The most important part of a model and the only required part of a model is the list of database fields it defines. Fields are specified by class attributes. Be careful not to choose field names that conflict with the models API like clean, save, or delete.
from django.db import models class Musician(models.Model): first_name = models.CharField(max_length=200) last_name = models.CharField(max_length=200) instrument = models.CharField(max_length=200) class Album(models.Model): artist = models.ForeignKey(Musician, on_delete=models.CASCADE) name = models.CharField(max_length=100) release_date = models.DateField() num_stars = models.IntegerField()
Setting a field for storing any type of data is like deciding a data type in C/C++ for storing a particular integer, char etc. Fields in Django are the data types to store a particular type of data. For example, to store an integer, IntegerField would be used. These fields have in-built validation for a particular data type, that is you can not store “abc” in an IntegerField. Similarly, for other fields. This post revolves about major fields one can use in Django Models.
Here are some key attributes one should be aware of before starting to use Django Fields.
Each field in the model should be an instance of the appropriate Field class. Django uses field class types to determine a few things:
- The column type, which tells the database what kind of data to store (e.g. INTEGER, VARCHAR, TEXT).
- The default HTML widget to use when rendering a form field (e.g. <input type=”text”>, <select>).
- The minimal validation requirements, used in Django’s admin and in automatically-generated forms.
Django ships with dozens of built-in field types which can be used to save any type of data from number to entire HTML file too. Here is a list of all Field types used in Django.
Basic model data types and fields list
|AutoField||It An IntegerField that automatically increments.|
|BigAutoField||It is a 64-bit integer, much like an AutoField except that it is guaranteed to fit numbers from 1 to 9223372036854775807.|
|BigIntegerField||It is a 64-bit integer, much like an IntegerField except that it is guaranteed to fit numbers from -9223372036854775808 to 9223372036854775807.|
|BinaryField||A field to store raw binary data.|
|BooleanField||A true/false field.
The default form widget for this field is a CheckboxInput.
|CharField||It is a date, represented in Python by a datetime.date instance.|
|DateField||A date, represented in Python by a datetime.date instance|
|It is used for date and time, represented in Python by a datetime.datetime instance.|
|DecimalField||It is a fixed-precision decimal number, represented in Python by a Decimal instance.|
|DurationField||A field for storing periods of time.|
|EmailField||It is a CharField that checks that the value is a valid email address.|
|FileField||It is a file-upload field.|
|FloatField||It is a floating-point number represented in Python by a float instance.|
|ImageField||It inherits all attributes and methods from FileField, but also validates that the uploaded object is a valid image.|
|IntegerField||It is an integer field. Values from -2147483648 to 2147483647 are safe in all databases supported by Django.|
|GenericIPAddressField||An IPv4 or IPv6 address, in string format (e.g. 192.0.2.30 or 2a02:42fe::4).|
|NullBooleanField||Like a BooleanField, but allows NULL as one of the options.|
|PositiveIntegerField||Like an IntegerField, but must be either positive or zero (0).|
|PositiveSmallIntegerField||Like a PositiveIntegerField, but only allows values under a certain (database-dependent) point.|
|SlugField||Slug is a newspaper term. A slug is a short label for something, containing only letters, numbers, underscores or hyphens. They’re generally used in URLs.|
|SmallIntegerField||It is like an IntegerField, but only allows values under a certain (database-dependent) point.|
|TextField||A large text field. The default form widget for this field is a Textarea.|
|TimeField||A time, represented in Python by a datetime.time instance.|
|URLField||A CharField for a URL, validated by URLValidator.|
|UUIDField||A field for storing universally unique identifiers. Uses Python’s UUID class. When used on PostgreSQL, this stores in a uuid datatype, otherwise in a char(32).|
Django also defines a set of fields that represent relations.
|ForeignKey||A many-to-one relationship. Requires two positional arguments: the class to which the model is related and the on_delete option.|
|ManyToManyField||A many-to-many relationship. Requires a positional argument: the class to which the model is related, which works exactly the same as it does for ForeignKey, including recursive and lazy relationships.|
|OneToOneField||A one-to-one relationship. Conceptually, this is similar to a ForeignKey with unique=True, but the “reverse” side of the relation will directly return a single object.|
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