Common fields and parameters
1 ORM field
AutoField
int auto increment column, the parameter primary must be filled in_ key=True. If there is no auto increment column in the model, a column named id will be automatically created.
IntegerField
An integer type ranging from - 2147483648 to 2147483647.
CharField
Character type, Max must be provided_ Length parameter, max_length indicates the character length.
DateField
Date field, date format: YYYY-MM-DD, equivalent to datetime in Python Date() instance.
DateTimeField
Date time field, format yyyy-mm-dd HH: mm [: SS [. Uuuuuuuuuuuu]] [TZ], equivalent to datetime in Python Datetime() instance
Common and non common fields
AutoField(Field) - int Auto increment column, parameter must be filled in primary_key=True BigAutoField(AutoField) - bigint Auto increment column, parameter must be filled in primary_key=True Note: when model If there is no self incrementing column in, a column named id Columns of from django.db import models class UserInfo(models.Model): # Automatically create a column named id And is a self increasing integer column username = models.CharField(max_length=32) class Group(models.Model): # Custom Auto increment column nid = models.AutoField(primary_key=True) name = models.CharField(max_length=32) SmallIntegerField(IntegerField): - Small integer -32768 ～ 32767 PositiveSmallIntegerField(PositiveIntegerRelDbTypeMixin, IntegerField) - Positive small integer 0 ～ 32767 IntegerField(Field) - Integer column(Signed) -2147483648 ～ 2147483647 PositiveIntegerField(PositiveIntegerRelDbTypeMixin, IntegerField) - Positive integer 0 ～ 2147483647 BigIntegerField(IntegerField): - Long integer(Signed) -9223372036854775808 ～ 9223372036854775807 BooleanField(Field) - Boolean type NullBooleanField(Field): - Boolean value that can be empty CharField(Field) - Character type - Must provide max_length Parameters, max_length Represents the character length TextField(Field) - Text type EmailField(CharField): - String type, Django Admin as well as ModelForm Authentication mechanism is provided in IPAddressField(Field) - String type, Django Admin as well as ModelForm Provide validation in IPV4 mechanism GenericIPAddressField(Field) - String type, Django Admin as well as ModelForm Provide validation in Ipv4 and Ipv6 - Parameters: protocol，Used to specify Ipv4 or Ipv6， 'both',"ipv4","ipv6" unpack_ipv4， If specified as True，Then enter::ffff:192.0.2.1 When, it can be resolved to 192.0.2.1，To enable this function, you need to protocol="both" URLField(CharField) - String type, Django Admin as well as ModelForm Provide validation in URL SlugField(CharField) - String type, Django Admin as well as ModelForm Provides authentication support for letters, numbers, underscores, and connectors (minus signs) CommaSeparatedIntegerField(CharField) - String type, the format must be a comma separated number UUIDField(Field) - String type, Django Admin as well as ModelForm For UUID Format validation FilePathField(Field) - character string, Django Admin as well as ModelForm Provides the function of reading files under folders - Parameters: path, Folder path match=None, Regular matching recursive=False, Recursive folder below allow_files=True, Allow file allow_folders=False, Allow folder FileField(Field) - String, the path is saved in the database, and the file is uploaded to the specified directory - Parameters: upload_to = "" Save path of uploaded file storage = None Storage components, default django.core.files.storage.FileSystemStorage ImageField(FileField) - String, the path is saved in the database, and the file is uploaded to the specified directory - Parameters: upload_to = "" Save path of uploaded file storage = None Storage components, default django.core.files.storage.FileSystemStorage width_field=None, Highly saved database field name (string) of the uploaded picture height_field=None Width of uploaded picture saved database field name (string) DateTimeField(DateField) - date+Time format YYYY-MM-DD HH:MM[:ss[.uuuuuu]][TZ] DateField(DateTimeCheckMixin, Field) - Date format YYYY-MM-DD TimeField(DateTimeCheckMixin, Field) - Time format HH:MM[:ss[.uuuuuu]] DurationField(Field) - Long integer, time interval, in the database according to bigint Storage, ORM The value obtained in is datetime.timedelta type FloatField(Field) - float DecimalField(Field) - 10 Hexadecimal decimal - Parameters: max_digits，Total decimal length decimal_places，Decimal length BinaryField(Field) - Binary type
2 ORM field parameters
null
Used to indicate that a field can be empty.
unique
If set to unique=True, the field must be unique in this table.
db_index
If db_index=True means that the index is set for this field.
default
Set the default value for this field.
