djano一对一、多对多、分页实例代码

-filter
id=3
id__gt=3
id__lt=3
id__lte=3
id__gte=3

-in /not in
.filter(id__in=[]) in
.exclude(id__in=[]) not in

-between......and
.filter(id__range=[])

-like
.filter(name__startswith='XX') like 'XX%'
.filter(name_istartswith='XX') #忽略大小写
.filter(name__endswith='XX') like'%XX'
.filter(name__contains='XX') like'%XX%'
.filter(name_regax='^XX$') like'%XX%'精准匹配

-or
from django.db.models import Q
Q和|连用为or
&为and


-order by
models.UserInfo.objects.all().order_by('id')#升序#('-id')则为降序
#若有2个值，则第一个先排序，第二个后排序

-group by
from django.db.models import Sum,Count,Min,Max
models.UserInfo.objects.values('name').annota1te(xx=Sum('age'))
models.UserInfo.objects.values('name').annota1te(xx=Sum('age')).filter(XX__gt=50)#二次筛选

-count
models.UserInfo.objects.count()

-limit分页
models.UserInfo.objects.all()[X,XX]#利用切分来分页

-distinct
models.UserInfo.objects.values('XX').distinct()

-原生SQL
from django.db import connection

-first
-last两个返回的都是对象
​
-only
返回值为列表里面套对象

-defer
除了某一列以外的其他对象，返回值为列表套对象、

-F
拿到某一列的值，但是只能进行数组操作

id name age
1 zekai 18
2 lxxx 58

private:
id salary sp_id(外键+unique)
1 5000 1
2 4000 2

res = models.UserInfo.objects.filter(name='zekai').first()


print(res.private.salary)


#res.子表表名小写.子表字段名

res= models.Private.objects.filter(salary=5000).first()
print(res.sp.name,res.sp.age)
#res.关联的字段名.母表字段名

boy:
id name
1 laowang
2 XXX

girl:
id name
1 正正
2 连连
3 爱爱
4 凤姐
5 乔碧萝

boy2girl
id bid gid
1 1 1
2 1 2 
3 1 3
4 2 2
5 2 4
6 2 5

models.py:
class Boy(models.Model):
bname=models.CharField(max_length=32,null=True)
​
class Girl(models.Model):
gname=models.CharField(max_length=32,null=True)
​
class Boy2Girl(models.Model):
b = models.ForeignKey("Boy",null=True)
g = models.ForeignKey("Girl",null=True)
​
​
#联合唯一索引
class Meta:
unique_together=[
('b','g')
]


views.py:
def test1(rsquest):
boyinfo= [
models.Boy(bname='雷俊'),
models.Boy(bname='雷鸣'),
models.Boy(bname='雷公'),
models.Boy(bname='雷军'),
models.Boy(bname='雷峰'),
​
]
​
girlinfo=[
models.Girl(gname='真真'),
models.Girl(gname='天天'),
models.Girl(gname='爱爱'),
models.Girl(gname='凤姐'),
models.Girl(gname='乔碧萝'),
​
]
models.Girl.objects.bulk_create(boyinfo)
​
b2ginfo=[
models.Boy2Girl(b_id=1,g_id=1),
models.Boy2Girl(b_id=2, g_id=4),
models.Boy2Girl(b_id=3, g_id=3),
models.Boy2Girl(b_id=4, g_id=5),
models.Boy2Girl(b_id=5, g_id=2),
models.Boy2Girl(b_id=3, g_id=5),
models.Boy2Girl(b_id=5, g_id=4),
]
​
​
​
return HttpResponse('ok')
查询：需求，查找和雷俊约会的姑娘
res = models.Boy2Girl.objects.filter(bname='雷俊').first()
love_list = res.boy2girl_set.all()
for love in love_list:
print(love.g.name)
​

res = models.Boy2Girl.objects.filter(b__bname='雷俊') #[obj,obj...]
for love in res:
print(res.g.name)

res = models.Boy2Girl.objects.filter(b__bname='雷俊').values('g__gname')
print(res) # [{},{}...]
​

from django.core.paginator import Paginator
  #per_page:每页显示条目数量
  #count：数据总个数
  #num_pages：总页数
  #page_range：总页数的索引范围
  #page：page对象
  paginator = Paginator(userlist,10)
  
