商城项目---day06---存储后端与模板渲染

我就是我 2022-12-05 01:37 6阅读 0赞

一：自定义django存储后端：  
1：问题：前端需要一个完整的图片路径，但是服务器存储的图片只是后面的部分链接，django如何拼接才能返回给前端一个完整的页面呢？

答：  
ImageField.url属性返回值到底是谁决定的(由**Django的存储后端的url()函数决定的**)；2、改写url()返回值，拼接出完整的图片链接；  
![在这里插入图片描述][watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L3FxXzQxMzQxNzU3_size_16_color_FFFFFF_t_70_pic_center]  
一句话总结：**`ImageField.url`的结果就是Django文件存储后端`url()`函数返回的结果！那么，我们只需要自定义一个文件存储后端，并改写`url()`函数返回完整图片链接就好了**

2：新建`meiduo_mall/utils/fastdfs.py`文件，自定义文件存储后端

from django.core.files.storage import Storage
    from django.conf import settings
    
    
    # 1:自定义的文件存储后端要继承django默认的存储后端Storage
    class FastDFSStorage(Storage):
    
        def _open(self, name, mode="rb" ):
            # 打开django本地文件
            pass
    
        def _save(self, name, content, max_length=None):
            # 上传图片
            pass
    
        def url(self, name):
            # 返回"http://image.meiduo.site:8888/" + 图片在数据库中存储的地址
            return settings.FDFS_BASE_URL + name

3：修改dev.py配置文件：**DEFAULT\_FILE\_STORAG：原因是让django知道用自己定义的存储后端而不是django自己的。另外为了方便以后修改路径，所以需要在配置文件增加系统环境变量FDFS\_BASE\_URL。**

# 自定义文件存储类：
    # 指定自定义的Django文件存储类
    DEFAULT_FILE_STORAGE = 'meiduo_mall.utils.fastdfs.FastDFSStorage'
    # 定义fdfs服务url前缀
    FDFS_BASE_URL = 'http://image.meiduo.site:8888/'

4：通过交互终端测试代码，获取完整的图片链接

(django_env) python@ubuntu:~/Desktop/meimei_project$ cd meiduo_mall/
    (django_env) python@ubuntu:~/Desktop/meimei_project/meiduo_mall$ python manage.py shell
    Python 3.5.2 (default, Nov 12 2018, 13:43:14) 
    [GCC 5.4.0 20160609] on linux
    Type "help", "copyright", "credits" or "license" for more information.
    (InteractiveConsole)
    >>> from apps.goods.models import *
    >>> im = SKUImage.objects.all()[0]
    >>> im
    <SKUImage: Apple MacBook Pro 13.3英寸笔记本 银色 4>
    >>> im.image.url
    'http://image.meiduo.site:8888/group1/M00/00/02/CtM3BVrPB4GAWkTlAAGuN6wB9fU4220429'

二：页面静态化理论：  
1：什么是页面静态化？？  
![在这里插入图片描述][watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L3FxXzQxMzQxNzU3_size_16_color_FFFFFF_t_70_pic_center 1]  
2：页面静态化解决的问题：  
网站首页(index.html)的访问频次是非常之高的，如果采用动态渲染的方式，每一次浏览器都需要请求动态服务器获取数据，然后渲染，那么咱们的动态服务器负载就会非常之高！

3：解决方案：  
![在这里插入图片描述][watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L3FxXzQxMzQxNzU3_size_16_color_FFFFFF_t_70_pic_center 2]

三：模板渲染的demo测试：  
1:新建`apps/contents/crons.py`文件，在该文件中写一个示例函数，来讲解如何使用django的接口进行页面渲染(模版+动态数据)

from django.template import loader
    
    from apps.goods.models import SKUImage
    
    
    def static_demo():
    
