MTV
We may have heard about the MVC pattern. MVC is the model (model) - view (view) - Abbreviation controller (Controller), and a software design model, with a service logic, data, isolated tissue interface display method code. Django also has its design patterns, which we call MTV.
- M represents a model (Model), i.e., the data access layer. This layer handles all transactions related to the data
- T represents the template (Template), ie, the presentation layer. Such as HTML
- V represents a view (View), i.e., the business logic layer. We write local business code.
Django model
When running our first project and did not involve the operation of the database, if we want to create a table, then how does it work? We can operate in the article / models.py below. Some students might say, models.py not a python file? Have anything to do with the database, because of the special nature of Django, so we can use the object-relational mapping (ORM, Object Relational Mapping), simply means that the form of the operation database operations, then how does it work? We still use the blog taken as an example, assume that blog have a table with title, author, article content, Published composed, then how do we generate a data table in Django below it? We opened article / models.py file, enter the following code:
from django.db import models
# Create your models here.
class Article(models.Model):
title = models.CharField(max_length=10, ) # 标题
author = models.CharField(max_length=10) # 作者
content = models.CharField(max_length=500) # 内容Article we create a class that inherits models.Model, defined four fields: title, author, content date_publish, CharField, DateTimeField is the type of the field, in addition to these two, Django and many other data types in the following table:
| Types of | description |
|---|---|
| Auto Field | For storing digital type integer. |
| BooleanField | Boolean type for storing data (Ture or False) |
| CharField | For storing character data, it is necessary to specify the length max_length. |
| CommaSeparatedIntegerField | A comma-separated integer type data is stored. |
| DateField | Date type, must be "YYYY-MM-DD" format |
| DateTimeField | Date and time type, must be "YYYY-MM-DD HH: MM [: ss [.uuuuuu]] [TZ]" format. |
| DecimalField | Decimal type for storing a decimal number. |
| EmailField | E-mail type |
| FilePathField | Class file path type, FilePathFields must have either 'allow_files' or' allow_folders set to True. |
| FloatField | Float. For storing floating point data. |
| IntegerField | For storing digital type integer. |
| BigIntegerField | Used to store large integer types of digital, the maximum number of support: 9223372036854775807 |
| GenericIPAddressField | Storing the IP address type, IPv4, and the IPv6 address, the format string. |
| NullBooleanField | vlaue must be either None, True or False. |
| PositiveIntegerField | Positive integer |
| PositiveSmallIntegerField | Positive small integer |
| SlugField | Max_length need to define value. |
| SmallIntegerField | Small integer |
| TextField | For storing text data type. |
| TimeField | Time type. "HH: MM [: ss [.uuuuuu]]" format |
| URLField | Used to store the URL address |
| BinaryField | Raw binary data |
But now the article is just a class, not a table, so we have to execute the following two commands, perform a database migration
F:\新建文件夹\blog>python manage.py makemigrations article
Migrations for 'article':
article\migrations\0001_initial.py
- Create model Article
F:\新建文件夹\blog>python manage.py migrate
Operations to perform:
Apply all migrations: admin, article, auth, contenttypes, sessions
Running migrations:
No migrations to apply.python manage.py makemigrations articleEquivalent to establish migrations directory in this app, and all your changes on modes.py of record, such as 0001_initial.py, but this change is not applied to the database file
python manage.py migratethe changes applied to the database file, such as generating table like .