django | 易学教程

How to properly serve my Angular application static files from a Django project on Heroku?

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Pass context from one serializer to another?

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问题 With Django REST Framework, I have 2 serializers: PageSerializer and CommentSerializer . CommentSerializer depends on some extra "context" value, but it doesn't get it directly, instead it needs to get it from PageSerializer , since they have a nested relationship. So I need to have something like this: class CommentSerializer(serializers.ModelSerializer): ... my_field = serializers.SerializerMethodField() def get_my_field(self, comment): my_value = self.context['my_value'] ... class

Django Query to Aggregate the Sum for Matching Instances in the Same Field

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问题 I have the following Django (2.1) model: class Sales(models.Model): product_name = models.ForeignKey(Product) category = models.ForeignKey(Category) sales= models.DecimalField(max_digits=25) I would like to receive the sum of all sales for each different product_name instance that is the same. For example, I have the following sales by product_name : DVDs = 6.00 DVDs = 6.00 Books = 14.00 Books = 6.00 Magazines = 4.00 Magazines = 4.00 I can use Sales.objects.aggregate(sales=Sum('sales')) to

How to retrieve image files from mongodb to html page

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问题 I have successfully stored image files in mongdb in binary format.but when i m getting image from mongodb i m getting the same banary format.But i need this image file.Please someone could help This is the code i used def retrieve(request): db=pymongo.connection.Connection('localhost',27017).demo1 grid=gridfs.GridFS(db) output=grid.get_last_version(filename='shiva.jpg') return HttpResponse(output) 回答1: Hi i have successfully inserted and retrieved image from mongodb with python.. def insert

django:redis:CommandError: You have not set ASGI_APPLICATION, which is needed to run the server

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问题 I am trying to create socket in django. I installed asgi_redis as per this link. When I ran the command python manage.py runserver, I am getting below error. >python manage.py runserver CommandError: You have not set ASGI_APPLICATION, which is needed to run the server. As I havent started the redis, above error might be because of this. I am bit confused , do I need to install Redis separately or just need to start the redis as I have already installed the asgi_redis? project/settings.py file

Show the dictionary key in django template

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问题 Im wondering how i could show the dictionary key itself in a django template Example dictionary: resources = {'coin': coin, 'grain': grain, 'iron': iron, 'stone': stone, 'wood': wood,} Template <b>Coin: </b>{{ upgrade.coin }} Were i want to use the dictionary key (+some html) instead of the hard coded "Coin:" Can anyone please help me out? 回答1: Use for tag with dict.items if you want to print all key/value pairs: {% for key, value in resources.items %} <b>{{ key }}: </b>{{ value }} {% endfor

Django: Why is Foo.objects.extra(…) So Much Faster Than Foo.objects.raw?

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问题 So I am trying to optimize a fairly odd query, but this is a legacy database so I make do with what I have. These are the queries I am trying. They provide the same output at this point. w is my queryset. def future_schedule(request): past = datetime.date.today()-datetime.timedelta(days=730) extra_select = { 'addlcomplete': 'SELECT Complete FROM tblAdditionalDates WHERE Checkin.ShortSampleID = tblAdditionalDates.ShortSampleID', 'addldate': 'SELECT AddlDate FROM tblAdditionalDates WHERE

python主流框架简介和Django框架的使用

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[TOC] 一、手撸简易web框架通过统一思想，对各个功能或者接口进行统一，越来越像是Django框架的流程，实现了低配版的Django。下面是具体的流程图具体步骤为：wsgiref库拿到用户的请求内容，我们判断用户请求的链接地址内容，匹配到对应的后端函数，后端函数内部调用数据库得到需要的数据，再拿到html文件进行读取后，之后再把数据通过jinja2模块语法插入html文件中，最后再把修改过后的html文件return出去。wsgiref库把该html文件内容发送回浏览器，浏览器拿到内容后展示在页面上。结束。基于第三方模块帮你撸使用了wsgiref库和jinja2库 wsgiref库帮我们封装了http协议，并将http的请求头和请求首行变成字典。即将请求内容解包，响应的内容压包。 jinja2库专门用来处理后端数据与html页面的交互 views.py 里面的放的是函数我们管这些函数叫视图函数视图层 urls.py 里面放的是路由(后缀)与视图函数的对应关系路由层 templates文件夹里面放的全是html文件模板层二、动静态网页 1. 静态网页数据是写死的万年不变(哪怕改变了也是人为直接修改) 2. 动态网页数据是实时获取的 eg: 1 后端代码动态获取当前时间 2 数据是从数据库查询出来的三、jinja2模板语法 1. jinja2的作用

Django nested URLs

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问题 How do I nest url calls in django? For example, if I have two models defined as class Post(models.Model): title = models.CharField(max_length=50) body = models.TextField() created = models.DateTimeField(auto_now_add=True, editable=False) def __unicode__(self): return self.title @property def comments(self): return self.comment_set.all() class Comment(models.Model): comment = models.TextField() post = models.ForeignKey(Post) created = models.DateTimeField(auto_now_add=True) With the following

Django nested URLs

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