        # 1:使用get_templatehan函数获取模板页面对象
        template = loader.get_template("demo.html")
    
        # 2: 构造动态数据
    
        content = {
        
            'name': "任善文",
            'age': 18,
            'like': ['足球', '篮球', '乒乓球'],
            'sku_image': SKUImage.objects.get(pk=4),
        }
    
        # 3:使用模板页面对象的render函数来渲染页面
        page = template.render(content)
    
        # 4:将渲染后的页面重新写入静态服务器
        with open("demo.html",'w') as f:
            f.write(page)

2:创建模版文件\`meiduo\_mall/meiduo\_mall/templates/demo.html

<!DOCTYPE html>
    <html lang="en">
    <head>
        <meta charset="UTF-8">
        <title>Title</title>
    </head>
    <body>
    
    {
        {
         name }}
    {
        {
         age }}
    
    {
        % for l in like %}
        <li>{
        {
         l }}</li>
    {
        % endfor %}
    
    <img src="{
        { sku_image.image.url }}">
    
    </body>
    </html>

3:进入django调试交互模式调用函数渲染demo.html静态文件

>>> from apps.contents.crons import *
    >>> static_demo()

4:打开生成的页面：

<!DOCTYPE html>
    <html lang="en">
    <head>
        <meta charset="UTF-8">
        <title>Title</title>
    </head>
    <body>
    
    任善文
    18
    
    
        <li>足球</li>
    
        <li>篮球</li>
    
        <li>乒乓球</li>
    
    
    <img src="http://image.meiduo.site:8888/group1/M00/00/02/CtM3BVrPB4GAWkTlAAGuN6wB9fU4220429">
    
    </body>
    </html>

四：渲染美多商城首页静态页面：  
1：把老师给的`静态模版文件`文件夹里面的首页模版文件`index.html`放入工程`templates`模版目录中。  
2：编辑`apps/contents/crons.py`文件，定义`generate_static_index_html`函数实现渲染首页静态文件。

def generate_static_index_html():
    
        # 获取分类频道
        categories = get_categories()
    
        # 1:构建首页模板文件对象
        template = loader.get_template("index.html")
    
        # 2:构造动态数据
        content = {
        
            "categories": categories,
            "contents": None,
        }
    
        # 3:渲染完整的页面数据
        page = template.render(content)
    
        # 4:写入静态web服务器
        with open("/home/python/Desktop/meimei_project/front_end_pc/front_end_pc/index.html","w") as f:
            f.write(page)

3：进入django调试交互终端调用`generate_static_index_html`来渲染出首页静态文件。  
**注意：必须再次重新进入终端：因为距离上次打开终端时，我们还没有写这些代码，终端不会导入新的内容，所以必须重启终端。**

(django_env) python@ubuntu:~/Desktop/meimei_project/meiduo_mall$ python manage.py shell
    Python 3.5.2 (default, Nov 12 2018, 13:43:14) 
    [GCC 5.4.0 20160609] on linux
    Type "help", "copyright", "credits" or "license" for more information.
    (InteractiveConsole)
    
    >>> from apps.contents.crons import *
    >>> generate_static_index_html()

4：重启静态服务器演示:  
![在这里插入图片描述][watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L3FxXzQxMzQxNzU3_size_16_color_FFFFFF_t_70_pic_center 3]  
5:注意：get\_categories()函数今天没有实现，明天才实现，今天先借用。

def get_categories():
        # 模版参数categories是首页分类频道
        categories = {
        }
    
        # 获取首页所有的分类频道数据
        channels = GoodsChannel.objects.order_by(
            'group_id',
            'sequence'
        )
        # 遍历所有是分类频道，构建以组号作为key的键值对
        for channel in channels:
            # channel: GoodsChannel对象
            if channel.group_id not in categories:
                categories[channel.group_id] = {
        
                    'channels': [],  # 当前分组中的分类频道(一级分类)
                    'sub_cats': []  # 二级分类
                }
            # (1)、填充当前组中的一级分类
            cat1 = channel.category
            categories[channel.group_id]['channels'].append({
        
