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Reverse-engineer models with inspectdb

This article explains how to use Django's inspectdb management command to generate model code from an existing SQL Server database.

Prerequisites

Add mssql to your INSTALLED_APPS in settings.py. This step registers the mssql-django management command override for inspectdb, which adds the --schema flag for inspecting non-default schemas:

INSTALLED_APPS = [
    "django.contrib.admin",
    "django.contrib.auth",
    "django.contrib.contenttypes",
    "django.contrib.sessions",
    "django.contrib.messages",
    "django.contrib.staticfiles",
    "mssql",
    "myapp",
]

Note

The mssql database backend works without this step. Adding "mssql" to INSTALLED_APPS is only required to enable the --schema flag on inspectdb. Without it, inspectdb inspects only the default schema (dbo).

Basic usage

Generate models for all tables in the configured database:

python manage.py inspectdb

Save the output directly to a models file:

python manage.py inspectdb > myapp/models.py

Inspect specific tables

Generate models for specific tables only:

python manage.py inspectdb MyTable AnotherTable

Multi-schema support

The mssql-django backend extends inspectdb to support multiple schemas. Specify a schema with the --schema flag:

python manage.py inspectdb --schema "dbo"

python manage.py inspectdb --schema "sales"

This feature is useful for SQL Server databases that organize tables across multiple schemas.

Work with models from multiple schemas

When your database uses multiple schemas, use db_table in the model's Meta class to qualify the table with its schema name. Generated models from inspectdb might not include schema prefixes, so add them manually:

class Customer(models.Model):
    customer_id = models.AutoField(primary_key=True)
    name = models.CharField(max_length=200)

    class Meta:
        managed = False
        db_table = "[sales].[Customer]"

class Product(models.Model):
    product_id = models.AutoField(primary_key=True)
    name = models.CharField(max_length=100)
    price = models.DecimalField(max_digits=10, decimal_places=2)

    class Meta:
        managed = False
        db_table = "[inventory].[Product]"

Important

Use a bracketed two-part name such as "[schema].[table]". The backend treats db_table as a single identifier, so bracketed names are preserved correctly while double-quoted forms are re-quoted as a literal table name.

Cross-schema foreign keys

Django can follow foreign key relationships across schemas as long as both tables are in the same database and the db_table values are set correctly:

class OrderItem(models.Model):
    order_item_id = models.AutoField(primary_key=True)
    product = models.ForeignKey("Product", on_delete=models.CASCADE)
    quantity = models.IntegerField()

    class Meta:
        managed = False
        db_table = "[sales].[OrderItem]"

Django resolves the ForeignKey through the referenced model's db_table value, so no extra schema configuration is needed on the relationship field.

Review generated models

The inspectdb command generates model code that might need manual adjustments:

  1. Set managed = False: Generated models include managed = False in the Meta class, which means Django doesn't manage the table schema. Remove this line if you want Django to manage migrations for the table.

  2. Add primary keys: If a table doesn't have a primary key that inspectdb can detect, you might need to add one manually.

  3. Fix relationship fields: Foreign key relationships might need adjustment, especially for cross-schema references.

Example of generated output:

class Product(models.Model):
    product_id = models.AutoField(primary_key=True)
    name = models.CharField(max_length=100)
    price = models.DecimalField(max_digits=10, decimal_places=2)
    created_at = models.DateTimeField(blank=True, null=True)

    class Meta:
        managed = False
        db_table = "Product"

Limitations

The inspectdb command has the following limitations when used with SQL Server.

Composite primary key inspection

Tables with composite primary keys might not generate complete model definitions. In Django 5.2 and later, define CompositePrimaryKey manually after running inspectdb, or use a surrogate primary key.

Views

The inspectdb command can inspect views, but the generated models might require manual adjustment of field types and null constraints.

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