Django BoundField

一、BoundField

from django.forms.boundfield import  BoundField

BoundField是一个将字段添加数据的一个类，给对应的form字段封装上数据。

比如 ：我在我博客网站后台添加一篇文章的时候：

 Tags和Author都是有数据的，BoundField他将modelform中的字段和model中对应数据进行了封装。

二、BoundField的操作

1. 遍历modelform实例，得到

for boundfield in modelForm:
    print(boundfield)  # 得到每一个forms字段对应的HTML代码，并且封装了从数据库取出的数据
    print(type(boundfield)) # 每一个html片段都是一个BoundField对象
　　 
<input type="text" name="title" maxlength="32" required id="id_title" />
<input type="text" name="publishDate" required id="id_publishDate" />
<input type="number" name="price" step="0.01" required id="id_price" />

2. 获取Form字段，及字段类型

for boundfield in modelForm:
     print(boundfield.field)
     print(type(boundfield.field))

boundfield.field 
<django.forms.fields.CharField object at 0x0000017765B6D3C8>
<django.forms.fields.DateField object at 0x0000017765B6D438>
<django.forms.fields.DecimalField object at 0x0000017765B6D4A8>
<django.forms.models.ModelChoiceField object at 0x0000017765B6D518>
<django.forms.models.ModelMultipleChoiceField object at 0x0000017765B6D588>

boundfield.field类型
<class ''django.forms.fields.CharField''>
<class ''django.forms.fields.DateField''>
<class ''django.forms.fields.DecimalField''>
<class ''django.forms.models.ModelChoiceField''>
<class ''django.forms.models.ModelMultipleChoiceField''>

 3.拿取BoundField字段对象对应的数据

boundfield.field.queryset

django drf django-filter的method过滤

1.View Demo

from django.shortcuts import render

from rest_framework.views import APIView
from rest_framework.response import Response
from rest_framework import status
from rest_framework.parsers import JSONParser
from rest_framework import mixins, generics
from rest_framework.generics import ListAPIView
from rest_framework.pagination import PageNumberPagination
from goods.models import Goods, GoodsCategory
from goods.serializer import GoodsSerializer, CategorySerializer
from rest_framework import viewsets
from django_filters.rest_framework import DjangoFilterBackend

import django_filters
from rest_framework import filters
from django.db.models import Q


class GoodsFilter(django_filters.rest_framework.FilterSet):
    category_id = django_filters.rest_framework.NumberFilter(method=''filter_catetory_id'')

    def filter_catetory_id(self, queryset, name, value):
        return queryset.filter(Q(category_id=value) | Q(category__parent_category_id=value) | Q(
            category__parent_category__parent_category_id=value))

    class Meta:
        model = Goods
        fields = [''category_id'']


class GoodsList(mixins.ListModelMixin, viewsets.GenericViewSet):
    class GoodsPagination(PageNumberPagination):
        page_size = 2
        page_size_query_param = ''pageSize''
        page_query_param = ''p''
        max_page_size = 100

    queryset = Goods.objects.all()  # 不能切片后再过滤，例如：Goods.objects.all()[:10]
    serializer_class = GoodsSerializer
    pagination_class = GoodsPagination
    filter_backends = (DjangoFilterBackend, filters.SearchFilter, filters.OrderingFilter)
    search_fields = (''=name'',)  # 文档：https://www.django-rest-framework.org/api-guide/filtering/#searchfilter
    ordering_fields = (''name'',)
    # filter_fields = (''name'',) #逗号必加,缺点无法模糊查询
    filterset_class = GoodsFilter

2.SerializerDemo

class GoodsSerializer(serializers.ModelSerializer):
    """
    Goods的serializer
    """
    # 自定义，可以获取到外键数据
    # read_only表示只用在获取数据
    category_obj = CategorySerializer(source=''category'',read_only=True)
    category_name = serializers.CharField(source=''category.name'',read_only=True)
    class Meta:
        model = Goods
        # 外键写类里的名就可以
        # fields = (''name'',''chick_num'',''category'')
        fields = ''__all__''

3.test

django fileup-load

##文件上传

###使用form表单类的上传

forms.py

from django import forms

class UploadFileForm(forms.Form):
    title = forms.CharField(max_length=50)
    file = forms.FileField()

view处理这个form将会从request.FILES中接收file data，它是一个包含所有表单中FileField、ImageField和其他FileField的子类的字典，获取某个文件用request.FILES[''filename'']

注：上传文件的form表单必须是POST method,并且enctyoe="ultipart/form-data"。否则request.FILES将为空。

大多数情况下，您只需将文件数据从请求传递到表单，就像绑定上传文件到表单中所描述的那样。例如：

views.py
from django.http import HttpResponseRedirect
from django.shortcuts import render
from .forms import UploadFileForm

# Imaginary function to handle an uploaded file.
from somewhere import handle_uploaded_file

def upload_file(request):
    if request.method == ''POST'':
        form = UploadFileForm(request.POST, request.FILES)
        if form.is_valid():
            handle_uploaded_file(request.FILES[''file''])
            return HttpResponseRedirect(''/success/url/'')
    else:
        form = UploadFileForm()
    return render(request, ''upload.html'', {''form'': form})


# 上传文件
def handle_uploaded_file(f):
with open(''some/file/name.txt'', ''wb+'') as destination:
    for chunk in f.chunks():
        destination.write(chunk)

注：通过UploadedFile.chunks()进行循环而不是使用read()可以确保大文件不会淹没系统的内存。

##Handling uploaded files with a model

# models.py

from django.contrib.auth.models import AbstractUser


class UserInfo(AbstractUser):
	nid = models.AutoField(primary_key=True)
    telephone = models.CharField(max_length=11, null=True, unique=True)
    avatar = models.FileField(upload_to=''avatars/'', default="avatars/default.png")

# forms.py

from django.http import HttpResponseRedirect
from django.shortcuts import render
from .forms import ModelFormWithFileField

def upload_file(request):
    if request.method == ''POST'':
        form = ModelFormWithFileField(request.POST, request.FILES)
        if form.is_valid():
            # file is saved
            form.save()
            return HttpResponseRedirect(''/success/url/'')
    else:
        form = ModelFormWithFileField()
    return render(request, ''upload.html'', {''form'': form})

##多文件上传

forms.py
from django import forms

class FileFieldForm(forms.Form):
    file_field = forms.FileField(widget=forms.ClearableFileInput(attrs={''multiple'': True}))

重写FormView

# views.py

from django.views.generic.edit import FormView
from .forms import FileFieldForm

class FileFieldView(FormView):
    form_class = FileFieldForm
    template_name = ''upload.html''  # Replace with your template.
    success_url = ''...''  # Replace with your URL or reverse().

    def post(self, request, *args, **kwargs):
        form_class = self.get_form_class()
        form = self.get_form(form_class)
        files = request.FILES.getlist(''file_field'')
        if form.is_valid():
            for f in files:
                ...  # Do something with each file.
            return self.form_valid(form)
        else:
            return self.form_invalid(form)

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