                'id': cat1.id,
                'name': cat1.name,
                'url': channel.url
            })
    
            # (2)、填充当前组中的二级分类
            cat2s = GoodsCategory.objects.filter(parent=cat1)
            for cat2 in cat2s:
                # cat2：二级分类对象
    
                cat3_list = []  # 每一次遍历到一个二级分类对象的时候，初始化一个空列表，用来构建三级分类
                cat3s = GoodsCategory.objects.filter(parent=cat2)
                # (3)、填充当前组中的三级分类
                for cat3 in cat3s:
                    # cat3；三级分类对象
                    cat3_list.append({
        
                        'id': cat3.id,
                        'name': cat3.name
                    })
    
                categories[channel.group_id]['sub_cats'].append({
        
                    'id': cat2.id,
                    'name': cat2.name,
                    'sub_cats': cat3_list  # 三级分类
                })
    
        return categories

## 一：首页广告模型类： ##

1：创建应用contents  
2：定义首页广告模型类  
apps.contents.models.py

from django.db import models
    
    from shopping_mall.utils.models import BaseModel
    
    
    class ContentCategory(BaseModel):
        """广告内容类别"""
        name = models.CharField(max_length=50, verbose_name='名称')
        key = models.CharField(max_length=50, verbose_name='类别键名')
    
        class Meta:
            db_table = 'tb_content_category'
    
        def __str__(self):
            return self.name
    
    
    class Content(BaseModel):
        """广告内容"""
        category = models.ForeignKey(ContentCategory, on_delete=models.PROTECT, verbose_name='类别')
        title = models.CharField(max_length=100, verbose_name='标题')
        url = models.CharField(max_length=300, verbose_name='内容链接')
        image = models.ImageField(null=True, blank=True, verbose_name='图片')
        text = models.TextField(null=True, blank=True, verbose_name='内容')
        sequence = models.IntegerField(verbose_name='排序')
        status = models.BooleanField(default=True, verbose_name='是否展示')
    
        class Meta:
            db_table = 'tb_content'
    
        def __str__(self):
            return self.category.name + ': ' + self.title

## 二：首页商品模型类 ##

1：创建goods子应用：  
2：模型类：

from django.db import models
    
    
    
    # Create your models here.
    from shopping_mall.utils.models import BaseModel
    
    
    class GoodsCategory(BaseModel):
        """商品类别"""
        name = models.CharField(max_length=10, verbose_name='名称')
        parent = models.ForeignKey('self', related_name='subs', null=True, blank=True, on_delete=models.CASCADE, verbose_name='父类别')
    
        class Meta:
            db_table = 'tb_goods_category'
    
        def __str__(self):
            return self.name
    
    
    class GoodsChannelGroup(BaseModel):
        """商品频道组"""
        name = models.CharField(max_length=20, verbose_name='频道组名')
    
        class Meta:
            db_table = 'tb_channel_group'
    
        def __str__(self):
            return self.name
    
    
    class GoodsChannel(BaseModel):
        """商品频道"""
        group = models.ForeignKey(GoodsChannelGroup, on_delete=models.CASCADE, verbose_name='频道组名')
        category = models.ForeignKey(GoodsCategory, on_delete=models.CASCADE, verbose_name='顶级商品类别')
        url = models.CharField(max_length=50, verbose_name='频道页面链接')
        sequence = models.IntegerField(verbose_name='组内顺序')
    
        class Meta:
            db_table = 'tb_goods_channel'
    
        def __str__(self):
            return self.category.name
    
    
    class Brand(BaseModel):
        """品牌"""
        name = models.CharField(max_length=20, verbose_name='名称')
        logo = models.ImageField(verbose_name='Logo图片')
        first_letter = models.CharField(max_length=1, verbose_name='品牌首字母')
    
        class Meta:
            db_table = 'tb_brand'
    
