CRM手记- 12 | Django

Posted 2020-10-22 胡说八道

# 4.删除
# 在修改记录页面左下角添加一个删除按钮,一个链接,跳转至一个提示删除内容的页面,确认删除；
#     关联删除,删除记录同时也删除外键的关联表;
    # table_obj_common.html
       <div class="form-group">
            <div class="col-sm-10">
                <a href="{% table_obj_delete app_name model_name form_obj.instance.id %}">DELETE</a>
            </div>
        </div>
    # urls.py
        url(r‘^(\w+)/(\w+)/(\d+)/add/$‘, views.table_obj_delete, name="table_obj_delete"),
    # views.py
        @login_required
        def table_obj_delete(app_name,model_name,obj_id):
            """删除记录"""
            admin_class = site.enabled_admins[app_name][model_name]
            obj = admin_class.model.objects.get(id=obj_id)
            return render(request, ‘kingadmin/table_obj_delete.html‘,locals())
    # table_obj_delete.html
        delete {{ obj }}
        <!-- obj代表当前这条记录 -->

# 在删除页面确认,后台删除该记录;
#     >> a = models.CustomerInfo.objects.first()
#     >> a.delete()  # 会不会删除关联的表数据?会;|跟踪记录表;
# django-admin在删除时显示友好提示,列出所有关联表;

# 一层层递归所有外键,删除;
    # table_obj_delete.html
        {% display_all_related_objs obj as all_related_obj_eles%}
        {{ all_related_obj_eles|safe }}
    # kingadmin_tag.py
        @register.simple_tag
        def display_all_related_objs(obj):
            """显示要被删除对象的所有关联对象"""
            ele = "<ul>"
            ele += "<li>%s</i>"%obj
            # 1.forignkey | get_internal_type()
            for reversed_fk_obj in obj._meta.related_objects:
                related_table_name = reversed_fk_obj.name
                related_lookup_key = "%s_set"%related_table_name
                # >> getattr(a,‘customerinfo_set‘) # 获取关联表
                # >> getattr(a,‘customerinfo_set‘).all() # 关联表所有对象
                related_objs = getattr(obj,related_lookup_key).all() # 反向查所有关联数据
                ele += "<li>%s</li><ul>"%related_table_name
                # 如果是many_to_many就不需要深入递归,打印影响的数据
                if reversed_fk_obj.get_internal_type() == "ManyToManyField":
                    for i in related_objs:
                        ele += "<li><a href=‘/kingadmin/%s/%s/%s/change/‘>%s</a> 记录中与%s相关数据将被删除</li>" % (i._meta.app_label,i._meta.model_name,i.id,i, obj) # 课程相关
                else:        
                    for i in related_objs:
                        ele += "<li>%s</li>" % i
                        ele += display_all_related_objs(i) # 调用自己,递归查找
                    
                ele += "<ul></li>"
            ele += "</ul>"
            return ele
                    
    # >> a._meta.fields  # 获取所有字段
    # >> a._meta.fields_map # 外链的表映射
    # (‘student‘:<ManyToOneRel:crm.student>,...)
    # >> from crm import models
    # >> a = models.CustomerInfo.objects.all()[1]
    # >> a
    # <CustomerInfo: ‘大西瓜‘> # 学员表中的学生是外键关联着客户表的;一对多反向查询(外键设置在student);
    # >> a.student_set.select_related() # 获取当前查询对象的所有外键字段对应表的查询集：student
    # <QuerySet [<Student:‘大西瓜‘ >]>
    
    # 只要a._meta.fields_map遇到ManyToOneRel的,就反向去查找：
    
    # 要考虑自关联,referer_from 转介绍
    # >> a._meta.fields_map
    # (...‘customerinfo‘:<ManyToOneRel:crm.student>...) # 映射中含有当前的表,忽略;
    
    # 综合：
    # //////a._meta.fields可以获得所有foreignkey # 不需要管,学生删除不影响客户表;
    # a._meta.related_obj 可以获取所有反向关联;而不使用a._meta.fields_map,因为有个脏数据需要判断;
    # a._meta.many_to_many可以获取多对多关系的数据;
        
    # 多层级递归删除
        # 课程-班级-上课记录-学习记录；
        # 课程被删除,与之多对多关系的客户信息不会被删除,但是字段会收到影响;
        
    # 给展示记录添加链接跳转查看
    ele += "<li><a href=‘/kingadmin/%s/%s/%s/change/‘>%s</a> 记录中与%s相关数据将被删除</li>" % (app_name,model_name,i.id,i, obj)
    {% display_all_related_objs i._meta.app_label,i._meta.model_name,i.id,i, obj as all_related_obj_eles%}
    
    # table_obj_delete.html | 点击删除所有关联数据
        <form method=‘post‘>
            {% csrf_token %}
            <input type=‘submit‘ class=‘btn btn-danger‘ value=‘确认删除‘>
            <a>返回</a>
        </form>
    # views.py
        @login_required
        def table_obj_delete(app_name,model_name,obj_id):
            """删除记录"""
            admin_class = site.enabled_admins[app_name][model_name]
            obj = admin_class.model.objects.get(id=obj_id)
            if request.method == ‘POST‘:
                obj.delete()
                return redirect(‘/kingadmin/{app_name}/{model_name}/‘.format(app_name=app_name,model_name=model_name))
            return render(request, ‘kingadmin/table_obj_delete.html‘,locals())