modelschema

ModelSchema is a formal specification of data models used in software systems to describe the structure, validation rules, and relationships of domain entities. It serves as an abstraction layer that articulates what data a model contains, how it is validated, and how it maps to storage and transmission formats.

A model schema typically defines fields with types (such as string, integer, date), constraints (required, nullable, min/max length, pattern, uniqueness), default values, and annotations. It also describes relationships between models (one-to-one, one-to-many, many-to-many) and supports metadata such as indexing, read-only flags, and allowed values. Validation logic and cross-field rules may be declared within the schema to ensure data integrity before persistence or serialization.

Model schemas are used to drive multiple concerns. They guide object-relational mappers and document-store mappers, generate database migrations, and power serializers and API schemas for JSON or other formats. They can be expressed in formats such as JSON, YAML, or native programming language constructs, and may be mapped to or from schema languages like JSON Schema, OpenAPI, or GraphQL type definitions.

In practice, model schemas promote consistency across validation, serialization, and persistence layers and support versioning and evolution of data models. They also require maintenance to keep the schema aligned with code, storage, and external interfaces, as drift can lead to runtime errors if the model interpretation diverges across components.