        def __str__(self):
            return self.name
    
    
    class SPU(BaseModel):
        """商品SPU"""
        name = models.CharField(max_length=50, verbose_name='名称')
        brand = models.ForeignKey(Brand, on_delete=models.PROTECT, verbose_name='品牌')
        category1 = models.ForeignKey(GoodsCategory, on_delete=models.PROTECT, related_name='cat1_spu', verbose_name='一级类别')
        category2 = models.ForeignKey(GoodsCategory, on_delete=models.PROTECT, related_name='cat2_spu', verbose_name='二级类别')
        category3 = models.ForeignKey(GoodsCategory, on_delete=models.PROTECT, related_name='cat3_spu', verbose_name='三级类别')
        sales = models.IntegerField(default=0, verbose_name='销量')
        comments = models.IntegerField(default=0, verbose_name='评价数')
        desc_detail = models.TextField(default='', verbose_name='详细介绍')
        desc_pack = models.TextField(default='', verbose_name='包装信息')
        desc_service = models.TextField(default='', verbose_name='售后服务')
    
        class Meta:
            db_table = 'tb_spu'
    
        def __str__(self):
            return self.name
    
    
    class SKU(BaseModel):
        """商品SKU"""
        name = models.CharField(max_length=50, verbose_name='名称')
        caption = models.CharField(max_length=100, verbose_name='副标题')
        spu = models.ForeignKey(SPU, on_delete=models.CASCADE, verbose_name='商品')
        category = models.ForeignKey(GoodsCategory, on_delete=models.PROTECT, verbose_name='从属类别')
        price = models.DecimalField(max_digits=10, decimal_places=2, verbose_name='单价')
        cost_price = models.DecimalField(max_digits=10, decimal_places=2, verbose_name='进价')
        market_price = models.DecimalField(max_digits=10, decimal_places=2, verbose_name='市场价')
        stock = models.IntegerField(default=0, verbose_name='库存')
        sales = models.IntegerField(default=0, verbose_name='销量')
        comments = models.IntegerField(default=0, verbose_name='评价数')
        is_launched = models.BooleanField(default=True, verbose_name='是否上架销售')
        default_image = models.ImageField(max_length=200, default='', null=True, blank=True, verbose_name='默认图片')
    
        class Meta:
            db_table = 'tb_sku'
    
        def __str__(self):
            return '%s: %s' % (self.id, self.name)
    
    
    class SKUImage(BaseModel):
        """SKU图片"""
        sku = models.ForeignKey(SKU, on_delete=models.CASCADE, verbose_name='sku')
        image = models.ImageField(verbose_name='图片')
    
        class Meta:
            db_table = 'tb_sku_image'
    
        def __str__(self):
            return '%s %s' % (self.sku.name, self.id)
    
    
    class SPUSpecification(BaseModel):
        """商品SPU规格"""
        spu = models.ForeignKey(SPU, on_delete=models.CASCADE, related_name='specs', verbose_name='商品SPU')
        name = models.CharField(max_length=20, verbose_name='规格名称')
    
        class Meta:
            db_table = 'tb_spu_specification'
    
        def __str__(self):
            return '%s: %s' % (self.spu.name, self.name)
    
    
    class SpecificationOption(BaseModel):
        """规格选项"""
        spec = models.ForeignKey(SPUSpecification, related_name='options', on_delete=models.CASCADE, verbose_name='规格')
        value = models.CharField(max_length=20, verbose_name='选项值')
    
        class Meta:
            db_table = 'tb_specification_option'
    
        def __str__(self):
            return '%s - %s' % (self.spec, self.value)
    
    
    class SKUSpecification(BaseModel):
        """SKU具体规格"""
        sku = models.ForeignKey(SKU, related_name='specs', on_delete=models.CASCADE, verbose_name='sku')
        spec = models.ForeignKey(SPUSpecification, on_delete=models.PROTECT, verbose_name='规格名称')
        option = models.ForeignKey(SpecificationOption, on_delete=models.PROTECT, verbose_name='规格值')
    
        class Meta:
            db_table = 'tb_sku_specification'
    
        def __str__(self):
            return '%s: %s - %s' % (self.sku, self.spec.name, self.option.value)

