)
    # obj = GoodsSerializers(goodsobj, many=True)
    # return Response(obj.data)
        # # 查询结果的数量
# goodsobj = Goods.objects.all().count()
# return Response(goodsobj)

 # #   聚合函数　　使用aggregate()过滤器调用聚合函数。聚合函数包括：Avg 平均，Count 数量，Max 最大，Min 最小，Sum 求和
     # goodsobj = Goods.objects.aggregate(Sum('goods_num'))
    # print(goodsobj)
    # # obj = GoodsSerializers(goodsobj, many=True)
    # return Response({'data':''})
  # #   比较查询　　字段名__lt：小于    字段名__lte：小于等于
    # goodsobj = Goods.objects.filter(id__lt=4)
    # obj = GoodsSerializers(goodsobj, many=True)
    # return Response(obj.data)
 # #   比较查询　　字段名__gt：大于    字段名__gte：大于等于
    # goodsobj = Goods.objects.filter(id__gte=2)
    # obj = GoodsSerializers(goodsobj, many=True)
    # return Response(obj.data)

  # #  　空查询　　字段名__isnull
# goodsobj = Goods.objects.filter(goods_name__isnull=False)
# obj = GoodsSerializers(goodsobj, many=True)
# return Response(obj.data)

 # #   模糊查询　字段名__endswith　以　莓　结尾的数据
    # goodsobj = Goods.objects.filter(goods_name__endswith='莓')
    # obj = GoodsSerializers(goodsobj, many=True)
    # return Response(obj.data)
      # #   模糊查询　字段名__tartswith　以　苹　开头的数据    
　　# goodsobj = Goods.objects.filter(goods_name__startswith='苹')    
　　# obj = GoodsSerializers(goodsobj,many=True)    
　　# return Response(obj.data)​   
　　# #   模糊查询　字段名__contains　包含　果　的的数据    
　　# goodsobj = Goods.objects.filter(goods_name__contains='果')    
　　# obj = GoodsSerializers(goodsobj,many=True)    
　　# return Response(obj.data)

  # # 范围查询:  in  只查询列表中的具体值
    # goodsobj = Goods.objects.filter(goods_price__in=[12,25,6.66]).all()
    # obj = GoodsSerializers(goodsobj,many=True)
    # return Response(obj.data)

    # # 范围查询:  range １～２０之间
    # goodsobj = Goods.objects.filter(goods_price__range=[1,20]).all()
    # obj = GoodsSerializers(goodsobj,many=True)
    # return Response(obj.data)

  #    排序查询：  order_by 降序只需在字段名前加上 “ - ”
        goodsobj = Goods.objects.all().order_by('-goods_num')
        obj = GoodsSerializers(goodsobj, many=True)
        return Response(obj.data)

        #    F方法：比较两个字段对象之间的关系用F对象，F方法可以进行简单运算　
        #    查询价格　大于等于　库存的对象
        goodsobj = Goods.objects.filter(goods_price__gte=F('goods_num'))
        obj = GoodsSerializers(goodsobj, many=True)
        return Response(obj.data)
        
        #    Q方法：对对象进行复杂查询，并支持&（and）,|（or），~（not）操作符
        #    查询价格大于等于15的数据　或库存大于等于10的数据
        goodsobj = Goods.objects.filter(Q(goods_price__gte=15) | Q(goods_num__gte=10))
        obj = GoodsSerializers(goodsobj, many=True)
        return Response(obj.data)

3、创建一对多、多对多模型类

# 电影
class Movie(models.Model):
    movie_name = models.CharField(max_length=32)
    class Meta:
        db_table = 'tb_movie'


# 角色
class Role(models.Model):
    role_name = models.CharField(max_length=32)
    role_price = models.DecimalField(max_digits=9, decimal_places=2)
    role_desc = models.CharField(max_length=32)

    class Meta:
        db_table = 'tb_role'


# 演员
class Actor(models.Model):
    name = models.CharField(max_length=32)
    address = models.CharField(max_length=32, null=True, blank=True)
    age = models.IntegerField(null=True,blank=True)
    phone = models.CharField(max_length=32, null=True, blank=True)
    movie = models.ForeignKey(Movie, on_delete=models.CASCADE)
    role = models.ManyToManyField(Role)

    class Meta:
        db_table = 'tb_actor'

• 一对多正、反查找

   # #   正向查找　　对象．模型名．字段
    # actorobj = Actor.objects.get(id=1)
    # movieo = actorobj.movie.movie_name
    # print(movieo)
    # return Response('ok')

    #   反向查找  对象．模型名_set
    # movieobj = Movie.objects.get(id=1)
    # actorobj = movieobj.actor_set.all()
    # obj = ActorSerializers(actorobj,many=True)
    # print(obj.data)
    # return Response(obj.data)

4、多对多表操作

class ORMview2(APIView):
    def post(self,request):
        # # 多对多添加
        # # 方法一：在建立manytomany的models里添加数据，（一条，一个对象）
        # actor = Actor.objects.get(id=5)
        # role = Role.objects.get(id=5)
        #
        # data = actor.role.add(role)
        # print(data)
        # return Response('ok')


# 方法二：在未建立manytomany的models里添加数据，（一条，一个对象）
    actor = Actor.objects.filter(name='张译')
    role = Role.objects.get(id=5)

    data = role.actor_set.add(*actor)
    print(data)
    return Response('ok2')

5、父子组件的调用

import导入子组件
components注册子组件
注册的子组件当作标签来使用

• 子组件

<template>​  <div>​      <p>今天心情真美丽</p>   </div>​</template>

• 父组件

  <template>
  <div>
   <zi></zi>     <!-- 子组件当标签使用-->
  
   </div>
  
  </template>
  
  <script>
  
  import zi from "./zi";     //导入子组件
  
  export default {
  
   data() {
     return { 
  
      };
  
     },
  //注册子组件
     components: {     
  
      zi
  
     },
  
  }
  </script>
  

• 父组件给子组件传参

  父组件里的子标签里写上要传递的数据（:子组件的参数名字=父组件的参数名字）
  在子组件里注册参数（props）
  使用父组件传过来的参数

<template>
  <div>
    <zi :str='str'></zi><br>      
    <br>
    <button @click="change_zi()">修改子组件</button>
  </div>
</template>

<script>
import zi from "./zi";
export default {
  data() {
    return {
        str:'',
     
    };
  },

  components: {
    zi
  },

  methods:{
      change_zi(){
          this.str='今天的你真可爱！'
      },
  }
};
</script>

//子组件获取
<template>
  <div>
      <p>今天心情真美丽</p>
      {{str}}
  </div>
</template>

<script>
export default {
    props:['str'],
    data(){
        return{

        }

    },
  }
</script>

• 子组件给父组件传参

  子组件里先用特定的方法来把这个数据传递给父组件（this.$emit(‘方法的名字’,要传递的数据)）
  父组件的子标签里来接收数据(@子组件的方法=父组件的方法)
  methods里接收传过来的val并赋值

<template>
  <div>
      <p>今天心情真美丽</p>
      <button @click="change">修改父组件</button>
  </div>
</template>

<script>
export default {
    data(){
        return{

        }

    },
    methods:{
        change(){
            this.$emit('change_fu','真好！nice!')
        }
        
    }

}
</script>


//父组件获取
<template>
  <div>
    <zi @change_fu=get_zi></zi><br>
    {{data}}
  </div>
</template>

<script>
import zi from "./zi";
export default {
  data() {
    return {
        data:''
    };
  },

  components: {
    zi
  },

  methods:{
      get_zi(val){
          this.data=val
      }
  }
};
</script>