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Data Model (DM) reference#

This section describes the core Data Model (DM) layer in RESTAlchemy.

The DM layer is responsible for:

  • Declaring domain models as Python classes.
  • Defining fields, types and validation rules.
  • Expressing relationships between models.
  • Providing helper mixins for common patterns (UUID IDs, timestamps, names, etc.).

The DM layer is implemented in the following modules:

  • restalchemy.dm.models
  • restalchemy.dm.properties
  • restalchemy.dm.relationships
  • restalchemy.dm.types
  • restalchemy.dm.filters
  • restalchemy.dm.types_dynamic (advanced types)
  • restalchemy.dm.types_network (network-related types)

This reference focuses on the first five modules, which you will use most of the time.

Quick overview#

A typical DM model is defined like this:

from restalchemy.dm import models, properties, types


class Foo(models.ModelWithUUID):
    # Integer field, required
    value = properties.property(types.Integer(), required=True)

    # Optional string with default value
    description = properties.property(types.String(max_length=255), default="")

Key ideas:

  • You inherit from Model or one of the helper base classes such as ModelWithUUID.
  • You use properties.property() to declare fields.
  • You use types.* classes to describe the type and constraints of each field.

Relationships between models are declared via relationships.relationship().

Filters (restalchemy.dm.filters) are used to describe query conditions when working with storage and API filtering.

Files in this section#

  • Models
  • Model, ModelWithID, ModelWithUUID, ModelWithTimestamp, and other mixins.
  • Properties
  • Property system: Property, IDProperty, PropertyCollection, PropertyManager, helper factories.
  • Relationships
  • relationship(), required_relationship(), readonly_relationship(), Relationship, PrefetchRelationship.
  • Types
  • Scalar, datetime, collection and structured types used in properties.
  • Filters
  • Filter clauses (EQ, GT, In, etc.) and logical expressions (AND, OR).

All of these files exist in four languages with the same structure:

You can find the DM reference in each language under the corresponding reference/dm/ section.