Anotações dos meus estudos

  Agregação >>> Book.objects.aggregate(average_price=Avg('price')) {'average_price': 34.35} Retorna um dicionário contendo o preço médio de todos os livros no queryset. Anotação >>> q = Book.objects.annotate(num_authors=Count('authors')) >>> q[0].num_authors 2 >>> q[1].num_authors 1 q é o conjunto de livros, mas cada livro foi anotado com o número de autores.

 Material de apoio https://www.digitalocean.com/community/tutorials/how-to-get-started-with-the-requests-library-in-python-pt https://requests.readthedocs.io/pt_BR/latest/user/quickstart.html https://realpython.com/python-requests/ https://pythonhelp.wordpress.com/2013/03/12/acessando-recursos-na-web-com-python/

  Recomendação de boas práticas https://steelkiwi.com/blog/best-practices-working-django-models-python/ Lista de opções YEAR_IN_SCHOOL_CHOICES = ( (u'FR', u'Freshman'), (u'SO', u'Sophomore'), (u'JR', u'Junior'), (u'SR', u'Senior'), (u'GR', u'Graduate'), ) Por exemplo: from django.db import models class Person(models.Model): GENDER_CHOICES = ( (u'M', u'Male'), (u'F', u'Female'), ) name = models.CharField(max_length=60) gender = models.CharField(max_length=2, choices=GENDER_CHOICES) Campos de chave primária automáticos Por padrão, o Django dá a cada model o seguinte campo: id = models.AutoField(primary_key=True) Esta é uma chave primária auto incremental. Nesse exemplo, o nome por extenso é "Person's first name" : first_name = models.CharField("Person's first name", max_length=30) Nesse exemplo, o n...

  File Opening Modes There are modes in which you can open a file in Python. The mode you choose depends on how you plan to use the file, or what kind of data you'll be reading (writing) from (to) the file. This mode is specified when opening a file using the built-in open() method, explained in further detail in the next section. Let's take a look at some of the possible combinations of file modes: w: Opens a file for writing and creates a new file if it doesn't yet exist. In the case that the file does exist, it overwrites it. w+: Opens a file for writing but also for reading and creating it if it doesn't exist. If a file already exists, it overwrites it. r: Opens a file for reading only. rb: Opens a file for reading in Binary format. wb: Opens a file for writing in Binary format. wb+: Opens a file for writing and reading in Binary format. a: Opens a file for appending at the end of the file. +: In general, this character is used along side r , w , or a and means bo...

  Django messages tags messages.debug(request, '%s SQL statements were executed.' % count) messages.info(request, 'Three credits remain in your account.') messages.success(request, 'Profile details updated.') messages.warning(request, 'Your account expires in three days.') messages.error(request, 'Document deleted.') Create a messages template #env > mysite > main > templates > main > includes > (New File) messages.html {% if messages %} <ul class="messages"> {% for message in messages %} <li{% if message.tags %} class="{{ message.tags }}"{% endif %}>{{ message }}</li> {% endfor %} </ul> {% endif %} {% block messages %} <ul class="messages" id="messages-list"> {% if messages %} {% for message in messages %} <li> {% if message.tags %} <div class="alert alert-{...

 Django caching https://testdriven.io/blog/django-caching/ https://realpython.com/caching-in-django-with-redis/ Redis https://www.digitalocean.com/community/tutorials/how-to-install-and-secure-redis-on-ubuntu-20-04-pt << ler material para verificar questões de segurança. https://www.tutorialspoint.com/redis/index.htm