django笔记(3)-数据库操作

一:路由系统
    url
    1.url(r'^index/', views.index),url(r'^home/',views.Home.as_view()), 一个url对应一个函数或一个类
    2.url(r'^detail-(d+).html',views.detail), 一类url对应一个函数或一个类 动态url
    3.url(r'^detail-(?P<nid>d+)-(?P<uid>d+).html',views.detail), 正则表达式 第一数字匹配赋值给nid 在函数里面就不用考虑顺序 比较常用 动态url

        ps: def detail(request,*args,**kwargs):
                pass
    实战:
            1.
            url(r'^detail-(d+)-(d+).html',views.detail)
            def func(request,nid,uid):
                pass

            def func(request,*args):
                args=(2,6)
                pass

            2.
            url(r'^detail-(?P<nid>d+)-(?P<uid>d+).html',views.detail)
            def func(request,nid,uid):
                pass

            def func(request,**kwargs):
                kwargs={'nid':1,'uid':3}


    4.name:方便提交表单
    URL路由关系进行命名,以后可以根据此名称自动生成自己想要的URL
    url(r'^index999999999/', views.index,name='indexx'),
    def func(request,*args,**kwargs):
        from django.urls import reverse
        reverse('indexx')  #生成index999999999

    url(r'^index999999999/(d+)/(d+)/', views.index,name='indexx'),
    def func(request,*args,**kwargs):
        from django.urls import reverse
        reverse('indexx',args=(1,6)) #生成index999999999/1/6

    url(r'^index999999999/(?P<nid>d+)/(?P<uid>d+)/', views.index,name='indexx'),
     def func(request,*args,**kwargs):
        from django.urls import reverse
        reverse('indexx',kwargs=('nid':11,'uid':66)) #生成index999999999/11/66

   xxxx.html
    {% url "indexx" %}       #对应index999999999
    {% url "indexx" 1 6 %}   #对应index999999999/1/6
    {% url "indexx" nid=11 uid=66 %}  #对应index999999999/11/66


    模板语言里面:
        {% url 'indexxx' %}
        {% url 'indexxx' 8 6  %}


        注:{{ request.path_info }} 当前页面url



     5.



二:视图
    request.POST
    request.GET
    request.FILES

    #获取checkbox等多选内容
    request.POST.getlist()

    #上传文件,form标签做特殊设置enctype="multipart/form-data"
    obj=request.FILES.get('fafafa')
    obj.name
    f=open(obj.name,mod='wb')
    for item in obj.chunks():
        f.write(item)
    f.close()


    FBV  function base view
    url.py
    index -->函数名
    view.py
       def 函数(request):
           ...

    CBV  class base view  执行类里面的指定的方法
    /index/  -->类
    建议两者都用


三:模板


四:orm操作
    select * from tb where id>1
    #对应关系
    models.tb.objects.filter(id__gt=1)
    models.tb.objects.filter(id=1)
    model.tb.objects.filter(id__lt=1)

    a.创建类(代码)
    from django.db import models
class UserInfo(models.Model):
    # id列,自增,主键
    # 用户名列,字符串类型,指定长度
    username=models.CharField(max_length=32)
    password=models.CharField(max_length=64)

   b.注册app:
    settings.py:
            INSTALLED_APPS =[
            '''
            'app01',
            ]

    c.执行命令:
    python manage.py makemigrations  生成migrations下的文件
    python manage.py migrate         根据生成的文件创建表和数据库

    d.连接mysql
    django默认使用MySQLdb模块连接mysql,但目前py3.x没有这个模块
    修改为pymsql
    project下的__init__.py
    import pymysql
    pymysql.install_as_MySQLdb()

    : base.py将36行注释
        if version < (1, 3, 13):
            raise ImproperlyConfigured('mysqlclient 1.3.13 or newer is required; you have %s.' % Database.__version__)



        File "C:Python37libsite-packagesdjangodbackendsmysqloperations.py", line 146, in last_executed_query

    query = query.decode(errors='replace')

  AttributeError: 'str' object has no attribute 'decode'

  解决办法:打开此文件把146行的decode修改为encode
    如果已经有migrations文件就直接执行 python manage.py migrate 创建表


        1.根据类(代码)自动创建数据库表
        app下的model.py

        字段:字符串
             数字
             时间
             二进制
             自增(primary_key=True)

        参数:
            null                数据库中字段是否可以为空 null=True
            db_column           数据库中字段的列名  db_column='xx'
            default             数据库中字段的默认值 default='xx'
            primary_key         数据库中字段是否为主键  primary_key=True
            db_index            数据库中字段是否可以建立索引 db_index=True
            unique              数据库中字段是否可以建立唯一索引 unique=True
            unique_for_date     数据库中字段【日期】部分是否可以建立唯一索引  unique_for_date=True
            unique_for_month    数据库中字段【月】部分是否可以建立唯一索引  unique_for_month=True
            unique_for_year     数据库中字段【年】部分是否可以建立唯一索引  unique_for_year=True

            auto_now_add        创建时 自动生成创建时间 auto_now_add=True

            auto_now            更新时 自动生成更改时间 auto_now=True
                                obj=models.UserGroup.objects.filter(uid='1').first() 更新uptime用这种方法
                                obj.caption="DBA"
                                obj.save()

            verbose_name        django  admin中显示的字段名称  verbose_name="姓名"
            blank               django  admin中是否允许用户输入为空  blank=True
            editable            django  admin中是否可以编辑  editable=False
            help_text           django admin中该字段的提示信息 help_text="邮件"

            choices             django admin中显示选择框的内容,用不变动的数据放在内存中从而避免跨表操作
                                :user_type_choice=(
                                                (1,'super user'),
                                                 (2,'normal user'),
                                                (3,'normal normal user'),
                                                 )
                                 user_type_id=models.IntegerField(choices=user_type_choice,default=1)

            error_messages      自定义错误信息(字典类型),从而定制想要显示的错误信息;
                                字典健:null, blank, invalid, invalid_choice, unique, and unique_for_date
                                如:{'null': "不能为空.", 'invalid': '格式错误'}

            validators          自定义错误验证(列表类型),从而定制想要的验证规则

        2.根据类(代码)对数据库表中的数据进行各种操作
               一对多:
                    a.外键
                    b.外键字段_id
                    c.外键id创建数据 models.tb.object.create(name='root',user_group_id=1)

                    d.
                        user_list=models.tb.object.all()
                        for row in user_list:
                            row.id
                            row.user_group_id
                            row.user_group.caption 跨表操作


    数据库配置
    DATABASES = {
    'default': {
    'ENGINE': 'django.db.backends.mysql',
    'NAME':'dbname',
    'USER': 'root',
    'PASSWORD': 'xxx',
    'HOST': '',
    'PORT': '',
    }
}

https://www.cnblogs.com/wupeiqi/articles/5237704.html


创建外键
    models.ForeignKey("关联的外表",to_field='外表的主键')
    class UserType(models.Model):
        caption=modules.CharField(max_length=32)
        id   caption
        1  普通用户
        2.VIP用户
        3.游客

    class User(models.Model):
        age=models.IntergerField()
        name=models.CharField(max_length=10)
        user_type=models.ForeignKey('UserType',to_field='id')

        name  age  user_type_id
        mark   19    1
        gasol  31    2
        lebrom  29   3

原文地址:https://www.cnblogs.com/leiwenbin627/p/11005941.html