4：恢复数据：

mysql -uroot -pmysql -D shopping_mall -h 192.168.203.153 < goods.sql

## 三：展示首页商品分类： ##

页面静态化测试：  
1：删除主页：  
2：了解前端模板代码：

<ul class="sub_menu">
                {
        % for group in categories.values %}
                <li>
                    <div class="level1">
                        {
        % for channel in group.channels %}
                        <a href="{
        { channel.url }}">{
        {
         channel.name }}</a>
                        {
        % endfor %}
                    </div>
                    <div class="level2">
                        {
        % for cat2 in group.sub_cats %}
                        <div class="list_group">
                            <div class="group_name fl">{
        {
        cat2.name}} ></div>
                            <div class="group_detail fl">
                                {
        % for cat3 in cat2.sub_cats %}
                                <a href="/list.html?cat={
        {cat3.id}}">{
        {
        cat3.name}}</a>
                                {
        % endfor %}
                            </div>
                        </div>
                        {
        % endfor %}
                    </div>
                </li>
                {
        % endfor %}
            </ul>

2: apps/content/crons里面的内容：

from django.template import loader
    from apps.goods.models import GoodsChannel, GoodsCategory
    
    
    def get_categories():
        # 模版参数categories是首页分类频道
        categories = {
        }
    
        # 获取首页所有的分类频道数据
        channels = GoodsChannel.objects.order_by(
            'group_id',
            'sequence'
        )
        # 遍历所有是分类频道，构建以组号作为key的键值对
        for channel in channels:
            # channel: GoodsChannel对象
            if channel.group_id not in categories:
                categories[channel.group_id] = {
        
                    'channels': [],  # 当前分组中的分类频道(一级分类)
                    'sub_cats': []  # 二级分类
                }
            # (1)、填充当前组中的一级分类
            cat1 = channel.category
            categories[channel.group_id]['channels'].append({
        
                'id': cat1.id,
                'name': cat1.name,
                'url': channel.url
            })
    
            # (2)、填充当前组中的二级分类
            cat2s = GoodsCategory.objects.filter(parent=cat1)
            for cat2 in cat2s:
                # cat2：二级分类对象
    
                cat3_list = []  # 每一次遍历到一个二级分类对象的时候，初始化一个空列表，用来构建三级分类
                cat3s = GoodsCategory.objects.filter(parent=cat2)
                # (3)、填充当前组中的三级分类
                for cat3 in cat3s:
                    # cat3；三级分类对象
                    cat3_list.append({
        
                        'id': cat3.id,
                        'name': cat3.name
                    })
    
                categories[channel.group_id]['sub_cats'].append({
        
                    'id': cat2.id,
                    'name': cat2.name,
                    'sub_cats': cat3_list  # 三级分类
                })
    
        return categories
    
    
    def generate_static_index_html():
    
        # 获取分类频道
        categories = get_categories()
    
        # 1:构建首页模板文件对象
        template = loader.get_template("index.html")
    
        # 2:构造动态数据
        content = {
        
            "categories": categories,
            "contents": None,
        }
    
        # 3:渲染完整的页面数据
        page = template.render(content)
    
        # 4:写入静态web服务器
        with open("/home/python/Desktop/shopping-mall-project/front_end_pc/index.html","w") as f:
            f.write(page)

3：生成静态文件：

python3 manage.py shell
    from apps.contets.cores import *
    generate_static_index_html()

4：测试，生成静态文件：  
![在这里插入图片描述][watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L3FxXzQxMzQxNzU3_size_16_color_FFFFFF_t_70_pic_center 4]

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[watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L3FxXzQxMzQxNzU3_size_16_color_FFFFFF_t_70_pic_center 1]: /images/20221123/e5667ce879f4439090e2da1c0bb09eb6.png
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