DateField and DateTimeField
auto_now_add
Configure auto_now_add=True, the current time will be added to the database when creating the data record.
auto_now
Configure auto on_ Now = true, this field will be updated every time the data record is updated.
3 Relationship fields
ForeignKey
The foreign key type is used to represent the foreign key association relationship in ORM. Generally, the ForeignKey field is set on the "many" side of "one to many".
ForeignKey can be associated with other tables and itself.
to
Sets the table to associate
to_field
Set the fields of the table to associate
related_name
The field name used in reverse operation is used to replace the 'table name' in the original reverse query_ set'.
The following is an example
null Can fields in the database be empty db_column Column names of fields in the database db_tablespace default Default values for fields in the database primary_key Is the field in the database a primary key db_index Can fields in the database be indexed unique Can fields in the database be uniquely indexed unique_for_date Can a unique index be created for the [date] field in the database unique_for_month Can a unique index be created for the [month] field in the database unique_for_year Can a unique index be created for the [year] field in the database verbose_name Admin Field names displayed in blank Admin Allow user input to be blank in editable Admin Can I edit in help_text Admin Prompt for this field in choices Admin The contents of the selection box are displayed in, and the unchanged data is placed in memory, so as to avoid cross table operation For example: gf = models.IntegerField(choices=[(0, 'He Sui'),(1, 'Cousin '),],default=1) error_messages Customize the error information (Dictionary type), so as to customize the error information to be displayed; Dictionary key: null, blank, invalid, invalid_choice, unique, and unique_for_date For example:{'null': "Cannot be empty.", 'invalid': 'Format error'} validators Customize error validation (list type) to customize the desired validation rules from django.core.validators import RegexValidator from django.core.validators import EmailValidator,URLValidator,DecimalValidator,\ MaxLengthValidator,MinLengthValidator,MaxValueValidator,MinValueValidator For example: test = models.CharField( max_length=32, error_messages={ 'c1': 'Priority error message 1', 'c2': 'Priority error message 2', 'c3': 'Priority error message 3', }, validators=[ RegexValidator(regex='root_\d+', message='Wrong', code='c1'), RegexValidator(regex='root_112233\d+', message='Wrong again', code='c2'), EmailValidator(message='Wrong again', code='c3'), ] )
3 Relationship fields
ForeignKey
The foreign key type is used to represent the foreign key association relationship in ORM. Generally, the ForeignKey field is set on the "many" side of "one to many".
ForeignKey can be associated with other tables and itself.
to
Sets the table to associate
to_field
Set the fields of the table to associate
related_name
The field name used in reverse operation is used to replace the 'table name' in the original reverse query_ set'.
related_query_name
The join prefix used in the reverse query operation, which is used to replace the table name.
on_delete
When data in an associated table is deleted, the behavior of the current table and its associated rows.
models.CASCADE
Delete the associated data and delete the associated data
models.DO_NOTHING
Deleting associated data raises an error integrity error
models.PROTECT
Deleting associated data raises the error ProtectedError
models.SET_NULL
Delete the associated data and set the associated value to null (provided that the FK field needs to be set to nullable)
models.SET_DEFAULT
Delete the associated data and set the associated value as the default value (provided that the FK field needs to be set as the default value)
models.SET
Delete associated data,
a. set the associated value to the specified value, setting: models Set (value)
db_constraint
Whether to create a foreign key constraint in the database. The default is True.
OneToOneField
One to one field.
Usually, one-to-one fields are used to extend existing fields.
The one-to-one association relationship is often used when the query frequency difference between different fields in a table is too large. The fields that could have been stored in one table are disassembled and placed in two tables, and then the two tables establish a one-to-one association relationship.
to
Set the table to associate.
to_field
Set the fields to associate.
on_delete
Same as ForeignKey field.
ManyToManyField
Used to represent many to many relationships. In the database, the association relationship is established through the third table
to
Sets the table to associate
related_name
Same as ForeignKey field.
related_query_name
Same as ForeignKey field.
symmetrical
It is only used to specify whether to create a reverse operation internally when many to many Auto Association. The default is True.
through
When using the ManyToManyField field, Django will automatically generate a table to manage many to many relationships.
However, we can also manually create the third table to manage the many to many relationship. At this time, we need to specify the table name of the third table through through.
through_fields
Set the associated field.
db_table
The name of the table in the database when the third table is created by default.