Django's Model class

1、model

And for data exchange (read and incoming data)

 2, snake

Object Relational Mapping Object-relational mapping, python objects in the model and database tables to do mapping

3, Key Concepts

3.1, Class - table corresponding to

A class model corresponding one table in the database. Implementation: Inheritance Model classes (django.db.models.Model)

3.2 Properties - field

Category corresponding to the attribute fields in the database

3.2.1 Types

CharField character type

IntegerField numeric type, the choise enumerated type, packet ancestral ancestral

= models.IntegerField type (choices = ((. 1, ' mechanism ' ), (2, ' program ' ), (3, ' Lecturer ' )), the verbose_name = " category " )

BooleanField Boolean

NullBooleanField can be empty Boolean

AutoField int auto increment, must fill in the parameters primary_key = True, auto_create, automatically created, mysql's auto_increment

FloatField float

DecimalField with Python Decimal types of parameters: max_digits maximum total number of digits after the decimal point decimal_places

TextField text type

UUIDField string type, Django Admin ModelForm and provides verification of the UUID format

# Model class 
class the Order (models.Model): 
    NO = models.UUIDField (= the verbose_name ' Order Number ' ) 
    . Price = models.DecimalField (= the verbose_name ' order amount ' , max_digits =. 6, decimal_places = 2 ) 
    pay_state = models.BooleanField (default = False) 

# create Object 
Import uuid 
Order.objects.create (NO = uuid.uuid4 (),. price = 1819.567, pay_state = True)    # . price only two decimal places, it will be automatically rounded up

FileField file, string, the path will be saved to the database, upload files to a specified directory

　　Parameters: upload_to = "save path" to upload files, storage = None storage component, the default django.core.files.storage.FileSystemStorage

ImageField image, save the path to the database, upload files to a specified directory

　　Parameters: upload_to = "save path" upload file

　　　　   storage = None storage component, the default django.core.files.storage.FileSystemStorage

　　　　　width_field = None, database field names stored in highly upload pictures (string)

　　　　　height_field = None upload pictures stored in the database field name width (string)

DateField date type, format: format: YYYY-MM-DD

　　Parameters: When auto_now each save, the current field is automatically set to the current time, last modification for

　　　　   auto_now_add every save is automatically set to the current time, for the "Created"

　　Note: auto_now and auto_now_add and can only set a default, can not be combined

DateTimeField datetime type datetime.datetime, date + time format YYYY-MM-DD HH: MM [: ss [.uuuuuu]] [TZ]

TimeField time type, format: HH: MM [: ss [.uuuuuu]]

3.2.2 Constraints

The maximum length of max_length

default defaults

The only unique values

primary_key primary key

null  

blank is allowed to enter the air, i.e., an empty string input

db_index Index

db_column specified field name

verbose_name display field names in admin

choices objects comprising a plurality tuple may be iterative, to field provides options for

3.2.3 Relationship

ForeignKey-to-many, many-fold in the field definitions, automatically adds a foreign key in a multiport, such as: store = ForeginKey (Store, db_column = "foreign key column name"), foreign key field: store_id

OneToOneField one, the field definitions at either end

ManyToManyField-many, at both ends of the field definitions

4, meta information

Meta definition of the relevant information to declare a table in a subclass of Model

# Needs to be defined within the class of 
class Meta -: 
    app_label = ''    # Appl Name 
    named db_table, = ''     # table 
    Ordering = []    # sorting field, the first field name may be used '-' indicates reverse 
    the verbose_name = ''    # ADMIN displayed in name 
    unique_together = ''   # Unique combination of fields to set

5、CRUD

5.1, by

5.1.1, Model class object by inserting the recording manager

Syntax: class name Model .objects.create (class attribute = value) in this manner is a direct operation of the database

stu1 = Student.objects.create(name='Negan',sex='m',score=95.0)

5.1.2, insert data model object instantiated

car = Car(name="宝马3",price=20.5)
car.save()

car = Car()
car.name="宝马5i"
car.price=50.5
car.save()

Inserting from the object model is executed in memory, that are operating in memory before not save (), and the database does not matter, only after save (), it will load the data into the database

5.2, search

5.2.1 Filter

qualifying the selected data filter, it may include a plurality of fields, with the "" represents a spaced relationship with

Student.objects.filter = S1 (Sex = ' m ' , name = ' Neagn ' ) 

# support chained calls 
S1 = Student.objects.filter (Sex = ' m ' ) .filter (name = ' Negan ' )

exclude qualified removed

Student.objects.filter = S1 (Sex = ' m ' ) .exclude (socre = 72)   # identify gender m and not score 72

5.2.2 Conditions

Syntax: attribute name = __ operator threshold

gt greater than  

Car.objects.filter(price__gt=30)

lt is less than

greater than or equal gte

less lte

Find exactly what exact, case sensitive

iexact i representatives ignore (ignore) that ignore case

contains contains content, the equivalent of fuzzy query

Car.objects.filter(name__contains='奔')

startswith to begin with ...

Endswith at the end ..

istartswith begin with ..., ignoring case

endswith ending .., ignoring case

icontains contains xx characters, ignoring case

in value terms contained 

Car.objects.filter(price__in=(30.58,26.65))

isnull is null

isnotnull non-null

5.2.3, get the object