  #has_next:是否有下一页
  #next_page_number:下一页页码
  #has_previous:是否有上一页
  #previous_page_number:上一页页码
  #object_list:分页之后的数据列表
  #number:当前页
  #paginator：paginator对象
  sers = paginator.page(cur_page)
  
  return render(request,'index.html',{"users":users})
​
-自定制分页

class PageInfo():
  def __init__(self, cur_page, total, per_page=10, show_page=11):
    self.cur_page = cur_page
    self.per_page = per_page
    self.total = total
    self.show_page = show_page
​
    a, b = divmod(self.total, self.per_page)
    if b:
      a = a + 1
    self.total_page = a  #### 总页数
​
  #### 获取起始索引
  def get_start(self):
    start = (self.cur_page - 1) * self.per_page
    return start
  #### 获取结束索引
  def get_end(self):
    return self.cur_page * self.per_page
​
  def get_page(self):
​
    half = (self.show_page - 1) // 2
​
    #### taotal_page = 5 < show_page = 11
    if self.total_page < self.show_page:
      begin = 1
      end = self.total_page
    else:
      #### 左边极值判断
      if self.cur_page - half <= 0 :
        begin = 1
        # end = self.cur_page + half
        end = self.show_page
      #### 右边极值的判断
      elif self.cur_page + half > self.total_page:
        # begin = self.cur_page - half
        begin = self.total_page - self.show_page + 1
        end = self.total_page  ### 31
      #### 正常页码判断
      else:
        begin = self.cur_page - half
        end = self.cur_page + half
​
    page_list = []
    if self.cur_page == 1:
      astr = "<li><a href='#' aria-label='Previous'><span aria-hidden='true'>&laquo;</span></a></li>"
    else:
      astr = "<li><a href='/custom/?cur_page=%s' aria-label='Previous'><span aria-hidden='true'>&laquo;</span></a></li>" % (self.cur_page-1)
    page_list.append(astr)
​
    for i in range(begin, end + 1):
      if self.cur_page == i:
        # astr = "<a style='display:inline-block; padding:5px;margin:5px;background-color:red;' href='/custom/?cur_page=%s'>%s</a>" % (i, i)
        astr = "<li class='active'><a href='/custom/?cur_page=%s'>%s</a></li>" % (i, i)
      else:
        # astr = "<a style='display:inline-block; padding:5px;margin:5px' href='/custom/?cur_page=%s'>%s</a>" % (i, i)
        astr = "<li><a href='/custom/?cur_page=%s'>%s</a></li>" % (i, i)
      page_list.append(astr)
​
    if self.cur_page == self.total_page:
      astr = "<li><a href='#' aria-label='Next'><span aria-hidden='true'>&raquo;</span></a></li>"
    else:
      astr = "<li><a href='/custom/?cur_page=%s' aria-label='Next'><span aria-hidden='true'>&raquo;</span></a></li>" % (self.cur_page+1)
    page_list.append(astr)
​
    s = " ".join(page_list)
​
    return s
​
def custom(request):
​
  cur_page = request.GET.get('cur_page')
  cur_page = int(cur_page)
​
  '''
  mysql:
    seelct * from userinfo limit 0, 10 
    seelct * from userinfo limit 10, 10 
    
    cur_page  start  show_page
     1     0   10
     2     10  10
     3     20  10
     n     (n-1)*10, 10
  limit (cur_page - 1) * show_page 
  '''
  # total = models.UserInfo.objects.count()
  total = models.UserInfo.objects.filter(id__lte=44).count()
  page = PageInfo(cur_page, total)
  start = page.get_start()
  end = page.get_end()
​
  ### cur_page = 1  start = 0  end = 10
  ### cur_page = 2  start = 10 end = 20
  ### cur_page = 3  start =20 end = 30
  # user_list = models.UserInfo.objects.all()[start:end]
  user_list = models.UserInfo.objects.filter(id__lte=44)[start:end]
​
​
  return render(request, "custom.html", {"user_list":user_list, "page":page})