Django's Object-Relational Mapping layer converts Python classes into relational database structures. Defining a model requires subclassing models.Model:

from django.db import models

class Contributor(models.Model):
    full_name = models.CharField(max_length=100)
    contact_email = models.EmailField()
    is_verified = models.BooleanField(default=False)
    registration_date = models.DateTimeField(auto_now_add=True)

Applying migration commands against this definition produces a corresponding schema. In PostgreSQL environments, the resulting command appears as:

CREATE TABLE myapp_contributor (
    id SERIAL PRIMARY KEY,
    full_name VARCHAR(100) NOT NULL,
    contact_email VARCHAR(254) NOT NULL UNIQUE,
    is_verified BOOLEAN DEFAULT FALSE,
    registration_date TIMESTAMP WITHOUT TIME ZONE NOT NULL
);

The framework automatically prefixes the table name using the application label and appends the lowercase model identifier. This naming convention can be customized through the Meta configuration. An auto-incrementing integer primary key named id attaches itself to every class unless explicitly overridden or suppressed. Additionally, Django abstracts vendor-specific syntax, compiling statements that align with the database backend configured in the project settings.

To activate the application containing these definitions, append its dotted module path to the INSTALLED_APPS list:

INSTALLED_APPS = [
    # ... default configurations ...
    'myapp',
]

Core Field Mappings

Each attribute corresponds to a specific database column type via dedicated field classes:

• CharField: Variable-length strings. Requires the max_length parameter.
• TextField: Unlimited text blocks suited for long-form content.
• IntegerField: Standard signed integer storage.
• FloatField: IEEE 754 floating-point numbers.
• DecimalField: Precise decimal arithmetic. Demands max_digits and decimal_places arguments. Example: budget = models.DecimalField(max_digits=6, decimal_places=2) reserves six total positions with two fractional digits.
• DateField: Calendar dates excluding time components.
• DateTimeField: Timestamps with optional timezone support.
• BooleanField: Binary flags mapping to true/false states.
• SlugField: URL-safe strings inheriting character restrictions from CharField.
• ImageField: Secure binary references extending FileField for raster assets.

Constraint Configuration

Field instantiations accept keyword arguments governing validation and persistence behavior:

• primary_key: Marks the attribute as the row identifier. Omission triggers automatic ID provisioning.
• unique: Guarantees distinct values across all records.
• default: Establishes fallback values during initialization. Accepts static literals or callable functions.
• null: Regulates database-level NULL acceptance. Defaults to False to preserve data integrity and indexing efficiency.
• blank: Controls frontend form validation tolerance. Setting to True permits empty submissions independent of the null parameter.
• db_column: Replaces the auto-derived column name with a custom identifier.
• db_index: Generates a dedicated B-tree structure to optimize search operations.
• choices: Restricts inputs to a fixed sequence of tuple pairs representing internal codes and human labels.

Metadata Directives

Customization scales through the nested Meta class:

class WriterProfile(models.Model):
    display_alias = models.CharField(max_length=50)
    membership_start = models.DateTimeField()

    class Meta:
        abstract = True
        db_table = 'author_archives'
        ordering = ['-membership_start', 'display_alias']
        verbose_name = 'Writer Record'
        verbose_name_plural = 'Writer Records'

Key Meta parameters include:

• abstract: Prevents table generation while enabling field inheritance for descendant models.
• app_label: Manually binds unattached models to a specific application namespace.
• db_table: Specifies the exact physical table name, bypassing default naming algorithms.
• ordering: Dictates default query result sorting. Prefix identifiers with hyphens for descending sequences. Multiple criteria apply sequentially from left to right.
• verbose_name / verbose_name_plural: Supplies readable descriptors utilized by administrative panels and automated documentation generators.