formthat

Formthat is a conceptual framework for declarative form generation and validation used in web and mobile interfaces. It proposes describing user interfaces as schemas that specify fields, labels, data types, validation rules, and layout metadata, rather than constructing forms through imperative UI code. The idea is to separate the concerns of data structure, validation, and presentation, enabling reusable form definitions across projects and platforms.

In formthat, a form schema typically defines a collection of fields with attributes such as name, type, required status, and constraints (for example, minimum length or value bounds). It also supports conditional logic, where fields appear or behave differently based on other field values, and metadata for accessibility and localization. Validation rules can be expressed within the schema and enforced both on the client and, optionally, on the server, helping ensure data integrity before submission.

Architecturally, formthat centers on a core engine that parses the schema, applies validators, and coordinates rendering through adapters that connect to specific UI frameworks (such as React, Vue, or native components). This separation allows the same schema to drive multiple renderers and simplifies updates to form behavior without changing the underlying code that handles data.

Usage typically involves creating a schema that describes the form structure, initializing a form instance from that schema, rendering the form through a chosen adapter, and handling submission with automatic validation feedback. Potential benefits include reduced boilerplate, improved consistency, and easier localization, while challenges can include learning a schema language and managing complex conditional logic.

See also: form design, JSON Schema, UI form libraries, form validation.